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Hello, readers! I am now posting my Astronomy Skylights on my website. This will allow me to embed larger and “embiggable” photos. They will still be free.
You can find the new blogs, posted every Sunday afternoon, here: http://astrogeo.ca/skylights/
Thanks, and I hope to see you over at AstroGeo!
Hi Chris, I have been following your news. Can I check when you talked about an event happens on certain date, does it make any difference if I live in southern or northern atmosphere? In my case I live in Australia and felt I missed a few events due to time differences. Regards, Jos
Hi, Jos. Thanks for asking! Moon phase and planet events are seen by everyone on Earth, basically at the same time. It’s complicated by the fact that events that happen at a particular moment in time will only be visible by the half of the Earth for whom the moon or that planet is above the horizon, and only by those who have dark skies at that time.
That’s why I’ll say that a Jupiter shadow transit or a great red spot appearance occurs at a specific time in the Eastern Daylight Time (EDT) zone. To see if it’s visible where you live, add or subtract the appropriate number of hours to convert to your time zone. If it converts to a daytime hour, or if Jupiter isn’t above the horizon for you, you’re not seeing that event.
If I say an event happens in local time, everyone sees it (see twists below). Your best bet is to download a good astronomy app, and it’ll show you the event where you are. SkySafari is especially good for Jupiter events, because it displays the rotation of the planet.
There are two final twists to our story. First - the up, down, left, and right directions I mention are flipped when viewed from south of the equator. That’s why I often add the celestial direction, which is independent of one’s location on Earth.
Secondly, the angle that the ecliptic (more or less the plane of the solar system) makes with the horizon varies with your latitude on Earth (but not the longitude). At high latitudes the ecliptic is more parallel to the horizon. At the Earth’s equator, the ecliptic is always close to vertical. That’s why it gets dark fast after sunset in the tropics. At the same time, a slanted ecliptic in northern hemisphere corresponds to a steep ecliptic in the southern hemisphere.
The tilted ecliptic effects how easy it is to see Mercury. If I say Mercury is easy to see after sunset, that may only apply to northerners. I’d have to write a separate description for southerners.
Other celestial sights that vary depending on whether you are north or south of the equator are meteor showers and comets. Once again, an app is helpful there.
Keep looking up! Or down, if you live down under ;)!
Above: On Wednesday, September 4 from 9:21 to 11:33 pm EDT, observers in the Americas can watch Io’s shadow transit Jupiter, accompanied by the Great Red Spot, as shown here for 10 pm EDT)
Hello, Late Summer Stargazers!
Here are your Astronomy Skylights for the week of September 1st, 2019 by Chris Vaughan. Feel free to pass this along to your friends and send me your comments, questions, and suggested topics. I repost these emails with photos at http://astrogeoguy.tumblr.com/ where all the old editions are archived. You can also follow me on Twitter as @astrogeoguy! Unless otherwise noted, all times are Eastern Time. Please click this MailChimp link to subscribe to these emails.
I can bring my Digital Starlab inflatable planetarium to your school or other daytime or evening event. Contact me, and we’ll tour the Universe together!
The Moon and Planets
If last week was the best week for skywatchers worldwide, this is the week for lunatics – the lovers of our natural satellite, Luna! Between now and next Sunday, the moon will March across the evening sky worldwide, waxing in phase and visiting two bright planets. Meanwhile, we have a minor meteor shower underway, and we can enjoy summer constellation sights in evening, autumn ones at midnight, and our winter treats during the pre-dawn hours. Here are your Skylights!
The moon will begin the week as a delicate waxing crescent visible over the western horizon after sunset. Watch for Earthshine - sunlight that has reflected off the seas and white clouds of Earth and is illuminating the unlit portion of the moon’s near side. The bright, white star that you see below the moon (or above it, if you live south of the Equator) on Sunday and Monday evening is Spica, the brightest star in Virgo (the Maiden). Note how the moon moves with respect to that star from one night to the next.
On Wednesday and Thursday, the now healthy crescent moon will pass through the modest stars of Libra (the Scales). The moon never wanders far from the Ecliptic, the imaginary line that traces the sun’s path through the zodiac constellations. So the moon is usually within those familiar constellations, allowing you to see where they are – even after the moon has moved away from them.
Thursday will bring the First Quarter Moon phase - when the angle formed by the sun, Earth, and moon forms a right-angle, causing the moon to appear half-illuminated, on its eastern side. (East and west on the moon are opposite to sky directions on Earth.) First quarter moons always rise around noon time, allowing you to see them in the afternoon. Evenings around first quarter are the best ones for viewing the moon in binoculars and backyard telescopes. The topography along the terminator – the pole-to-pole line that divides the lit and dark halves – is being lit by low-angled sunlight which produces breathtaking vistas of bright mountain peaks and crater rims, and the deep black shadows they cast. Moon phases are shared by everyone around the world.
(Above: On Thursday, observers worldwide will see the First Quarter moon near very bright Jupiter, as shown here at 9:30 pm EDT. The following nights, the moon will hop east of Jupiter and then do the same for Saturn.)
Thursday night will also begin the moon’s dance with the gas giant planets. Look for the moon in the southwestern sky, and positioned less than four finger widths to the right (or 4 degrees to the celestial northwest) of the bright planet Jupiter. The moon and Jupiter will both fit within the field of view of binoculars. If you watch the pair over several hours, starting at dusk, you will see the moon’s orbit carry it closer to the planet. Look for the bright reddish star Antares “the Rival of Mars” twinkling below the moon. That is the heart of Scorpius (the Scorpion). To the west of Antares, three little white stars in a vertical line and each separated by three finger widths from the next one, represent the critter’s claws. Remember that Jupiter will stay with the scorpion after the moon moves away – all autumn, in fact.
On Friday night, the waxing gibbous (i.e., more than half-full) moon will hop to sit on the east side of Jupiter. Then, on Saturday night, the moon will land immediately above the Teapot-shaped stars of Sagittarius (the Archer), and a palm’s width the right (or celestial west) of Saturn. As with Jupiter, the moon will hop to the other side of Saturn on Sunday night – and the ringed planet will stay near the Teapot for the rest of this year.
Mercury, Venus, and Mars are out of sight - hidden in the sun’s glare, for now. But the two fast inner planets will bring them into view in the evening sky next week.
As the sky begins to darken this week, look for the giant planet Jupiter sitting less than a third of the way up the southwestern sky. Hour by hour, Jupiter will sink lower – then set in the west before midnight local time. Jupiter is spending the rest of this year between Ophiuchus (the Serpent-Bearer) and Scorpius (the Scorpion). Normally a planet becomes harder to see when it reaches the southwestern evening sky. But the earlier sunsets and the planet’s brilliance will keep it in view for some time to come.
On a typical night, even a backyard telescope will show you Jupiter’s two main equatorial stripes and its four Galilean moons - Io, Europa, Callisto, and Ganymede looking like small white dots arranged in a rough line flanking the planet. If you see fewer than four dots, then some of them are in front of Jupiter, or hidden behind it. Good binoculars will show the moons, too!
From time to time, the small, round, black shadows cast onto Jupiter’s surface by those four Galilean moons become visible in amateur telescopes as they cross (or transit) Jupiter’s disk. On Wednesday, September 4 from 9:21 to 11:33 pm EDT, observers in the Americas can watch Io’s shadow transit Jupiter, accompanied by the Great Red Spot!
Due to Jupiter’s rapid 10-hour rotation period, the Great Red Spot (or GRS) is only observable from Earth every 2nd or 3rd night, and only during a predictable three-hour window. The GRS will be easiest to see using a medium-sized, or larger, aperture telescope on an evening of good seeing (steady air). If you’d like to see the Great Red Spot in your telescope, it will be crossing the planet on Monday evening from dusk to 11 pm EDT, on Wednesday from 9:20 to 11:30 pm EDT (accompanied by the Great Red Spot), and on Saturday from dusk until 10 pm EDT.
