Bright Planets Dance on Dark Evenings, the Moon Meets the Scorpion in Morning, and We Tour Taurus!
This amazing composite image by Detlef Hartmann shows the continued expansion of the Crab Nebula Supernova Remnant (aka Messier 1) in Taurus over 10 years (Sept 29, 2008 through Sept 22, 2017). It spans about 0.1 degrees of the sky. In the heart of the nebula sits a rapidly rotating neutron star that emits radio waves. They sweep across our detectors 30 times per second light a fast lighthouse’s beam. The intense radiation causes the gas in the cloud to glow. Detlef’s original image can be viewed at Astrobin https://www.astrobin.com/327338/0/
Hello, late-January Stargazers!
Here are your Astronomy Skylights for the week of January 19th, 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 only shine in the post-midnight and morning daytime sky this week, leaving the evenings worldwide nice and dark for enjoying six planets and the stars and seeing the delights of Taurus, the Bull. Read on for your Skylights!
The Bull’s Best
January evenings feature a group of bright and distinctive constellations that are easy to see, even from the suburbs, and which make winter nights in the Northern Hemisphere worth bundling up and heading outside after dinner on a clear night. The most prominent grouping is the human-like figure of Orion (the Hunter) with his 3-starred belt and bright reddish Betelgeuse sparkling at his shoulder. Orion sits underneath Taurus (the Bull), Auriga (the Charioteer), and Gemini (the Twins). The Winter Milky Way ascends through those four constellations – populating them with countless delights to view in binoculars or backyard telescopes on moonless nights.
The evening skies will be nice and dark this week and next, ideal for stargazing. Taurus sits highest in the sky and is the most westerly of those constellations, so it leads the other ones across the sky. Read on for a tour of the best sights to see in Taurus (the Bull). In future Skylights, we’ll tour its neighbours.
Constellation tours work because they don’t reconfigure themselves from one year to the next – but bright planets passing through them can confuse matters. Only for the winter of 2024-25, the extremely bright planet Jupiter will be gleaming in the stars of Taurus and bright Mars will be shining in Gemini. Jupiter’s 12-year orbit of the sun causes it to shift east by about one zodiac constellation each year. Next year at this time, he’ll be Pollux’ bright belt buckle in next-door Gemini (the Twins). Jupiter is also creeping slowly west through Taurus’ stars night-over-night. In order to make the following tour work regardless of Jupiter’s wanderings, we’ll hop from star to star rather than reference everything to Jupiter’s position.
On mid-January evenings Taurus (the Bull) is located halfway up the southeastern sky after dusk. Then it crosses the sky, shining highest due south around 9 pm local time, and sets in the west around 4 am. Taurus has many wonderful objects to observe in binoculars and through small or large telescopes – including two spectacular star clusters and a supernova remnant!
Taurus’ stars straddle the ecliptic, making it a zodiac constellation that is frequently visited by the sun, moon, and planets. It is also on the north side of the celestial equator, making it visible almost globally. (For reference, Orion’s Belt is almost exactly on the celestial equator.) With the dim constellations of Cetus (the Whale), Aries (the Ram), and Aquarius (the Water-Bearer) positioned just to the west of Taurus (on the right), its much brighter stars pull your attention from them. Taurus is flanked by Orion (the Hunter), Auriga (the Charioteer), and Gemini (the Twins). Being situated on Taurus’ left-hand (eastern) side, they rise later in the evening. Perseus (the Hero) is to the north. To Taurus’ lower right (or celestial southwest) you’ll find the rather faint and winding constellation of Eridanus (the River).
Taurus’ boundary covers a large square on the sky that measures about 3.5 fist diameters on each side – except for its southeastern quadrant, which has been given over to Orion. Taurus is dominated by several elements that combine to make the animal take form. The bull’s face is formed from a large, triangular arrangement of stars. The very bright, orangey-red star named Aldebaran sits at the southeastern (lower left) vertex of the triangle, marking his baleful eye. He’s literally seeing red! Two medium-bright stars that shine 1.5 fist diameters to the left (or 10° east) of his face mark the tips of his horns. A fist’s diameter above the face, the Pleiades star cluster sparkles above his hunched shoulders. To the right (celestial southwest) a handful of less prominent stars form his chest and forelegs. The rest of him is missing. When Taurus rises in the east, he is tilted sideways, with his horns down and legs extended – as if he’s charging the twins of Gemini. His horns don’t point up until he enters the western half of the sky around midnight.
