Full Wolf Moon Occults Opposition Mars, Venus Smooches Saturn, and Stars Weave the Winter Hexagon!
This terrific image by Sergio Scauso of Villa Maria, Argentina captured Mars just before the moon occulted it on August 9, 2020. NASA APOD for August 15, 2020
Hello, mid-January Stargazers!
Here are your Astronomy Skylights for the week of January 12th, 2025 by Chris Vaughan. Feel free to pass this along to your friends and send me your comments, questions, and suggested topics. You can also follow me on Twitter as @astrogeoguy! Unless otherwise noted, all times are expressed in Eastern Time. To subscribe to these emails please click this MailChimp link.
If you’d like me to bring my Digital Starlab portable inflatable planetarium to your school or other daytime or evening event in Simcoe, Grey, and Bruce Counties, or deliver a virtual session anywhere, contact me through AstroGeo.ca, and we’ll tour the Universe, or the Earth’s interior, together! My book with John A. Read entitled 110 Things to See With a Telescope is a guide to viewing the deep sky objects in the Messier List – for both beginners and seasoned astronomers. DM me to order a signed copy!
The moon will be full on Monday, just in time to occult Mars in the east while that planet is shining brilliantly at its first opposition in more than two years. After that the moon will wane and migrate into morning. Nearby Jupiter will host several shadow transits, and over in the western sky, Venus will finally kiss Saturn after many months of courtship. I also share some information about the giant Winter Hexagon asterism. Read on for your Skylights!
The Moon
For anyone living in North America and western Africa, the full moon will deliver a spectacular occultation of Mars on Monday night and Tuesday morning, respectively. For everyone else, our natural night light will pose close to Mars and its brilliance will make it hard to see anything except the brightest stars and planets. After Monday, the moon will diminish in brightness and shift more into the late-night and pre-dawn sky as it wanes, allowing evening stargazers worldwide to resume our views of the best sights in the January constellations.
As the sun prepares to set tonight (Sunday), the not-quite-full moon will be lifting over the eastern horizon. When the sky darkens more, the bright planets Jupiter and Mars will appear above and below the moon. You can catch their spectacle if you head outside after about 6 pm local time. Once the sky is darker, see how many bright stars you can find around the moon and planets. Binoculars will show plenty of stars, even when the moon is bright.
As I alluded to above, the real fun begins on Monday night. At sunset the full moon will rise with the bright reddish planet Mars. In Europe and Africa, the moon will be several finger widths to the upper right (or celestial west) of Mars. In the Americas, the moon will shine a very short distance from Mars at sunset/moonrise.
The moon will officially reach its full phase on Monday at 5:27 pm EST, 2:27 pm PST, or 22:27 Greenwich Mean Time. Full moons in January always shine in or near the stars of Gemini (the Twins) or Cancer (the Crab). Since they are, by definition, opposite the sun on this day of the lunar month, full moons are always fully illuminated – rising at sunset and setting at sunrise. Full moons during the winter months climb as high in the sky at midnight as the summer noonday sun, and cast shadows in the same locations.
Each society around the world developed its own set of stories for the moon, and every month’s full moon now has one or more nick-names related to human spirit or the natural environment. The Indigenous Ojibwe people of the Great Lakes region call the January full moon Gichi-manidoo Giizis, the “Great Spirit Moon”. (You might recall that name from hearing or singing Henry Wadsworth Longfellow’s The Song of Hiawatha.) For the Ojibwe, January is a time to honour the silence, and recognize one’s place within all of Great Mystery’s creatures.
The Algonquin of the Great Lakes call it Squochee Kesos, “the sun has not strength to thaw” moon. The Haida’s of western Canada and Alaska use Táan Kungáay, the Bear Hunting Moon. The Cree of North America call the January full moon Opawahcikanasis, the “Frost Exploding Moon”, when trees crackle from the extreme cold temperatures. For Europeans, the January full moon is commonly known as the Wolf Moon, Old Moon, or Moon after Yule. The Wolf Moon name might be derived from North American First Nations traditions, although some think it has an Anglo-Saxon origin. In either case, it’s likely that the hungry wolves calling to one another in the dead of winter would leave an impression on anyone before our modern era.
The moon moves east in its orbit by about its own diameter every hour, so later on Monday evening observers across the continental USA, northern Mexico, southern and eastern Canada, and northwestern Africa will be treated to the full moon passing in front of, or occulting, Mars. The event, known as a lunar occultation, can be observed with unaided eyes, binoculars, and through any backyard telescope.