Yellow-tinted Saturn is prominent in the southern evening sky, too - but it is less bright than Jupiter. The ringed planet will be visible from dusk until about 2 am local time. Saturn’s position in the sky is just to the upper left (or celestial east) of the stars that form the teapot-shaped constellation of Sagittarius (the Archer). To find Saturn, look about 3 fist diameters to the left (east) of Jupiter. The Milky Way is between them.
Dust off your telescope! Once the sky is dark, even a small telescope will show Saturn’s rings and several of its brighter moons, especially Titan! Because Saturn’s axis of rotation is tipped about 27° from vertical (a bit more than Earth’s axis), we can see the top surface of its rings, and its moons can arrange themselves above, below, or to either side of the planet. During this week, Titan will migrate counter-clockwise around Saturn, moving from the upper left of Saturn tonight (Sunday) to below the planet next Sunday. (Remember that your telescope will flip the view around.)
Tiny, blue Neptune will rise at dusk this week, and then it will climb the eastern sky until it reaches its highest point, due south, at about 1:30 am local time. The planet is among the stars of Aquarius (the Water-Bearer). Recently, Neptune has been sitting just to the left (celestial east) of a medium-bright star named Phi (φ) Aquarii. Neptune is actually moving slowly toward that star and will “kiss” it on Thursday and Friday nights this week, an event that will help you locate dim Neptune.
Astronomers call such an event a conjunction. Being so close together, both the star and Neptune will appear together in the field of view of a telescope. But blue Neptune’s light has been travelling for 4 hours to reach your eye, while the warmly-tinted light of Phi Aquarii has been journeying for 202 years! After this weekend, the distance between the two objects will increase due to Neptune’s eastward orbital motion.
(Above: The path of blue Neptune past the medium-bright stat Phi Aquarii will produce a close conjunction on September 5 and 6. Each yellow dot represents 6 hours of Neptune’s orbital motion this week. They will make an interesting sight in backyard telescopes.)
Blue-green Uranus will be rising in the east just before 10 pm local time this week; and it will remain visible all night long. Uranus is sitting below (celestial south of) the stars of Aries (the Ram) and is just a palm’s width above the head of Cetus (the Whale). At magnitude 5.8, Uranus is actually bright enough to see in binoculars and small telescopes, under dark skies – and it really does look blue! You can use the three modest stars that form the top of the head of the whale (or sea-monster in some tales) to locate Uranus for months to come – that’s because that distant planet moves so slowly in its orbit. To help you find it, I posted a detailed star chart here.
(Above: The Ice Giant planets are visible in late evening, as shown here at 10:30 pm local time.)
Aurigids Meteor Shower
A minor meteor shower named the Aurigids is underway. It peaks today (Sunday) and ends next weekend. Look for several of these meteors per hour. They’ll be moving away from the northeastern horizon, where the constellation that gives them their name, Auriga (the Charioteer), rises in late evening.
The Northern Crown Rests in the West
Corona Borealis (the Northern Crown) can be spotted halfway up the
western evening sky in early September. The constellation actually sits about
midway along the imaginary line that joins the two bright stars Vega and
Arcturus. The earlier autumn sunsets extend our opportunity to explore Corona
Borealis. This incomplete circlet of medium-bright stars is roughly 7 degrees
across (a generous palm’s width). It is both a constellation and an asterism (an informal star pattern). Corona
Borealis’ brightest star Alphecca is a white,
A-class star located 75 light-years from the sun. Alphecca’s placement in the
constellation is reminiscent of a diamond in a ring. The star’s name derives
from the Arabic expression for “broken”, referring to the incomplete ring.
(Above: The distinctive constellation of Corona Borealis, the Northern Crown, sits in the western evening sky - midway between the two bright stars Vega (at top centre) and Arcturus. The sky is shown for 10 pmlocal time this week.)
While the Northern Crown is poor in deep sky objects, it contains several interesting jewels - double and variable stars. Alphecca itself is an eclipsing binary system that varies in brightness by a tiny amount every 17.36 days, similar to the behavior of the star Algol in Perseus (the Hero). Eruptive variable stars are named for R Coronae Borealis, which is located about three finger widths above (or 3.5 degrees to the celestial northeast of) Alphecca. R Corona Borealis is a hydrogen-deficient and carbon-rich supergiant star. From time to time, it’s usual visual magnitude of 5.8 drops to as little as magnitude 14, possibly due to the formation of opaque carbon dust that blocks visible light, but passes infrared wavelengths. Another star named S Coronae Borealis exhibits the same range of variability, but with a 360-day period. The Blaze Star (T Coronae Borealis) is a cataclysmic variable star, also called a recurrent nova-type. Normally shining between visual magnitude 10.2 and 9.9, on rare occasions it has brightened to magnitude 2 in a period of hours, caused by a nuclear chain reaction and the subsequent explosion.
(Above: The crown’s jewels include the variable stars R, S, and T Coronae Borealis)
August-September Stargazing Suggestions - Lyra
If you missed last week’s tour of the constellation of Lyra (the Harp), I posted it here. Over the next weeks, we’ll look at some other constellations, too.
Public Astro-Themed Events
Taking advantage of the moon and other bright objects in the sky this week, the RASC Toronto Centre astronomers will hold their free monthly public City Sky Star Party in Bayview Village Park (steps from the Bayview subway station), starting around 8 pm on the first clear weeknight this week (Tues to Thu only). You don’t need to be an RASC member, or own any equipment, to join them – looks are free! Check here for details, and check the banner on their website home page or Facebook page for the GO or NO-GO decision around 5 pm each day.
Every Monday evening, York University’s Allan I. Carswell Observatory runs an online star party - broadcasting views from four telescopes/cameras, answering viewer questions, and taking requests! Details are here. On Wednesday nights they offer free public viewing through their rooftop telescopes. If it’s cloudy, the astronomers give tours and presentations. Details are here.
If the skies are clear on Thursday evening, September 5, local astronomers will set up their telescopes in Old Thornhill Village. This free event starts at 8 pm and everyone is welcome to come out for a look at the Moon, Jupiter and Saturn, and a variety of deep-sky treasures. The viewing location is Thornhill’s very own “dark-sky oasis,” the Pomona Meadow - situated north of the cemetery on Charles Lane, and east of the Ukrainian Catholic Church of St. Volodymyr. Park for free at the church and just follow the paved path. The rain or cloud date is Thursday, October 3 at 7:00 pm. Dress warmly, and we’ll see you there!
Eastern GTA sky watchers are invited to join the RASC Toronto Centre and Durham Skies for solar observing and stargazing at the edge of Lake Ontario in Millennium Square in Pickering on Friday evening, September 6, from 6 pm to 11 pm. Details are here. Before heading out, check the RASCTC home page for a Go/No-Go call in case it’s too cloudy to observe. The rain date is Saturday. That same evening, RASC and Durham Skies will be donating a telescope to the Pickering Public Library in a public ceremony. In case of rain or bad weather, the ceremony will be moved to the Pickering Library Auditorium (2nd floor) at 1 The Esplanade.
If it’s sunny on Saturday morning, September 7 from 10 am to noon, astronomers from the RASC Toronto Centre will be setting up outside the main doors of the Ontario Science Centre for Solar Observing. Come and see the Sun in detail through special equipment designed to view it safely. This is a free event (details here), but parking and admission fees inside the Science Centre will still apply. Check the RASC Toronto Centre website or their Facebook page for the Go or No-Go notification.
Please note: Due to some filming permits at DDO, some of our events in September have been cancelled. Here’s the updated information…
The next RASC-hosted Night at the David Dunlap Observatory will be on Saturday, September 21. There will be sky tours in the Skylab planetarium room, space crafts, a tour of the giant 74” telescope, and viewing through the 74” and lawn telescopes (weather permitting). The doors will open at 8:30 pm for a 9 pm start. Attendance is by tickets only, available here. If you are a RASC Toronto Centre member and wish to help us at DDO in the future, please fill out the volunteer form here. And to join RASC Toronto Centre, visit this page.