Taurus’ very distinctive shape has been recognized since ancient times, when it was one of the first constellations to be described. At that time, the spring equinox occurred while the sun was in Taurus. (You can see this by setting an astronomy app’s date to local noon on April 9, 2250 BC.) The bull’s strength and fertility were featured in ancient Babylonian and Sumerian myths and legends. In the Mesopotamian Epic of Gilgamesh, the bull was sent to kill Gilgamesh, who is probably represented by Orion’s stars.
In Greek mythology, Taurus represented Zeus in disguise, seeking to abduct lovely Europa who was charmed by the animal’s power and beauty. It may also have been the Cretan Bull which Hercules slew as part of his twelve labours. In the Inuit traditions of the Canadian far north, Aldebaran represents a polar bear, while the rest of the stars in the triangle are dogs keeping him at bay. The Maori view the stars extending from Orion’s Belt upwards through Taurus to the Pleiades as Te Rā o Tainui, the mast and triangular sail of Tainui’s ocean-going war canoe. Other societies interpreted the V-shape of Taurus as a jaw-bone.
Taurus’ triangular face is actually one of the nearest open star clusters to us. Located only about 150 light years away from the sun, it’s called The Hyades, the daughters of Atlas in Greek mythology, who were associated with rain when they wept for their slain brother Hyas. The cluster actually contains several hundred stars, with a half-dozen or so readily seen under moonless, suburban skies. It’s a lovely target to view in binoculars. Many of its stars are close pairs that astronomers call double stars. By the way, Aldebaran is not part of the cluster. It is a foreground star less than half as far away! Astronomers’ designations for the Hyades include Melotte 25, Collinder 50, and Caldwell 41.
There is a remarkable theory that the stars of Taurus, and nearby Orion’s belt, were incorporated into the ancient paintings found on the Caves of Lascaux in Southern France. The paintings were created somewhere between 8,000 and 17,000 years ago. On the ceiling of the Salle des Taureaux or “Room of the Bulls”, are very large color paintings of horned bulls, one of which has dark facial spots approximating the Hyades, plus a grouping of six stars where the Pleiades would be, and a line of stars resembling Orion’s belt. Even the horns are placed where their stars are found. It’s wonderful to imagine early humans documenting the night sky for posterity!
As an alternative to using Jupiter to guide you this year, you can find Taurus anytime by continuing the line formed by Orion’s belt westwards (i.e., upwards in early evening, or to the right later on) by about two outstretched fist diameters (or 20°) until you reach bright Aldebaran. If Orion hasn’t risen yet, you can look high in the east for the little cluster of blue-white stars of the Pleiades and find central Taurus about a fist’s diameter below them (or 12° to the celestial southeast).
Aldebaran, which means “follower” in Arabic because it chases the Pleiades across the sky, is the brightest star in Taurus and is also designated Alpha Tauri (α Tau, for short). It’s an old giant star located 65 light-years away from our solar system. Somewhat cooler than our sun, it’s more than twice as massive and 44 times the sun’s diameter because it has exhausted its core Hydrogen and has swelled in size as it prepares to die. Aldebaran’s position near the ecliptic means that it is frequently occulted (temporarily covered) by the moon and visited by the planets as they traverse their orbits.
If Aldebaran is the bull’s lower eye, the upper eye is marked by the medium-bright yellowish star named Ain or Epsilon Tauri (ε Tau). This winter, Ain is positioned just a few finger widths to the right of Jupiter and the same distance above aldebaran.
The Hyades contains a number of nice double stars. Two degrees to the right of Aldebaran (moving towards the bull’s chin), look with unaided eyes or binoculars for the close-together pair of stars designated Theta 1 and 2 Tauri. The higher one is slightly more yellow. Also easy, on the opposite cheek are three widely spaced stars all designated Delta Tauri. Some apps label them as Hyadum II, Delta 2, and Cleeia or Delta 3. A finger’s width below Aldebaran, hunt with binoculars for the close pair of white stars named Sigma 1 and 2 Tauri. More Hyades’ stars spread well beyond the main triangle.
The beautiful star cluster known as the Pleiades, or the Seven Sisters, which sits about one and a half fist widths above the bull’s face, is one of my favorite wintertime objects. It’s also designated Messier 45 (or M45), part of Charles Messier’s famous list of comet-like objects, and Melotte 22. The Pleiades is made up of the young, hot blue stars named Asterope (“A-STER-oh-pee”), Merope, Electra, Maia, Taygeta, Celaeno, and Alcyone. And those stars are indeed related – born of the same primordial gas cloud. In Greek mythology, they were the daughters of Atlas, and half-sisters of the Hyades. Only five or six of the sister stars are usually seen with unaided eyes. Their parent stars Atlas and Pleione huddle together at the east end of the grouping. Watch for a cute little triangle of stars close beside Alcyone.