The leading edge (or western limb) of the moon will reach Mars first. The disk of the planet will take 30 seconds or more to become fully blocked by the moon. Mars will remain hidden while the moon moves east, then it will emerge from behind the trailing edge (or eastern limb) of the moon, again over about 30 seconds. Since the moon will be climbing the eastern sky, its orbital motion will be carrying it downwards onto Mars. That means that Mars will be covered by the moon’s bottom and it will emerge somewhere along the top of the moon. The time that Mars remains hidden, and the places along the moon’s edge where Mars disappears and then reappears, varies by your latitude. Generally, the farther south you live, the shorter the occultation will be.
You can use an app like Stellarium or Sky Safari or StarWalk to determine the timings where you live. Watching Mars disappear will be easy, since you’ll easily see the moon creeping closer to Mars. Note that the moon’s glare will hide Mars from your unaided eyes before it’s actually covered by the moon, but binoculars or a telescope will show the event right up until full coverage. The tricky part will be knowing where and when to look to see Mars emerge from behind the moon.
In Toronto, the edge of the moon will cover Mars at 9:17 pm EST. Mars will reappear from behind the moon near the crater Neper at 10:28 pm EST. In Europe and Africa, the occultation will occur before dawn on Tuesday morning. (The emerging location will be different.) Lunar occultations are safe to observe without filters and fun to photograph. Start watching several minutes ahead of your scheduled occultation times.
The waning gibbous moon will rise about 70 minutes later every night after Monday. On Tuesday, it will outshine the stars of Cancer (the Crab) surrounding it. Early risers on Wednesday will see the moon and Mars in the western sky at sunrise. The moon will move in to Leo (the Lion) from Wednesday to Friday, and then join Virgo (the Maiden) for the coming weekend. By then it won’t be clearing the rooftops in the east until after midnight. You’ll be able to see its pale form, the ghost of night, in the southwestern sky during morning.
Winter Hexagon
Sunday night’s bright moon will be completing a passage through a gigantic oval of stars called the Winter Football asterism, also known as the Winter Hexagon and the Winter Circle. The asterism is composed of the brightest stars in the constellations of Canis Major (the Big Dog), Orion (the Hunter), Taurus (the Bull), Auriga (the Charioteer), Gemini (the Twins), and Canis Minor (the Little Dog). Moving counter-clockwise from the bottom of the huge shape, those stars are Sirius, Rigel, Aldebaran, Capella, Castor & Pollux, and Procyon.
The pattern is huge! It will be nearly seven fist diameters (or 70 degrees) high and more than four fists wide in the southeastern sky once Sirius has risen above the rooftops in the southeast around 7:30 pm local time. Later in the evening, the asterism will stand upright in the southern sky. When the bright moon isn’t around, the band of the Milky Way can be seen ascending vertically through the oval. The hexagon is visible during evening from mid-November to spring every year. Jupiter, which is brighter than any of the asterism’s stars, will be spending this winter on the western rim of the football, between Aldebaran and Capella. Bright red Mars will shine on the opposite, eastern edge from now until mid-April. Sunday night’s moon will be completing its monthly trip through the asterism and shining above the Castro, Pollux, and Mars.
The Lakota people of central North America saw a modified version of the pattern called Cangleska Wakan “the Sacred Hoop”. They include the Pleiades cluster, which they call Wicincala Sakowin “Seven Little Girls”. The Sacred Hoop encloses Tayamni, an animal composed of the Pleiades (its head), parts of Orion (its spine and ribs), and the star Sirius (its tail). The boxy stars of Gemini become Mato Tipila “the Bear’s Den”. To them the Sacred Hoop is the stellar embodiment of the “unending circle of time, space, matter, and spirit.”
The Planets
It’s another big week for planets. You may have been seeing posts on social media about a big planetary alignment. That’s largely a nothing-burger that is missing the real treats – Mars at opposition occulted by the full moon and Venus kissing Saturn. Read on!
For several months the planet Venus has been a brilliant beacon in the southwestern sky from sunset and into early evening as its orbit carried it celestial eastward, and farther from the sun. Last Friday it reached the limit of that motion and began to return sunward. This week Venus will be setting around 10 pm local time, about four hours after the sun, offering us plenty of time to enjoy its beauty. Viewed in a telescope, the planet will exhibit an obvious half-illuminated phase. Venus will continue to brighten and increase in apparent disk diameter as it gets closer to Earth ahead of its inferior solar conjunction in late March. For best results, observe Venus during evening twilight when the contrast between the bright planet and the surrounding sky is lower.