This Fall and Winter, spend a Sunday afternoon in the other dome at the David Dunlap Observatory! On Sunday afternoon, October 20, from noon to 4 pm, join me in my Starlab Digital Planetarium for an interactive journey through the Universe. We’ll tour the night sky and see close-up views of galaxies, nebulas, and star clusters, view our Solar System’s planets and alien exo-planets, land on the moon, Mars - and the Sun, travel home to Earth from the edge of the Universe, hear indigenous starlore, and watch immersive fulldome movies! Ask me your burning questions, and see the answers in a planetarium setting - or sit back and soak it all in. Sessions run continuously between noon and 4 pm. Ticket-holders may arrive any time during the program. The program is suitable for ages 3 and older, and the Starlab planetarium is wheelchair accessible. For tickets, please use this link.
Keep looking up, and enjoy the sky when you do. I love questions and requests - so, send me some!
(Above: On Monday, September 2 from 5:00 to 5:03 am EDT, the International Space Station will glide over the GTA in a bright pass, exiting Earth’s shadow over the west-northwestern horizon and then setting in the northeast.)
The ISS (International Space Station) is visible silently gliding over the GTA this week. The best passes at (mostly) convenient times are listed below. (Note: The more negative the Mag. number, the brighter. The larger the Alt. number, the higher up it is!) Some passes are high and bright! (Data adapted from www.Heavens-above.com. If you enter your location in their website, you will get a list of passes for your location.) All the times are in Eastern Time.
Date Start & End Times (EDT) Direction of Travel Max Alt. Mag.
Mon, 2-Sep 4:59:49 am to 5:03:41 am moves WNW to NE 47° -3.2 !!
Tue, 3-Sep 4:12:59 am to 4:14:58 am moves NE to NE 32° -2.0
Tue, 3-Sep 5:45:59 am to 5:51:33 am moves WNW to NE 24° -1.9
Wed, 4-Sep 4:59:00 am to 5:02:46 am moves NW to NE 28° -2.3
Thu, 5-Sep 4:12:07 am to 4:14:02 am moves NNE to NE 26° -1.7
Thu, 5-Sep 5:45:40 am to 5:50:54 am moves NW to NE 21° -1.6
Fri, 6-Sep 4:58:07 am to 5:01:57 am moves NW to NE 22° -1.7
Sat, 7-Sep 4:11:14 am to 4:13:05 am moves NNE to NE 21° -1.3
Sat, 7-Sep 5:45:01 am to 5:50:29 am moves NW to ENE 22° -1.6
Sun, 8-Sep 4:57:15 am to 5:01:21 am moves NNW to NE 21° -1.5
There are no visible Iridium Flares predicted for the GTA this week.
Keep looking up, and enjoy the sky when you do. I love questions and requests - so, send me some!
Hi, I live in downtown Toronto and at 6:17 this morning happened to be looking out my south facing bedroom window and saw a big, slow green and yellow/orange ball streak in the dawn sky from west to east. It was unlike any meteor streak I've ever seen (I've watched many showers) and besides, the sky was notably already bright. What was I looking at? Thanks for any insight you can provide, it was really something but has me confused as I'm uneducated on the astronomical world. Thanks!
Hi, and thanks for asking! It depends on what you mean by “slow”. A bolide, or fireball, can take several seconds to cross the sky, and many people simultaneously see the same one - but I didn’t see any reports from this morning, August 31, 2019. It’s more likely you were seeing an aircraft or its exhaust, which can appear in strange ways at dawn and dusk, because the object catches sunlight from below the horizon. Those sightings can linger for minutes. Keep looking up!
(Above: On Wednesday, August 28 from 5:47 to 5:56 am EDT, the International Space Station will glide over the GTA in a very bright pass, exiting Earth’s shadow over the southwestern horizon and then passing above Orion before setting in the east-northeast.)
The ISS (International Space Station) is visible silently gliding over the GTA this week. The best passes at (mostly) convenient times are listed below. (Note: The more negative the Mag. number, the brighter. The larger the Alt. number, the higher up it is!) Some passes are high and bright! (Data adapted from www.Heavens-above.com. If you enter your location in their website, you will get a list of passes for your location.) All the times are in Eastern Time.
Date Start & End Times (EDT) Direction of Travel Max Alt. Mag.
Mon, 26-Aug 5:49:15 am to 5:54:13 am moves S to E 19° -1.5
Wed, 28-Aug 5:47:26 am to 5:53:53 am moves SW to ENE 49° -3.1 !!
Thu, 29-Aug 5:00:48 am to 5:04:53 am moves S to ENE 29° -2.3
Fri, 30-Aug 4:14:05 am to 4:15:36 am moves ESE to E 16° -1.3
Fri, 30-Aug 5:46:58 am to 5:53:02 am moves WSW to NE 67° -3.6 !!
Sat, 31-Aug 5:00:12 am to 5:04:13 am moves SW to ENE 76° -3.8 !!
Sun, 1-Sep 4:13:22 am to 4:15:18 am moves E to ENE 29° -1.9
Sun, 1-Sep 5:46:14 am to 5:51:59 am moves W to NE 34° -2.6 !!
There are no visible Iridium Flares predicted for the GTA this week.
Keep looking up, and enjoy the sky when you do. I love questions and requests - so, send me some!
(Above: This image of the Ring Nebula in Lyra was produced by combining images from the Hubble Space Telescope with infrared data from the ground-based Large Binocular Telescope in Arizona. In the image, the blue color represents helium; the green, oxygen; and the red, hydrogen. hubblesite.org)
Hello, Late Summer Stargazers!
Here are your Astronomy Skylights for the week of August 25th, 2019 by Chris Vaughan. Feel free to pass this along to your friends and send me your comments, questions, and suggested topics. I repost these emails with photos at http://astrogeoguy.tumblr.com/ where all the old editions are archived. You can also follow me on Twitter as @astrogeoguy! Unless otherwise noted, all times are Eastern Time. Please click this MailChimp link to subscribe to these emails.
I can bring my Digital Starlab inflatable planetarium to your school or other daytime or evening event. Contact me, and we’ll tour the Universe together!
The Moon and Planets
This is the favorite week of the lunar month for skywatchers worldwide. The nights between Last Quarter and the New Moon are delightfully dark, and the mild temperatures will entice you outside to see the sights. Here are your Skylights!
The moon will begin the week as a pretty waning crescent that rises in the wee hours among the stars of Gemini (the Twins). That late-rising moon will remain visible during the daylight hours – well into the afternoon, in fact. Low in the east-northeastern sky, just before dawn on Wednesday morning, the delicate crescent of the old moon will land on the outskirts of the large open star cluster known as the Beehive and Messier 44 in Cancer (the Crab). The best viewing time will occur between about 4:30 and 5:30 am local time. If you place the moon in your binoculars, the cluster’s stars will be sprinkled below the moon (or above it, if you live south of the equator).
(Above: Two views of the old crescent moon’s encounter with the Beehive open star cluster aka Messier 44 in Cancer on Wednesday morning, shown here at 5:30 am local time.)
You can look for the very slim moon sitting low in the eastern sky before sunrise on Thursday morning. On Friday morning at 6:37 am EDT, the moon will reach its new moon phase. When new, the moon is travelling between Earth and the sun. Since sunlight is only reaching the far side of the moon, and the moon is in the same region of the sky as the sun, the moon will be completely hidden from view - from Earth.
The moon’s 27.32-day orbit around Earth is not circular, but elliptical – causing the moon to vary in distance by up to 6% (closer and farther) from the average Earth-moon distance of 385,000 lm. (That variation is responsible for producing occasional “supermoons”.) Because the moon’s closest approach to Earth (perigee) will occur only 5.5 hours after the moon’s new phase, the combined gravitational tugs of the sun and moon pulling from the same direction in space will generate large tides on Earth for several days.
The moon moves across the sky at a pretty high rate of speed – shifting by its diameter every hour. The fresh, young crescent moon will re-appear, low in the western evening sky after sunset, on Saturday evening. If you miss it, try again on Sunday, when the higher and thicker crescent will sit a fist’s diameter to the right (celestial northwest) of the bright star Spica in Virgo (the Maiden) before setting at about 9:30 pm local time.
(Above: On Sunday evening, September 1, the pretty, young crescent moon will appear low in the western post-sunset sky, to the right of the bright star Spica, as shown here at 8:35 pm EDT.)