Galileo was among the first to observe the Pleiades cluster in a telescope. In 1610, he published a sketch he drew at the eyepiece. The cluster is located about 450 light years away from the sun. Its stars are mainly hot, young, blue-white spectral class B giants and sub-giants that formed together from the same collapsing gas cloud about 100 million years ago. The object is best observed in binoculars or a telescope at low magnification, which can reveal up to 500 stars within a 2° wide field – many of the stars are doubles and multiples. A long exposure photograph, or the view through a very large telescope under dark skies, will also reveal blue nebulosity around the brightest stars – reflected light from unrelated interstellar gas and dust that the stars are passing through. This proper motion will eventually carry the cluster to below Orion’s feet!
Not surprisingly, many cultures, including Aztec, Maori, Sioux, Hindu, and more, have noted this object and developed stories around it. Many indigenous groups saw the Pleiades as the doorway in to the afterlife, or the portal through which humans first fell to Earth. The Anishinaabe call it Bugonagiizhig, the Hole in the Sky. In Japan, it is called Subaru (スバル in katakana), and forms the logo of the eponymous car maker. Due to its similar shape and diminutive size, some people mistake the Pleiades for the Little Dipper. While the shapes are similar, the Little Dipper is twenty times larger than the Seven Sisters!
Jumping well to the left of the Hyades and Aldebaran, and past Jupiter, the star Elnath, or Alnath, which translates to “the butting one”, is an old, bright, hot blue giant star located 130 light-years away from our sun. It marks the bull’s higher (more northerly) horn tip. On the border of Taurus and Auriga (the Charioteer), it’s one of only two stars in the sky that are shared by two constellations. (The other is Alpheratz in Andromeda/Pegasus.)
The bull’s lower horn tip star, which shines a palm’s width below Elnath is less bright, but is still readily seen by eye. It was once referred to as Shurnarkabti-sha-shūtū “the star in the bull towards the south”, but nowadays it’s simply called Zeta Tauri (ζ Tau) or Tianguan in the Stellarium app. This star is a hot blue sub-giant located 420 light-years away, but radiating 6,700 times the light of our sun. Zeta is a candidate to explode one day in a supernova burst – ironic since it sits very close to a supernova remnant, the Crab Nebula, which I’ll tell you more about below.
Starting back at the bull’s chin, let’s sweep to the right (celestial west) to trace out his leg. Lambda Tauri (λ Tau) is a fairly bright star located five degrees to the lower right of the bull’s chin. This is an eclipsing binary variable star that dims in brightness for 1.1 days every 4 days because it has an orbiting dim companion star that blocks some of the main star’s light when it crosses between us and the star. Some apps label it as Elthor “the bull”.
Hopping another fist’s width to the lower right from Lambda brings us to Taurus’ hoofs, marked by the medium bright stars Omicron Tauri and Xi Tauri (or o Tau and ξ Tau). The bright reddish star well to their lower right is Menkar, part of the head of Cetus (the Whale).
Here are a few more interesting objects to hunt for if you have a large telescope and / or very dark rural skies.
The dim star named 47 Tauri sits about a fist’s diameter to the lower right (or 9 degrees to the celestial southwest) of Aldebaran. It’s a close pair of unevenly bright yellow stars.
A thumb’s width to the upper right of Ain, look for faint T Tauri, a very young star recently formed and still surrounded by some of its protostellar disk. That faint fuzzy patch is named Hind’s Variable Nebula.
The supernova remnant now known as the Crab Nebula (or Messier 1) sits a finger’s width above Zeta Tauri. Nowadays, you need a very large telescope to see the remnant as a dim, fuzzy patch – but on July 4, 1054 AD Chinese astronomers recorded that the star that exploded to create the Crab Nebula shone bright enough to see it in the daytime for three weeks! Then it faded to become the brightest night time star for a few months. The object is about 6,500 light-years from our solar system.
Here’s one more treat. A very red, medium-bright magnitude 4.3 star named the Ruby Star (or 119 Tauri) sits 2.7 finger widths to the right of Zeta Tauri, the lower horn tip. It’s a variable star that pulsates every 165 days. You should be able to find and see it easily in binoculars since Zeta and the Ruby Star will share the view.
Smaller open star clusters NGC 1746 and NGC 1647 sit between the bull’s horns. A close-together pair of clusters NGC 1817 and NGC 1807 sit two finger widths below the mid-point of the line connecting Zeta Tauri and Aldebaran. The outer rim of the Milky Way passes just beyond Taurus’ horn tips, and that area will reward scanning with binoculars or telescope, too.