Independent of Venus’ orbital dance, the entire sky shifts west by four minutes worth every night, or 28 minutes per week. That’s what causes new constellations to replace the currents ones as time passes. You can see that phenomenon as the planets moving compared to the stars around them. Venus has been among the faint stars of Aquarius (the Water-Bearer) for some time, but you’ll notice a relatively bright “star” near Venus this week – the planet Saturn!
Saturn is far enough from the sun that it, too, is being carried west with the stars from one night to the next. Like trains driving in opposite directions on two tracks, Saturn and Venus will “kiss” in a very close conjunction on Friday. After several months of courtship, Venus will pass only a generous thumb’s width (or 2 degrees) from 200 times fainter Saturn on Friday evening, January 17. The duo will be close enough to share the view in binoculars and backyard telescopes using a low magnification eyepiece. Try to view the conjunction right after dusk, as the planets will be dropping into the trees after 8 pm local time. If Friday is cloudy, you can see them just a bit more widely separated on the surrounding nights.
Saturn’s bright, but extremely thin rings effectively disappear when they become edge-on to Earth every 15 years. Since we are only 10 weeks away from that event on March 23, the rings already appear as a thick line drawn through the planet. Any size of telescope will show the rings and some of Saturn’s larger moons, too. In most years, Saturn’s moons are sprinkled around the planet, unlike Jupiter’s Galileans moons, which are always in a line. But while Earth is within months of being aligned with Saturn’s ring plane, its moons don’t stray very far from the ring plane.
Saturn’s largest and brightest moon Titan “TIE-tan” never wanders more than five times the width of Saturn’s rings from the planet. The much fainter moon named Iapetus “eye-YA-pet-us” can stray up to twelve times the ring width during its 80-day orbit of Saturn. The next brightest moons Rhea “REE-ya”, Dione “Dee-OWN-ee”, Tethys “Teth-EES”, Enceladus “En-SELL-a-dus”, and Mimas “MY-mass” all stay within one ring-width of Saturn. You may be surprised at how many of those six you can see through your telescope if you look closely when the sky is clear, dark, and calm.
During early evening this week, Titan will start from a position to Saturn’s lower right (or celestial west) tonight (Sunday). It will pass above (or celestial north of) the planet from Tuesday to Wednesday and then stretch increasingly farther to Saturn’s upper left (or celestial east) by next Sunday. (Remember that your telescope will probably flip the view around.) The rest of the moons will be tiny specks in a line near the rings. Earth’s perspective of the Saturn system will also cause Saturn’s moons and their small black shadows to frequently cross its disk – but you’ll need a very high quality telescope to watch those.
The distant and dim, blue planet Neptune will be about Neptune 1.1 fist widths to the upper left (or celestial ENE) of Venus and Saturn this week. Neptune will be easier to see in a backyard telescope late this week and next while the moon is gone from early evening.
The other fantastic planet action will be happening over in the eastern sky.
We are experiencing our best views of Mars in more than two years! Mars was closest to Earth this morning, but it will look extra-good in any backyard telescope for the next couple of weeks. If your skies are clear on Monday night, we’ll see a rare treat of the full moon occulting Mars, as I described above.
The show will climax when Mars reaches opposition at 10 pm EST on Wednesday, January 15. On that night, the bright red planet will rise below the bright stars Pollux and Castor in Gemini at sunset, climb to its highest position due south around midnight local time, and then set in the west at sunrise. The moon and Mars will cross the sky all night long after the occultation.
On opposition night, Mars will shine with a peak visual magnitude of -1.38. Although its distance from Earth of 96.29 million km, 0.644 AU, or 5.35 light-minutes will be slightly farther than it was at closest approach on Friday, Mars will still be an impressive sight in backyard telescopes for some time, showing an apparent disk diameter of 14.55 arc-seconds. (In comparison, Jupiter’s disk spans about 42 arc-seconds.)
Mars’ Earth-facing hemisphere on Friday will display its bright northern polar cap – visible as a small bright spot along the planet’s edge, as well as the dark Aurorae Planum, Acidalia Planitia, Meridiani Planum, Terra Sabaea, Syrtis Major Planitia regions, and the lighter-toned Chryse Planitia and Arabia Terra regions. Mars takes about 20 minutes longer than Earth to rotate once fully on its axis. So viewing the planet at the same local time on subsequent nights will show roughly the same view of it, with its surface markings turned by about 5°. If you have coloured filters for your telescope, see if the blue, orange, or red one improves the view.