Jupiter will continue to be the brightest object in the evening sky this week. As the sky begins to darken, look for the giant planet sitting less than a third of the way up the southern sky. Hour by hour, Jupiter will sink lower – then set in the west just after midnight local time. Jupiter is spending this summer above Scorpius (the Scorpion), in the southern part of Ophiuchus (the Serpent-Bearer). I described Ophiuchus, which resembles a huge Dalek from Doctor Who, here.
On a typical night, even a backyard telescope will show you Jupiter’s two main equatorial stripes and its four Galilean moons - Io, Europa, Callisto, and Ganymede looking like small white dots arranged in a rough line flanking the planet. If you see fewer than four dots, then some of them are in front of Jupiter, or hidden behind it. Good binoculars will show the moons, too!
(Above: The bright planets Jupiter and Saturn will continue to dominate the evening sky this week, as shown here at 9 pm local time. The distinctive Teapot and Scorpion are below the planets.)
Over the next few nights, Jupiter will be passing very close to a dim, fuzzy patch of stars - a globular star cluster named NGC 6235 (from the New General Catalogue of deep sky objects). This collection of several hundred thousand stars, arranged by their mutual gravity into a densely packed sphere, is one of many such objects known to orbit our Milky Way galaxy. It is located 38,000 light years away from our solar system! When you see it, you are looking into the distant past. The light from those stars began traveling towards us around the time that Neanderthals died out! Jupiter is overwhelmingly bright compared to the cluster, so try hiding Jupiter just beyond your optics’ field of view. Remember that most telescopes will flip the view around - so check both to the left and right of the planet.
From time to time, the small, round, black shadows cast onto Jupiter’s surface by those four Galilean moons become visible in amateur telescopes as they cross (or transit) Jupiter’s disk. On Wednesday night from dusk to 9:30 pm EDT, observers in the Americas can watch Io’s small shadow transit Jupiter - with the Great Red Spot! On Thursday night from dusk to 9:40 pm EDT, observers in the Americas can watch Ganymede’s shadow transit the northern hemisphere of Jupiter.
Due to Jupiter’s rapid 10-hour rotation period, the Great Red Spot (or GRS) is only observable from Earth every 2nd or 3rd night, and only during a predictable three-hour window. The GRS will be easiest to see using a medium-sized, or larger, aperture telescope on an evening of good seeing (steady air). If you’d like to see the Great Red Spot in your telescope, it will be crossing the planet on Monday evening from dusk to 10 pm EDT, on Wednesday night from 8:40 pm (in twilight) until 11:45 pm EDT, on Friday from 10:20 pm until Jupiter sets, and on Saturday after dusk.
Yellow-tinted Saturn is prominent in the southern evening sky, too - but it is less bright than Jupiter. The ringed planet will be visible from dusk until almost 2:30 am local time. Saturn’s position in the sky is just to the upper left (or celestial east) of the stars that form the teapot-shaped constellation of Sagittarius (the Archer). To find Saturn, look about 3 fist diameters to the left (east) of Jupiter. The Milky Way is between them.
Dust off your telescope! Once the sky is dark, even a small telescope will show Saturn’s rings and several of its brighter moons, especially Titan! Because Saturn’s axis of rotation is tipped about 27° from vertical (a bit more than Earth’s axis), we can see the top surface of its rings, and its moons can arrange themselves above, below, or to either side of the planet. During this week, Titan will migrate counter-clockwise around Saturn, moving from the right of Saturn tonight (Sunday) to the upper left of the planet next Sunday. (Remember that your telescope will flip the view around.)
Tiny, blue Neptune will rise at dusk this week, and then it will climb the eastern sky until it reaches its highest point, due south, at about 2:20 am local time. The planet is among the stars of Aquarius (the Water-Bearer), sitting less than half a finger’s width to the left (celestial east) of a medium-bright star named Phi (φ) Aquarii. Both objects will appear together in the field of view of a telescope. Neptune is actually moving slowly toward that star and will “kiss” it in early September.
(Above: The ice giant planets Uranus and Neptune will soon become evening targets. this view shows them at 11 pm local time.The asteroid labeled (15) Eunomia at upper right is a little bit dimmer than Neptune, but within reach of backyard telescopes.)
Blue-green Uranus will be rising in the east at about 10:30 pm local time this week; and it will remain visible all night long. Uranus is sitting below (celestial south of) the stars of Aries (the Ram) and is just a palm’s width above the head of Cetus (the Whale). At magnitude 5.8, Uranus is actually bright enough to see in binoculars and small telescopes, under dark skies – and it really does look blue! You can use the three modest stars that form the top of the head of the whale (or sea-monster in some tales) to locate Uranus for months to come – that’s because that distant planet moves so slowly in its orbit. To help you find it, I posted a detailed star chart here.
Bright and speedy little Mercury is very low in the east-northeastern pre-dawn sky – but it is descending sunward. Your best opportunity to see it comes early in the week in the minutes surrounding 6 am local time. Venus and Mars are out of action for now. They are snuggling up together in the sun’s glare.
August-September Stargazing Suggestions - Lyra
With the Moon out of the evening sky this week and evening darkness arriving a bit earlier, it’s a good time to tour the night sky.
(Above:The region around the zenith on late August and early September evenings, features the Summer Triangle and the constellations Lyra, the Harp, Cygnus, the Swan, and Aquila, the Eagle. The sky is shown for 10 pm local time.)
Once it’s dark, tilt your head back and look waaay up. Or set out a blanket, gravity chair, or chaise. Point your finger directly overhead. That’s the zenith - the point of the sky directly above you. During the night, various stars and constellations will pass through that patch of sky as the Earth’s rotation carries them from east to west. While objects occupy that position, they will always appear at their best. That’s because you are looking through the thinnest blanket of intervening air. (Light from objects near the horizon has to pass through as much as ten times more turbulent air – making the objects a blurry mess!)
In early evening in early September every year, the constellations of Lyra (the Harp), Cygnus (the Swan), Hercules, and Draco (the Dragon) occupy the zenith. Over the next weeks, we’ll tour them, pointing out some objects you can look at with binoculars and small telescopes. Up first is Lyra. In Greek mythology, Lyra was the musical instrument created from a turtle shell by Hermes and later used by Orpheus in his ill-fated attempt to rescue his lost love Eurydice from the underworld. We Canadian astronomers call Lyra the “Tim Hortons Constellation” because it contains both a doughnut and a double-double coffee!
Facing south and looking just to the lower right of the zenith, you’ll easily spot the very bright star Vega, also known as Alpha Lyrae - the brightest star in the constellation. Vega, the fifth brightest star in the entire night sky - partly because it is only about 25 light years away from us, and partly because it is a very hot, luminous star. The name Vega arises from the Arabic “Al Nasr al Waqi”, or the “swooping eagle”. Traditionally, the Lyre was pictured as being grasped in the talons of an eagle.
Vega is moving towards the Sun and will continually brighten over time, becoming the brightest star in the night sky a few hundred thousand years from now. Meanwhile, the wobble of the Earth’s axis will also cause Vega to displace Polaris as the northern Pole Star. That will happen around 14,500 AD. It was previously the pole star around 12,000 BC. This star is a star!
Vega is also the brightest, highest, and most westerly of the three beautiful, blue-white stars of the Summer Triangle asterism. Moving clockwise, Altair is about three fist widths below and to the left of Vega. Deneb, slightly dimmer than the other two, completes the large triangle at the upper left. The separation between Deneb and Vega is shorter, only 24°, or 2.5 fist widths.
Chinese culture celebrates a love story in which a Cowherd named Niú Láng (牛郎) is the star Altair. Long ago the Cowherd and his two children, (β and γ Aquilae, the stars that flank Altair) were separated from their mother Zhī Nǚ (織女) the “Weaving Girl” (Vega). She is now on the far side of the river, which is represented by the Milky Way. As the story goes, each year, on the seventh day of the seventh month of the Chinese lunisolar calendar, magpies make a bridge across the Milky Way - so that the family can be together again for a single night. Some astronomers believe that the magpies are actually Perseid meteors, which travel parallel to the Milky Way every August.