The Moon
The moon will spend this week in the post-midnight sky and remaining visible in the morning daylight while it wanes in illuminated phase. That’s great news for stargazers worldwide!
Tonight (Sunday) the just a little bit gibbous moon will clear the treetops in the east by about 12:30 am local time, surrounded by the stars of Virgo (the Maiden). On Tuesday morning it will shine near Virgo’s brightest star Spica. Then the moon will complete three quarters of its orbit around Earth, measured from the previous new moon, on Tuesday 21 at 3:31 pm EST or 12:31 pm PST, or 20:31 Greenwich Mean Time. At the third quarter (or last quarter) phase the moon appears half-illuminated, on its western, sunward side.
After one more night in Virgo, the waning crescent moon will shine in Libra (the Scales) on Thursday morning. In the southeastern sky before dawn on Friday morning, January 24, the waning crescent moon will be shining among the medium-bright stars that form the claws of Scorpius, barely missing an occultation of the southernmost claw star, Pi Scorpii. The moon’s easterly orbital motion (by about its own diameter every hour) will produce an occultation of Scorpius’ brightest star Antares on Saturday morning for observers located in the Indian Ocean east of Madagascar, including Mauritius and Reunion Islands.
The pretty sight of the moon’s slender crescent will perch above the rooftops in the southeast on Saturday morning. By then in the Americas, Antares will twinkle off to the moon’s upper right. On next Sunday morning, its even slimmer form will appear in the twilit sky before sunrise.
The Planets
If you missed last week’s big Mars and Venus-near-Saturn events, you can still see those planets this week. For those that have been seeing social media posts about a special or rare planetary alignment on January 21 or 25, you can relax – the planets are already gathered in the evening sky and nothing special will happen to them on those dates. In fact, we’ve already had a lot of good nights to see the planets, which are always “aligned” along the ecliptic anyway! Mercury won’t be visible until it joins all the rest of them in evening around the last week of February. Maybe whoever wrote up the original story was confused with Pluto passing the sun at conjunction on Tuesday?
Venus will blaze in the southwestern sky from sunset until it drops into the trees around 9 pm local time. The yellowish dot of Saturn will remain close to Venus in Aquarius (the Water-Bearer) for much of this week. As Saturn and the stars around it shift lower and sunward every night, much closer, and 200 times brighter, Venus will shift increasingly farther above Saturn. Tonight (Sunday) Saturn will appear less than 2 finger widths to Venus’ lower left. They’ll be cozy enough to share the view in binoculars until about Friday, when Venus will have crossed into Pisces (the Fishes).
Viewed in a telescope, Venus 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.
The sky will need to darken a bit before you can spot Saturn. It’s lowering sky position every night will soon end our decent telescopes views of it. Saturn’s bright, but extremely thin rings effectively disappear when they become edge-on to Earth every 15 years. Since we are only 9 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 well to Saturn’s upper left (or celestial east) tonight (Sunday). It will pass below (or celestial south of) the planet from Wednesday to Thursday and then stretch increasingly farther to Saturn’s lower right (or celestial west) 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.
Venus is also travelling closer to the distant and dim, blue planet Neptune, which will be less than a fist’s width to the upper left (or celestial ENE) of Venus this week. Neptune will be visible in a backyard telescope while the moon is gone from early evening.
Three more planets are over in the southeastern sky. After last week’s closest approach and opposition for Mars, the red planet will still be nice and bright while it climbs the evening sky as the bottom member of a conga line below Gemini’s bright almost-twin stars Castor and Pollux. Mars will pass closest to the lower star, Pollux, at mid-week.
At 98 million miles away, Mars is close enough to Earth to show us its bright polar cap and dark patches on its globe through good backyard telescopes. For the best views, wait until the planet has climbed higher after mid-evening. Early risers can see Mars setting in the northwest before sunrise.
Much brighter Jupiter has been dominating the southeastern sky from dusk onward. From now until early February, Jupiter will be creeping west above 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.
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 Monday, Wednesday, and Friday, and also after 10 pm Eastern time on Sunday, Tuesday, Friday, 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 tonight (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, Ganymede and its large shadow will cross the southern latitudes of Jupiter with the great red spot on Monday evening, January 20 between 5:39 pm and 7:49 pm EST (or 225:39 to 00:49 GMT). Io and its shadow will cross Jupiter on Saturday, January 25 between 5:55 pm and 8:03 pm EST (or 22:55 to 01:03 GMT).
The distant ice giant planet Uranus will be observable from the end of evening twilight to beyond midnight. Uranus is located almost two fist diameters to the upper right of Jupiter and 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.
Keep your eyes on the skies! I love getting questions and requests. Send me some!