January 2025
The Sky Tonight - January 2025
January continues the season of Birak, and the hot weather isn’t going anywhere anytime soon. The night sky presents a parade …
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The casual observer
The season of Birak continues into January with no letup of the hot days. At least there are the clear nights and sea breezes.
Speaking of clear nights, in the January night sky we are looking directly away from the bright centre of the Milky Way to the sparser – relatively speaking – outer arms of the galaxy. Orion and his hunting dogs Canis Major and Canis Minor make a good reference point for your stargazing.
Speaking of Orion and nearby constellations, did you know there is a unicorn constellation in the sky? Monoceros is a very faint constellation visible in the northeast during January evenings. Its brightest star Beta Monocerotis comes in at a dim magnitude 3.76 making the constellation challenging to see in light polluted skies, so you may need to use an app to help guide the way. That or you can try finding a real unicorn. You can use Orion and Canis Major and Canis Minor as a reference as Monoceros shares its borders with these constellations on all sides, forming a neat little ring of bright constellations around this very faint one.
Image: Monoceros, bordered by Orion, Canis Major and Canis Minor.
Credit: Stellarium
Speaking of rings, Saturn is finishing the long march across the sky it has been undertaking for the past 6 months and will soon be gone from the evening sky, so this is your last chance to get a good look before it’s gone for a few months. You can find it in the west after sunset as a dim yellowish object and it is joined by the Moon on Jan 14.
Image: Saturn and the Moon on Jan 14 with bright star Fomalhaut as a reference.
Credit: Stellarium
Speaking of the Moon, it passes in front of – or ‘occults’ – the Pleiades cluster (Seven Sisters) on Jan 20. As viewed from Perth, the Moon will block out several of the stars from this cluster over a period of several hours and come very close to the others.
Speaking of close encounters, Mars and Mercury have a close alignment on Jan 28, visible less than ¼ degree apart from each other in the morning sky. The best time to see this is about 4:45 am in the eastern sky just before the Sun rises.
Image: Mercury and Mars close together on the morning of Jan 28.
Credit: Stellarium
Speaking of the Sun, Earth reaches Perihelion on Jan 3. The word Perihelion comes from ancient Greek where ‘peri’ = ‘near’ and ‘Helios’ = ‘Sun’ and fittingly on this day Earth reaches its nearest distance to the Sun on its orbit; a mere 147 100 632 km.
ISS sightings from Perth
The International Space Station passes overhead multiple times a day. Most of these passes are too faint to see but a couple of notable sightings* are:
| Date, time | Appears | Max Height | Disappears | Magnitude | Duration |
| 1 Jan 08:11 PM | 10° above SW | 60° | 13° above NNE | -3.4 | 6 min |
| 20 Jan 04:40 AM | 15° above NW | 82° | 10° above SE | -3.8 | 6 min |
Table: Times and dates to spot the ISS from Perth
Source: Heavens above, Spot the Station
*Note: These predictions are only accurate a few days in advance. Check the sources linked for more precise predictions on the day of your observations.
Dates of interest
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Perihelion
January 3
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Moon close to Saturn
January 14
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Moon close to Jupiter
January 18
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Moon occults Pleiades
January 20
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Close encounter of Mercury and Mars
January 28
Planets to look for
Saturn is visible in the eastern sky after sunset. The planet is in the constellation of Aquarius at the moment, but since the brightest star in Aquarius is the unimpressive magnitude 2.9 star Beta Aquarii, you may find it useful to use nearby magnitude 1.16 Fomalhaut as a reference point to help you find the planet. The Moon passes close by on Jan 14.
Venus is rising in the east about 4am and is joined all month by Mercury and Mars rising slightly later. From Jan 15 onwards they make for good viewing in the east before sunrise along with bright red Antares as well. Be sure to catch the very close approach of Mercury and Mars on Jan 28.
Image: Venus, Mercury and Mars on Jan 15 with Antares visible above.
Credit: Stellarium
Somehow overlooked in all this activity is Jupiter, still glowing brightly in the night sky. Are you looking at a bright object in the northwest in the evening? You are looking at Jupiter.
Constellation of the month
Phoenix
Phoenix is a middle-sized constellation located in the southern skies and, appearing in bird related stories in many mythologies including Arabic and Chinese, is represented by its namesake bird in artistic appearances.
Image: Phoenix is visible in the southwest during January.
Credit: Stellarium
The brightest star in the constellation is the magnitude 2.4 Alpha Phoenicis, an orange giant star about 80 light years away, and is also known as Ankaa, taking inspiration from the Arabic word meaning Phoenix.
The constellation is home to Robert’s Quartet, a group of 4 interacting galaxies about 160 million light years away.
Image: Robert’s Quartet. Note the distorted arm of the spiral galaxy on the left (NGC 92) due to the interactions with the other galaxies.
Credit: ESO
The constellation also contains the notable Phoenix Cluster, a cluster of at least several dozen galaxies about 8.6 billion light years away. The central galaxy in this cluster is the attention-grabbing Phoenix A, a galaxy notable for its furious rate of star formation many hundreds of times faster than the Milky Way, and the enormous super massive black hole at its centre, possibly around 100 billion solar masses (yes, you read that correctly, 100 billion). Some astronomers put such large black holes into their own category called Stupendously Large Black Holes.
Activity around this black hole drives enormous jets of material from the galaxy causing the whole cluster to glow brightly in X rays as one of the brightest objects in the X ray sky. Black hole activity usually heats the gas in a galaxy, making it difficult for the material to come together to form stars, making the extremely high rate of star formation in Phoenix all the more puzzling.
Image: The Phoenix Cluster seen as X rays (blue) superposed on optical image of galaxies.
Credit: X-ray: NASA/CXC/MIT/M.McDonald et al; Optical: NASA/STScI
Observing Phoenix completes our tour of the Southern Birds, made up of Phoenix, Pavo, Grus and Tucana.
Picture: The Southern Birds.
Credit: Stellarium
Object for the small telescope
On Jan 20, as viewed from Perth, the Moon will pass in front of some of the stars making up the Seven Sisters. The event will last from roughly 9pm until about 1am, by which time the Moon and Pleiades will have just set.
Image: Simulated view of the Moon about to pass in front of the Seven Sisters.
Credit: Stellarium
