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 …
ExploreNew Moon
January 2
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The casual observer
Welcome to the 12th year of The Sky Tonight! This year there big things to look forward to:
- Two total lunar eclipses
- The best opposition of Mars since 2003 occurs at the end of July
- Asteroid 4 Vesta, the brightest asteroid in the sky, also makes a good opposition in June
- It has been 50 years since Apollo 8, when men first saw Earth from afar
- And right at the end of the year New Horizons encounters 2014 MU69, which hadn’t had its new name announced at the time of writing after a public poll was conducted late last year (and no, it won’t be Rocky McRockface…)
Earthrise, as seen by Apollo 8. Credit
January will be the first of three occasions this year where there are five lunar phases in a month. There is a full moon on the 2nd and the 31st of January – and the second one is also a total lunar eclipse! Find out all the details for this event in the feature article below. March also sees two full moons and November will have two last quarter phase moons.
The latest sunset of the summer occurs on the 3rd January, when the Earth reaches perihelion, or the closest point in its orbit to the Sun. However you probably won’t notice the evenings growing noticeably shorter until February – although the time for sunrise should have changed by about half an hour during this time.
Dates of interest
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Earth at perihelion.
January 3
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Mars and Jupiter less than a degree apart, morning sky
January 7
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Mars and brighter Jupiter above the Moon, morning sky
January 12
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Mercury and Saturn less than a degree apart, morning sky
January 13
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Slender crescent Moon to the left of Saturn and Mercury, morning twilight
January 15
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Total lunar eclipse, evening sky
January 31
Planets to look for
2018 starts with no planets in the evening sky. Venus is on the far side of the Sun during January, and in conjunction with the Sun on the 9th. It won’t return to the night sky for several months.
Jupiter and Mars rise together before 2am as the month begins. On the 7th they will be only 0.25 of a degree apart – that is less than half a moon-width, so very close. Jupiter is the brighter of the two, as Mars is still on the far side of the Sun from us. This will change as the year progresses, but for the moment Jupiter still reigns. After the 7th Jupiter will rise earlier than Mars and by the end of January will be rising around midnight.
Usually January is not a good time to see Mercury, but this year the inner-most planet makes a good morning appearance during the first half of January. It rises as the morning twilight starts during the first week and a half, and on the 13th it meets Saturn, also returning to the night sky after its annual time behind the Sun. After this date Mercury will fall back towards the Sun fairly rapidly, and Saturn will climb quickly into darker skies, rising around 3am by month’s end.
Constellation of the month
Auriga the Charioteer
Auriga represents an ancient Greek king who was a famous charioteer. It lies along part of the northern Milky Way and is best seen from Australia during the summer months.
The brightest star in Auriga is Capella, which means the ‘she-goat’. It is actually a pair of giant yellow stars that orbit each other. It lies about 42 light years away, which is pretty close. As seen from southern Australia Capella never gets very high above the northern horizon and is often mistaken for a UFO as it seems to wobble and blink as it goes along – this is just an optical illusion caused by the atmosphere moving about in front of the star. Low down towards the horizon this effect is always more noticeable.
Auriga shares a star with Taurus. Although Auriga is always drawn using this star, it is known as beta Tauri, or Elnath, “the Butting One.” It marks the tip of one of the horns of Taurus.
Object for the small telescope
Messier 41 (M41) is a large open cluster of stars in the belly of the Big Dog, Canis Major. You only need binoculars to find this object, although if you are in a dark enough location you may even be able to see it with the unaided eye. To find it locate Sirius first then move southwards (celestial south, that is, towards the south celestial pole) about 4 degrees (8 moon widths). It has about 100 stars in the cluster and together they span a distance of 26 light years.
Open clusters are groups of stars which all formed together out of the same cloud of dust and gas. Our galaxy is dotted with these star forming regions and we can over 10,000 of them from our vantage place here on Earth.
Total Lunar Eclipse on 31st January
The second full moon of January is also the first of two total lunar eclipses in 2018. Make the most of this one if you can, as it occurs in the evening hours – the next one at the end of July is an early morning event. Lunar eclipses are safe to look at, and you don’t need any special equipment to enjoy them, you just need to go outside and look up!
The west coast will miss out on the early stages of the Moon entering the penumbra, the partial shadow, but there really isn’t much to see at this stage, so it’s not a great loss. The Moon will start to enter the umbra, or full shadow of the Earth, at 7.48 pm WST, and it will take about an hour for the whole of the Moon to move all the way in. By 8.51 pm WST, it should be fully in the umbra, and the part of the Moon furthest in should be starting to show the nice coppery-red colour where the sunlight is being bent around the Earth through the atmosphere. Mid-eclipse is 9.31 pm WST.
The Moon will start to leave the umbra at 10.08 pm WST and will be fully out of the umbra at 11.12 pm WST. The final stage, where it leaves the penumbra, finishes at 12.10am.
For more information go to NASA’s Eclipse Website or EclipseWise
To convert Universal Time (UT) to local time, add 8 hours for Western Australia, add 10 hours if you are in Queensland, or 11 hours if you are in Victoria or New South Wales, because of Daylight Savings.
The Moon showing the coppery-red colour of the umbra, caused by the Earth bending the sunlight around through its atmosphere. It is still bright on one side as it hasn’t quite fully entered into the Earth’s shadow. Photo credit: J. Milner, 4 April 2015