(Above: A close-up view of Lyra)
Look for a medium-dim star about a finger’s width to the left of Vega. A similarly dim star sits about a finger’s width below it. The three stars form a neat little triangle with Vega on the right. Binoculars or a small telescope will reveal that the triangle’s star to the left of Vega, designated Epsilon Lyrae, is actually a close pair of stars. A really good telescope will reveal that each of the pair of stars is itself a very close together pair! This quadruple star system, or “double-double”, is about 162 light-years from Earth. Even more interesting, each little pair is circling one another, and the two pairs may also be orbiting - in a neat little square dance that takes thousands of years to complete! And that’s your Tim Hortons coffee!
The other corner of our little triangle is the star Zeta Lyrae, and it, too can be split into a double star with binoculars. Both are white and one is slightly brighter than its partner. These stars are about 152 light-years away, and they themselves have partners that are too close together to split visually.
Zeta is also the top right star of a narrow, upright parallelogram about two fingers wide and four fingers tall that forms the rest of the constellation. Moving clockwise, we find Sheliak, Sulafat, and Delta Lyrae. Sheliak, meaning “Harp”, is the brightest of a tight little grouping of stars visible in a telescope. Sheliak itself has a close-in, dim partner that orbits the main star so that, every 13 days, the brighter star is blocked and the total brightness drops by a noticeable amount. This is called an Eclipsing Binary system.
Next, at the bottom of the parallelogram, sits Sulafat, meaning “Turtle”, and named for the shell forming the body of the Lyre. Sulafat is a hot, blue giant star located 620 light-years away. Similar in colour to Vega, Sulafat is much larger - an old star on its way to becoming an orange giant many years from now.
Finally, at the upper left of the parallelogram is Delta Lyrae. Sharp eyes and binoculars will easily reveal that this is yet another pair of stars – one blue (upper) and one red (lower). The two are not related - the blue star is several hundred light-years farther away than the red one. They just happen to appear close together along the same line of sight.
(Above: The famous Double-Double, also known as Epsilon Lyrae sits a finger’s width from the very bright star Vega in Lyra. This view simulates what a telescope will show.)
So, where’s our doughnut? Train your telescope midway between Sheliak and Sulafat, and look for the little, dim, grey smoke ring known as the Ring Nebula (also known as Messier 57). This little bubble of gas in space is the remnant of a dead star of a similar mass to our Sun. These common objects are called planetary nebulae because they exhibit a little round disk, like a planet. Finally, using binoculars or a telescope, sweep to the lower left the line that joins Sheliak to Sulafat. At about twice their separation (from Sulafat) is a Globular Star Cluster called Messier 56. It will appear as a dim fuzzy patch – a Timbit!
Let me know how your exploration of Lyra goes. There are lots of double stars in the constellation.
Public Astro-Themed Events
Taking advantage of dark, moonless evening skies this week, astronomers with the RASC Toronto Centre will gather for dark sky stargazing at Long Sault Conservation Area, northeast of Oshawa on (only) the first clear evening (Monday to Thursday) this week. You don’t need to be a RASC member, or own any equipment, to join them. Check here for details and watch the banner on their homepage or their Facebook page for the GO or NO-GO decision around 5 pm each day.
Every Monday evening, York University’s Allan I. Carswell Observatory runs an online star party - broadcasting views from four telescopes/cameras, answering viewer questions, and taking requests! Details are here. On Wednesday nights they offer free public viewing through their rooftop telescopes. If it’s cloudy, the astronomers give tours and presentations. Details are here.
On Tuesday, August 20, starting at 7 pm, U of T’s AstroTour planetarium show will be Grand Tour of the Cosmos. Find tickets and details here.
If the skies are clear on Thursday evening, September 5, local astronomers will set up their telescopes in Old Thornhill Village. This free event starts at 8 pm and everyone is welcome to come out for a look at the Moon, Jupiter and Saturn, and a variety of deep-sky treasures. The viewing location is Thornhill’s very own “dark-sky oasis,” the Pomona Meadow - situated north of the cemetery on Charles Lane, and east of the Ukrainian Catholic Church of St. Volodymyr. Park for free at the church and just follow the paved path. The rain or cloud date is Thursday, October 3 at 7:00pm. Dress warmly, and we’ll see you there!
On Wednesday, August 28 at 6 pm at U of T’s Bahen Centre for Information Technology, 40 St George St, the Iranian Association at University of Toronto (IAUT) will present A Thousand Nights Under Stars - a lecture by science journalist and NatGeo photographer Babak Tafreshi. To register for this free event, click here.
The next RASC-hosted Night at the David Dunlap Observatory will be on Saturday, September 14. There will be sky tours in the Skylab planetarium room, space crafts, a tour of the giant 74” telescope, and viewing through the 74” and lawn telescopes (weather permitting). The doors will open at 8:30 pm for a 9 pm start. Attendance is by tickets only, available here. If you are a RASC Toronto Centre member and wish to help us at DDO in the future, please fill out the volunteer form here. And to join RASC Toronto Centre, visit this page.
This Fall and Winter, spend a Sunday afternoon in the other dome at the David Dunlap Observatory! On Sunday afternoon, September 15, from noon to 4 pm, join me in my Starlab Digital Planetarium for an interactive journey through the Universe. We’ll tour the night sky and see close-up views of galaxies, nebulas, and star clusters, view our Solar System’s planets and alien exo-planets, land on the moon, Mars - and the Sun, travel home to Earth from the edge of the Universe, hear indigenous starlore, and watch immersive fulldome movies! Ask me your burning questions, and see the answers in a planetarium setting - or sit back and soak it all in. Sessions run continuously between noon and 4 pm. Ticket-holders may arrive any time during the program. The program is suitable for ages 3 and older, and the Starlab planetarium is wheelchair accessible. For tickets, please use this link.
Keep looking up, and enjoy the sky when you do. I love questions and requests - so, send me some!
(Above: On August 26, Jupiter’s orbital motion will carry it across a distant globular star cluster known as NGC 6235. This week, binoculars or a telescope used in a dark sky should show the cluster, sitting less than half a finger’s width east of Jupiter. This simulation shows the event on Wednesday, August 21 at 10 pm local time. For best results, put bright Jupiter just outside your optics’ field of view, and scan both directions from Jupiter to account for the way your telescope flips the image.)
Hello, Summer Stargazers!
Here are your Astronomy Skylights for the week of August 18th, 2019 by Chris Vaughan. Feel free to pass this along to your friends and send me your comments, questions, and suggested topics. I repost these emails with photos at http://astrogeoguy.tumblr.com/ where all the old editions are archived. You can also follow me on Twitter as @astrogeoguy! Unless otherwise noted, all times are Eastern Time. Please click this MailChimp link to subscribe to these emails.
I can bring my Digital Starlab inflatable planetarium to your school or other daytime or evening event. Contact me, and we’ll tour the Universe together!
The Perseids Meteor Shower Peaks!
The prolific Perseids Meteor Shower peaked last Tuesday-Wednesday. The active period for this shower runs until August 26, so keep an eye out for a few stragglers this week. Next year, the moon will once again interfere with this shower. But 2021 will bring us a fantastic, moonless Perseids shower.
The Moon and Planets
This week, the moon will depart the evening sky all over the world while it wanes in phase – leaving our nights darker, and ideal for treasure hunting. Meanwhile, Jupiter and Saturn will continue to put on a show in the southern sky. Here are your Skylights for this week!
For the first few half of this week, the waning gibbous moon (i.e., more than half-illuminated) will rise in late evening and pass through the modest sea constellations of Cetus (the Whale) and Pisces (the Fishes).
In the southern pre-dawn sky on Wednesday, the moon will be positioned a palm’s width below (to the celestial southeast of) the distant, blue-green planet Uranus. Look for a modestly-bright star to the upper left of the moon. That star is Xi Ceti, also known as Al Kaff al Jidhmah (spellings vary). Slow-moving Uranus will remain about four finger widths above (or celestial northeast of) Xi Ceti for the next several months, allowing you to locate Uranus in binoculars and telescopes after the bright moon moves away. (More on this below.)