Mars oppositions occur approximately every 25.5 months. The difference in the opposition and the closest to Earth dates arises because the distance between Earth’s and Mars’ elliptical orbits is widening at this part of Earth’s year since Mars’ orbit is more elliptical than Earth’s. If it’s cloudy on Wednesday use the next available night for your peek at it. Mars will be slightly farther from Earth at its next opposition in February, 2027. It won’t be this close to Earth until June, 2033! The August 15, 2050 Mars opposition will be closest of all – only 56 million km, yielding a 25 arc-seconds wide disk!
Jupiter has been dominating the eastern sky after dusk. From now until early February, Jupiter will be creeping west towards the stars that form the triangular face of Taurus (the Bull) and Taurus’ brightest star, reddish Aldebaran, which marks the eye of the beast at the lower corner of the triangle. This week, Jupiter and Aldebaran will be less than a palm’s width apart. The winter constellations will rise below Jupiter every evening. By the time the clock strikes midnight, those constellations will have rotated to the planet’s left. The stars will be easier to see once the bright moon shifts into the post-midnight sky later this week.
Viewed in any size of telescope, Jupiter will display a large disk striped with brown dark belts and creamy light zones, both aligned parallel to its equator. With a better grade of optics, Jupiter’s Great Red Spot, a cyclonic storm that has raged for hundreds of years, becomes visible for several hours when it crosses the planet every 2nd or 3rd night. For observers in the Americas, that GRS will cross Jupiter’s disk during early evening on Sunday, Wednesday, and Friday, and also after 10 pm Eastern time on Sunday, Tuesday, Thursday, and next Sunday night. If you have any coloured filters or nebula filters for your telescope, try enhancing the spot with them.
Any size of binoculars will show you Jupiter’s four Galilean moons named Io, Europa, Ganymede, and Callisto lined up beside the planet. Those moons complete orbits of the planet every 1.7, 3.6, 7.2, and 16.7 days, respectively. If you see fewer than four moons, then one or more of them is crossing in front of or behind Jupiter, or hiding in Jupiter’s dark shadow – or two of the moons are very close together, or one moon is eclipsing or occulting another one. All four moons will gather to one side next Sunday.
From time to time, observers with good quality telescopes can watch the black shadows of the Galilean moons travel across Jupiter’s disk. In the Americas, Europa and its little shadow will cross Jupiter on Tuesday morning, January 14 between 12:28 am and 3:00 am EST (or 05:28 to 08:00 GMT on Wednesday). Io and its good-sized shadow will cross Jupiter on Thursday, January 16 between 9:31 pm and 11:40 pm EST (or 02:31 to 04:40 GMT on Friday).
To round out the planets, the distant ice giant planet Uranus will be observable all night long after the bright moon departs later this week. Uranus is located in the eastern early evening sky about a palm’s width to the right (or celestial southwest) of the bright little Pleiades star cluster in Taurus (the Bull). If you use your binoculars to find the medium-bright stars named Botein and Epsilon Arietis, Uranus will be the dull-looking blue-green “star” located several finger widths below (or southeast of) them. To get you in the vicinity of Uranus, look for the bright star Menkar shining 2.2 fist diameters off to the right of the Pleiades and down a little. Uranus will be a quarter of the way along the line joining the bottom star of the Pleiades to Menkar. In late evening, Uranus will be below the Pleiades in the southwestern sky.
Public Astronomy-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. They host in-person viewing on the first clear Wednesday night each month. Other Wednesdays they stream views online via the observatory YouTube channel. Details are here.
At 7:30 pm on Wednesday, January 15, the RASC Toronto Centre will livestream their free monthly Speaker’s Night Meeting. The speaker will be Dr. Samantha Lawler, Associate Professor of Astronomy, University of Regina. Her topic will be Space Debris Falling on Saskatchewan: Fallout from the Billionaire Space Race. Check here for details and watch the presentation at https://www.youtube.com/rasctoronto/live.
On Friday, January 17 from 6:30 to 8:30 pm EST, the public are invited to visit the David Dunlap Observatory for Mars Madness. They’ll have special guests, live views of Mars through members’ telescopes, and fun activities. This is a rain or shine event. The giant telescope will not be open. More information can be found here and the link for tickets is at ActiveRH.
Keep your eyes on the skies! I love getting questions and requests. Send me some!