(Above: The distant ice giant planets Uranus and Neptune are located in the constellations of Aries (centre left) and Aquarius (top right), respectively. Both planets are now late evening and overnight targets. But they will soon be well-placed for evening viewing. The sky is shown at 1 am local time on Wednesday night - when the waning moon will pass by Uranus. Note the main belt asteroid Vesta at lower left.)
On Friday afternoon, the moon will reach its last quarter phase. At last quarter, the moon, half-illuminated on its western side, always rises around midnight local time worldwide and remains visible in the southern sky all morning - or the northern sky, if you live south of the Equator.
When the moon rises at about 12:30 am local time on Friday night, it will be traveling through the stars that form the large, triangular, sideways face of Taurus (the Bull). The very bright, warmly-tinted star positioned about two finger widths below the moon will be Aldebaran. This orange-giant star represents the bull’s eye. To end the week, overnight on Saturday, and into Sunday morning, the waning crescent moon will land near the medium-bright star Zeta Tauri, which marks the lower, eastern horn tip of Taurus.
Jupiter will return to being the brightest object in the evening sky this week. As the sky begins to darken, look for the giant planet sitting less than a third of the way up the southern sky. Hour by hour, Jupiter will sink lower – then set in the west just before 1 am local time. Jupiter is spending this summer in the southern part of Ophiuchus (the Serpent-Bearer). I described Ophiuchus, which resembles a huge Dalek from Doctor Who, here.
On a typical night, even a backyard telescope will show you Jupiter’s two main equatorial stripes and its four Galilean moons - Io, Europa, Callisto, and Ganymede looking like small white dots arranged in a rough line flanking the planet. If you see fewer than four dots, then some of them are in front of Jupiter, or hidden behind it. Good binoculars will show the moons, too!
Here’s a fun exercise on the next clear night once the sky is nice and dark. Grab your binoculars or telescope at low magnification and look just a fraction of a finger’s width to the left (celestial east) of Jupiter for a dim, fuzzy patch. What you are seeing is a globular star cluster, a mass of thousands of stars arranged by their mutual gravity into a densely packed sphere. This cluster, one of hundreds known to orbit our Milky Way galaxy, is named NGC 6235 (from the New General Catalogue of deep sky objects). It is located 38,000 light years away from our solar system! When you see it, you are looking into the distant past. The light from those stars began traveling towards us around the time that Neanderthals died out!
Jupiter is moving steadily towards that cluster, and will pass in front of it next Monday. So the later in the week you look, the closer Jupiter will be to the cluster. Jupiter is overwhelmingly bright compared to the cluster, so try hiding Jupiter just beyond your optics’ field of view. Remember that most telescopes will flip the view around. So check both to the left and right of the planet.
(Above: Situated low in the southern sky, Jupiter and Saturn continue to perform for evening stargazers this week. This year, they are on opposite sides of the Milky Way, as shown here for 10 pm local time.)
From time to time, the small, round, black shadows cast onto Jupiter’s surface by those four Galilean moons become visible in amateur telescopes as they cross (or transit) Jupiter’s disk. On Monday night from 11:02 pm to 1 am EDT, observers in the Americas can watch Io’s small shadow transit Jupiter, although Jupiter will set in the GTA before the transit is complete. On Saturday night from 11:30 pm to 1:55 am EDT, observers in the Americas can watch Europa’s shadow transit the northern hemisphere of Jupiter – but Jupiter will again set during mid-transit for observers in the GTA.
Due to Jupiter’s rapid 10-hour rotation period, the Great Red Spot (or GRS) is only observable from Earth every 2nd or 3rd night, and only during a predictable three-hour window. The GRS will be easiest to see using a medium-sized, or larger, aperture telescope on an evening of good seeing (steady air). If you’d like to see the Great Red Spot in your telescope, it will be crossing the planet tonight (Sunday evening) after 11:15 pm EDT, on Wednesday night from 7:45 pm (in twilight) until 10:45 pm EDT, and on Friday from 9:15 pm to 12:15 am EDT.
Yellow-tinted Saturn is prominent in the southern evening sky, too - but it is less bright than Jupiter. The ringed planet will be visible from dusk until about 3 am local time. Saturn’s position in the sky is just to the upper left (or celestial east) of the stars that form the teapot-shaped constellation of Sagittarius (the Archer). To find Saturn, look about 3 fist diameters to the left (east) of Jupiter. The Milky Way is between them.
Dust off your telescope! Once the sky is dark, even a small telescope will show Saturn’s rings and several of its brighter moons, especially Titan! Because Saturn’s axis of rotation is tipped about 27° from vertical (a bit more than Earth’s axis), we can see the top surface of its rings, and its moons can arrange themselves above, below, or to either side of the planet. During this week, Titan will migrate counter-clockwise around Saturn, moving from the left of Saturn tonight (Sunday) to the right of the planet next Sunday. (Remember that your telescope will flip the view around.)
(Above: For the next few months, you can use the stars that form the top of Cetus’ head to find Uranus, as shown here for midnight local time. The distance from Uranus to the middle of the three stars labelled Al Kaff al Jidhmah measures about 5 degrees, or a slim palm’s width.)
Tiny, blue Neptune will be rising soon after dusk and then it will climb the eastern sky until it reaches its highest point, due south, at about 2:45 am local time. The planet is among the stars of Aquarius (the Water-Bearer), sitting half a finger’s width to the left (east) of a medium-bright star named Phi (φ) Aquarii. Both objects will appear together in the field of view of a telescope. Neptune is actually moving slowly toward that star and will “kiss” it in early September.
Blue-green Uranus will be rising in the east shortly before 11 pm local time this week; and it will be visible all night long. Uranus is sitting below (celestial south of) the stars of Aries (the Ram) and is just a palm’s width above the head of Cetus (the Whale). At magnitude 5.8, Uranus is actually bright enough to see in binoculars and small telescopes, under dark skies.
Because it rises earlier every night, Uranus is transitioning into a good, evening target. As I mentioned above, you can use the three stars that form the top of the head of the whale (or sea-monster in some tales) to locate Uranus for months to come - since the planet moves so slowly in its orbit.
This week, Mercury is low in the east-northeastern pre-dawn sky in Cancer (the Crab) – and below the bright stars of Gemini (the Twins). The planet is now descending sunward again. Your best opportunity to see it this week falls between 5:15 and 6 am local time.
(Above: Mercury is past its prime for the current apparition, but it is still readily visible low in the NNE sky between 5:15 and 6 am local time.)
Venus and Mars are lost in the sun’s glare for the next while.
Some Dark-Sky Delights
With the moon gone and the sky darker, grab your binoculars and tour the Milky Way – from the southern horizon where it rises like steam from the Teapot-shaped stars of Sagittarius (the Archer), overhead through the great Summer Triangle bird constellations of Aquila (the Eagle) and Cygnus (the Swan), and then down to the northeastern horizon - through the W-shaped constellation of Cassiopeia (the Queen).
If you are away from city lights, look for the dark lanes of interstellar dust that divide up the Milky Way. That dust prevents the visible-wavelength light produced by the billions of stars within the plane of our home galaxy from reaching us.
As you scan around, look for bright knots of stars. Larger ones are open star clusters – groups of stellar siblings that have been “recently” born together and are still traveling through the galaxy as a family. (Most stars in the night sky were originally born in groups by the collapse of enormous cold, dark hydrogen clouds.) The small clusters could be open star clusters that are farther away from us, or perhaps, more globular clusters!
Take note of where you find the clusters and look for them on a sky chart - from a magazine like SkyNews, a website, or an astronomy app. I’ll highlight some more delights next week when the moon is approaching its new phase. I’ll post some here.
(Above: The Milky Way in late August rises from the southern horizon near the spout of Sagittarius’ teapot, passes overhead through Aquila, the Eagle and Cygnus, the Swan, and then descends into the NE sky through Cassiopeia, the Queen. this view is for 10 pm local time on August 21, when the moon will rise very late.)
Public Astro-Themed Events
Every Monday evening, York University’s Allan I. Carswell Observatory runs an online star party - broadcasting views from four telescopes/cameras, answering viewer questions, and taking requests! Details are here. On Wednesday nights they offer free public viewing through their rooftop telescopes. If it’s cloudy, the astronomers give tours and presentations. Details are here.
On Tuesday, August 20, starting at 7 pm, U of T’s AstroTour planetarium show will be Our Musical Universe. Find tickets and details here.
If skies are clear on Thursday evening, September 5, my astronomer friends and I will be setting up our big telescope in Old Thornhill Village, starting at 8 pm. Everyone is welcome to come out for a look at the moon, Jupiter and Saturn, and a variety of deep-sky treasures. The viewing location is Thornhill’s very own “dark-sky oasis”, the Pomona Meadow. The meadow is situated north of the cemetery on Charles Lane, and east of the Ukrainian Catholic Church of St. Volodymyr. Park for free at the church and just follow the paved path. The rain or cloud date is Thursday, October 3 at 7 p.m. Dress warmly, and I’ll see you there!
(Above: The site for the Thursday, September 5 Thornhill Village stargazing event is north of John St, and a few hundred metres east of Yonge St.)
The RASC Toronto Centre is running their free, popular six-week introduction to astronomy course called NOVA (New Observers to Visual Astronomy). It is designed to show the novice astronomer the wonders of the night sky and how to enjoy them. It will be held at Yorkville Library from October 15 to November 19, 2019 from 6:15-8:00pm (six consecutive Tuesdays). Classes will be 1 hour and 45 minutes in length, with a 15-minute break in the middle. I teach week five! Spaces will be filled on a first-come first-served basis, and are now open for registration. Click here to go to the registration page.
The next RASC-hosted Night at the David Dunlap Observatory will be on Saturday, September 14. There will be sky tours in the Skylab planetarium room, space crafts, a tour of the giant 74” telescope, and viewing through the 74” and lawn telescopes (weather permitting). The doors will open at 8:30 pm for a 9 pm start. Attendance is by tickets only, available here. If you are a RASC Toronto Centre member and wish to help us at DDO in the future, please fill out the volunteer form here. And to join RASC Toronto Centre, visit this page.
Satellites
There are no visible Iridium Flares or ISS (International Space Station) passes predicted for the GTA this week.
Keep looking up, and enjoy the sky when you do. I love questions and requests - so, send me some!
Hi Chris. I see you write for Star Walk 2. I’m in Australia and am disappointed with the lack of information related to the Southern Hemisphere. Is there any way you can get them to use a more balanced approach? Bill
Hello! Starwalk 2 are using my weekly Skylights blog, which is designed mainly for readers in my part of the world. I do try to use east-west-north-south directions, so that southern hemisphere observers will know where to look, too. I’m not sure if that is what you meant, or if you felt the app itself was missing something. Feel free to contact me at astrogeoguy@gmail.com to discuss this a bit more.
(Above: An amazing image of multiple Perseid meteors, the International Space Station, plus aurora on the northern horizon taken by Bill Longo of Toronto in 2015. http://billlongo.com/)
Hello, Summer Stargazers!
Here are your Astronomy Skylights for the week of August 11th, 2019 by Chris Vaughan. Feel free to pass this along to your friends and send me your comments, questions, and suggested topics. I repost these emails with photos at http://astrogeoguy.tumblr.com/ where all the old editions are archived. You can also follow me on Twitter as @astrogeoguy! Unless otherwise noted, all times are Eastern Time. Please click this MailChimp link to subscribe to these emails.
I can bring my Digital Starlab inflatable planetarium to your school or other daytime or evening event. Contact me, and we’ll tour the Universe together!
The Perseids Meteor Shower Peaks!
The prolific Perseids Meteor Shower peaks from Tuesday night until Wednesday morning before dawn. Within a couple of nights before and after the peak date, the quantity of meteors will be reduced somewhat, but still well worth looking up for. Unfortunately, the moon will be extremely full and bright during the peak this year, so the dimmer meteors will be hidden by the moon-lit sky. Thankfully, Perseids are often very long and bright!
(Above: This brief animated clip of the Perseids Meteor shower was produced by Till Credner. NASA APOD for Sept 8, 2018)
Meteor showers are annual events that occur when the Earth’s orbit passes through zones of debris left by multiple passes of periodic comets. (The analogy would be the material tossed out of a dump truck as it rattles along. The roadway gets pretty dirty if the truck drives the route a number of times!) Over centuries, or longer, the dust-sized and sand-sized (or larger) particles accumulate and spread out a bit. When the Earth encounters them, the particles are caught by our gravity and burn up as they fall through our atmosphere at speeds on the order of 200,000 km/hr. The grains moving that fast through the air generate heat that ionizes the air – producing the long glowing trails we see. The duration of a meteor shower depends on the width of the zone, and the intensity depends on whether we pass through the densest portion, or merely skirt the edges.
The nickname for meteors is “shooting stars” or “falling stars”, but they bear no physical connection to the distant stars, and all your favourite constellations will look the same as ever at the end of the shower!
The source of the Perseids material is thought to be 133-year-period Comet 109P/Swift-Tuttle. The active period for this shower is July 13 through August 26, so keep an eye out for them beyond this week. This shower is known for producing 60-80 meteors per hour at the peak - many manifesting as bright, sputtering fireballs!
While visible anywhere in the night sky, meteors will appear to radiate from a location in the sky (called the radiant) between the constellations of Camelopardalis (the Giraffe) and Perseus (the Hero), which gives this shower its name. The radiant is low in the northeastern sky during mid-August evenings – and nearly overhead by dawn. Meteor showers are best observed in the dark skies before dawn, because that’s the time when the sky overhead is plowing directly into the oncoming debris field, like bugs splatting on a moving car’s windshield. When the radiant constellation is overhead, the entire sky down to the horizon is available for meteors.
The highest Perseid meteor rates this year are expected to occur on from Tuesday night into Wednesday morning August 12-13, when the Earth will be closest to the orbit of comet 109P/Swift-Tuttle and densest part of its debris trail. If you begin to watch after dark on Tuesday evening, you might catch very long meteors that are skimming the Earth’s upper atmosphere. These are fewer, but spectacular. As the night rolls on, the radiant of the meteors will rise higher in the sky, revealing more meteors because they are no longer hidden by the bulk of Earth. The absolute best time to view is around 4 am local time when the radiant will be almost overhead.
(Above: The radiant for the annual Perseids Meteor Shower is in northern Perseus, shown here at 1 am local time this week. But don’t watch for meteors there - any appearing in that area will be the shortest because they are heading directly towards you!)
For best results, try to find a safe viewing location with as much open sky as possible. If you can hide the moon behind a building or tree, that will help. You can start watching as soon as it is dark - to catch very long meteors produced by particles skimming the Earth’s upper atmosphere. These are rarer, but leave very long streaks. Don’t worry about watching the radiant. Meteors from that position will be heading directly towards you and have very short trails.
Bring a blanket for warmth and a chaise to avoid neck strain, plus snacks and drinks. Try to keep watching the sky even when chatting with friends or family – they’ll understand. Call out when you see one; a bit of friendly competition is fun!
Don’t look at your phone or tablet – the bright screen will spoil your dark adaptation. If you can, minimize the brightness or cover the screen with red film. Disabling app notifications will reduce the chances of unexpected bright light, too. And remember that binoculars and telescopes will not help you see meteors because they have fields of view that are too narrow. I’ll post some diagrams here. Good hunting!
The Moon and Planets
This week, the moon will reach its full phase and illuminate the night sky worldwide – to the disappointment of Perseid Meteor Shower viewers. Then the moon will commence its two-week swing back towards the sun. In the meantime, the moon will visit Saturn, and Jupiter will sport spots on Monday and Saturday. Here are your Skylights for this week!
In the southeastern sky after dusk tonight (Sunday), look for the waxing gibbous moon positioned just four finger widths to the right (celestial west) of the bright, yellowish planet Saturn. The pretty duo will cross the sky together for most of the night and will easily appear together within the field of binoculars. If you watch the pair over several hours, starting at dusk, you will see the moon’s orbit carry it closer to the planet while the rotation of the sky lifts Saturn higher than the moon. Observers in eastern Indonesia, most of Australia, northern New Zealand, Melanesia, and Polynesia (except Hawaii) will see the moon occult Saturn on August 12.
(Above: As shown here at 9:30 pm local time, on sunday evening, August 11, the waxing gibbous moon will sit above the Teapot-shaped constellation of Sagittarius, and close to yellowish Saturn. Very bright Jupiter will be about three fist diameters to their right. Note where Saturn is so you can find it again after the moon hops away.)
The August full moon, known as the “Sturgeon Moon”, “Red Moon”, “Green Corn Moon”, and “Grain Moon”, always shines among or near the stars of Aquarius (the Water-Bearer) or Capricornus (the Sea-Goat). Full moons always rise at sunset and set at sunrise. Since this full moon phase will occur in the morning daylight hours of Thursday, the moon will appear to be full on both Wednesday and Thursday evening in the Americas. When full, sunlight is hitting the moon vertically and casting no shadows. All of the variations in brightness we see are generated by differences in the reflectivity, or albedo, of the lunar surface rocks.
On nights around the full moon phase, bright ray features may be seen radiating from the younger craters on the lunar near side. A particularly interesting example of this is the ray system for the crater Proclus. The 28 km wide crater and its ray system are visible in binoculars. They are located at the lower left edge of Mare Crisium, the round, grey basin near the moon’s upper right edge (northeast on the moon). The Proclus rays, about 600 km in length, only appear on the eastern, right-hand side of the crater, and within Mare Crisium, suggesting that the impactor that made them arrived at a shallow angle from the southwest. (Note that east and west are reversed on the moon).
The still-very-bright moon will end the week below the stars of western Pisces (the Fishes), but it won’t rise until late evening and then linger into the morning daytime sky.
Aside from the moon, Jupiter will be the brightest object in the night-time sky this week. As the sky begins to darken, look for the giant planet sitting less than halfway up the southwestern sky. As the evening passes, Jupiter will sink lower, setting in the west just before 1:30 am local time. On Sunday, August 11, Jupiter will end a westerly retrograde loop that began in April, and resume its regular eastward motion with respect to the stars of southern Ophiuchus (the Serpent-Bearer).
The difference in orbital speed between a given planet and Earth generates these predictable, temporary reversals in motion that astronomers call retrograde loops. During Jupiter’s retrograde period, Earth was passing Jupiter “on the inside track” of the Solar System’s “racetrack” around the sun. The stars, which are far beyond the planets, are fixed in place, allowing us to see the planets move among them. The word planet comes from a Greek word for “wanderer”. Take note of Jupiter’s position with respect to the bright, reddish star Antares, which is sitting about a palm’s width to Jupiter’s lower right this summer. If you check back every week or two, Jupiter’s orbital motion will be apparent.
On a typical night, even a backyard telescope will show you Jupiter’s two main equatorial stripes and its four Galilean moons - Io, Europa, Callisto, and Ganymede looking like small white dots arranged in a rough line flanking the planet. If you see fewer than four dots, then some of them are in front of Jupiter, or hidden behind it. Good binoculars will show the moons, too!
From time to time, the small, round, black shadows cast onto Jupiter’s surface by those four Galilean moons become visible in amateur telescopes as they cross (or transit) Jupiter’s disk. On Monday evening from 9:07 to 11:20 pm EDT, observers in the Americas can watch Io’s small shadow transit Jupiter. On Saturday evening from 8:53 to 11:25 pm EDT, observers in the Americas can watch Europa’s shadow transit the northern hemisphere of Jupiter.
(Above: On Monday evening between 9:07 and 11:20 pm EDT, Io’s small, black shadow will cross the disk of Jupiter as shown here at 9:30 pm EDT.)
Due to Jupiter’s rapid 10-hour rotation period, the Great Red Spot (or GRS) is only observable from Earth every 2nd or 3rd night, and only during a predictable three-hour window. The GRS will be easiest to see using a medium-sized, or larger, aperture telescope on an evening of good seeing (steady air). If you’d like to see the Great Red Spot in your telescope, it will be crossing the planet tonight (Sunday evening) from 9:30 pm to 12:30 am EDT, on Tuesday night after 11:30 pm EDT, after dusk on Wednesday and Friday, and after 10:30 pm EDT next Sunday.
Yellow-tinted Saturn is prominent this summer, too - but its less bright than Jupiter. The ringed planet will be visible from dusk until about 3:30 am local time. Saturn’s position in the sky is just to the upper left (celestial east) of the stars that form the teapot-shaped constellation of Sagittarius (the Archer). To find Saturn, look about 3 fist diameters to the left (east) of Jupiter.
Dust off your telescope! Once the sky is dark, even a small telescope will show Saturn’s rings and several of its brighter moons, especially Titan! Because Saturn’s axis of rotation is tipped about 27° from vertical (a bit more than Earth’s axis), we can see the top surface of its rings, and its moons can arrange themselves above, below, or to either side of the planet. During this week, Titan will migrate counter-clockwise around Saturn, moving from the right of Saturn tonight (Sunday) to the left of the planet next Sunday. (Remember that your telescope will flip the view around.)
(Above: The ice giant planets Uranus and Neptune are visible overnight this week, as shown here for midnight local time. The main belt asteroid designated (15) Eunomia, which is at peak brightness for 2019, is at upper right, in Aquarius.)
Tiny, blue Neptune is low in the southeastern sky in late evening, among the stars of Aquarius (the Water-Bearer). The planet will be rising shortly before 9:30 pm local time this week. You’ll find the magnitude 7.8 Neptune sitting half a finger’s width to the left (east) of a medium-bright star named Phi (φ) Aquarii, so both objects will appear together in the field of view of a telescope. The planet is actually moving slowly toward that star and will “kiss” it in early September.
Blue-green Uranus will be rising just after 11 pm local time this week. It is sitting below the stars of Aries (the Ram) and is just a palm’s width above the head of Cetus (the Whale). At magnitude 5.8, Uranus is bright enough to see in binoculars under dark skies, but not this week.
This week, Mercury is in the northeastern pre-dawn sky - below the stars of Gemini (the Twins). After swinging widely away from the sun last week, it will now be descending again. Your best opportunity to see it will land between 5:15 and 5:45 am local time.
(Above: Mercury is at peak visibility in the northeastern sky this week, as shown here at 5:30 am local time on Monday morning.)
Venus and Mars are lost in the sun’s glare for the next while.
Aquila the Eagle
If you missed last week’s information about the constellation of Aquila (the Eagle), I posted it here.
Public Astro-Themed Events
Every Monday evening, York University’s Allan I. Carswell Observatory runs an online star party - broadcasting views from four telescopes/cameras, answering viewer questions, and taking requests! Details are here. On Wednesday nights they offer free public viewing through their rooftop telescopes. If it’s cloudy, the astronomers give tours and presentations. Details are here.
On Wednesday, August 14, starting at 11 am, U of T’s AstroTour planetarium show will be a Kids Summer Break Show. Find tickets and details here.
At 7:30 pm on Wednesday, August 14, the RASC Toronto Centre will hold their free monthly Recreational Astronomy Night Meeting at the Ontario Science Centre, and the public are welcome. Talks include The Sky This Month and funtastic stories of the night sky for public outreach. These meetings are also streamed live on RASC-TC’s YouTube channel. Check here for details. Parking is free.
On Saturday and Sunday, August 17-18, the Ontario Science Centre will present Rockets, Robots & Rovers, exhibits and activities highlighting planetary exploration. Free with admission to the OSC. Details are here.
The next RASC-hosted Night at the David Dunlap Observatory will be on Saturday, August 17. There will be sky tours in the Skylab planetarium room, space crafts, a tour of the giant 74” telescope, and viewing through lawn telescopes (weather permitting). The doors will open at 8:30 pm for a 9 pm start. Attendance is by tickets only, available here. If you are a RASC Toronto Centre member and wish to help us at DDO in the future, please fill out the volunteer form here. And to join RASC Toronto Centre, visit this page.
Keep looking up, and enjoy the sky when you do. I love questions and requests - so, send me some!
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