The Planets
Planet Data For January
Click on any planet below to go straight to its section.
The table below shows key data for the planets this month, including rise, transit and set times, as well as magnitude, apparent size and position data (right ascension and declination).
Events that occur when the sun is below the horizon are shown with a black background and white text. All other events happen when the sun is in the sky and other for not visible for observation.
This is the first – and last, for a while – month where we’re able to see all the planets.
The closest planet to the sun, Mercury, offers a period of sustained good viewing before sunrise in the second half of the month. Venus comes back into view in the evening, while Mars is almost directly overhead later on, but rapidly shrinks and dims as the month passes.
Jupiter remains magnificent, but this is the last really good month for viewing it for a while. Saturn is, sadly, already past its best, and we can only catch it briefly after sunset low on the horizon.
Finally, completing the set, Uranus and Neptune are visible in the evening this month too, which adds a nice little challenge to collect the set.
All of the images below can be opened full screen in a new tab by clicking on them
Mercury
05th January
Mercury sets soon after the sun and is not visible to us. It’s just two days away from passing in front of our star.
15th January
A steep ecliptic in the morning quickly makes Mercury visible once again. Here, at 7am, it’s 6° over the SE horizon.
25th January
At 7am today, Mercury is 10° above the horizon. Its disc is a little over half illuminated.
Mercury passes in front of the sun (inferior conjunction) on 07 January.
Surprisingly, we can see it rather well just a week later, which is all thanks to the steep angle of the ecliptic, which is the line the planets appear to travel on in their journey across the sky. When the ecliptic is steep, Mercury rises a good period before the sun, putting in high in the sky before sunrise.
When you look at it this month, study its disc because we’ll see it fatten as it journeys from being in front of the sun to behind it in the middle of March. In the middle of January, the Mercurian disc is about 20% lit, this will have grown to two-thirds by the time February comes around.
Venus
05th January
About an hour after the sun has set, we’ll see dazzlingly bright Venus just five degrees above the southwest horizon.
15th January
At 6pm ten days later, Venus is twice as high. We’re still viewing it in dusk’s glow, but it shines at magnitude -3.9 and is clearly seen.
25th January
The view at 6:30pm is one where Venus is still 10° high. Its disc is little changed at 92% lit.
Venus comes back to view this month after its trip around the back of the sun at the end of last year.
We don’t have awesome views of it yet but, towards the end of January, we get a serviceable couple of hours to point our telescopes its way after sunset.
The Venusian disc is small but growing, reaching 11 arcseconds across by the end of January. It will appear almost fully illuminated throughout the month, although about 10% of the disc’s surface will be in shadow on the last day of January.
Mars
05th January
At 9pm, Mars is practically overhead. See it between the Pleiades and horns of Taurus the Bull.
15th January
The picture is very similar ten days later. The red planet shines at magnitude -0.7 and its disc has slipped below 13 arcseconds across.
25th January
It’s the same time of day, 9pm, but the planet is moving rapidly away from us. Already its magnitude has slipped to -0.4.
We only get to enjoy the best of the Red Planet for a brief period of time. It was closer to us last December than it’s been for more than two years. Yet, by the end of this month, its best views will already be fading into memory.
As soon as you can in the new year, point your telescope skywards to see the best of this planet. On New Year’s Day, the planet shines at an unmistakably bright magnitude -1.2. Mars is less than 100 million km away from us and its disc is over 14 arcseconds wide.
By the time February is knocking on our doors, Mars has slipped another 30 million km away from us, its disc has, consequently, shrunk to less than 11 arcseconds across and so it shines at only magnitude -0.3.
It’s still bright and large at the end of the month, but it is so much bigger and brighter at the start of 2023 that you should try hard to see it then.
Jupiter
05th January
Jupiter is best seen as soon as darkness falls now. This is the view at 8pm, Jupiter is one-third of the way above the southwest horizon.
15th January
To get a similar view ten days later, it’s best to look at 7pm. The Jovian disc is 37 arcseconds wide, shining at magnitude -2.3.
25th January
Jupiter and the moon have a little dance together this evening in the southwest. This is the scene at 7pm.
It may not be as dramatic as Mars, but Jupiter is certainly slipping away from us.
The massive planet’s disc never shrinks to the pinprick that Mars will become but it does get harder to see as it moves to pass behind the sun. We’re still three months away from that event but already the best time to see Jupiter is as the sky gets dark.
By next month, Jupiter will be transiting in daylight hours. January is, therefore, the last great month for evening observations of this gigantic planet until the fall.
Saturn
05th January
This 6:30pm view of the sky reveals Saturn to already be heading for the horizon. It’ll set just 90 minutes from now.
15th January
Still at 6:30, Saturn is only 12° over the horizon in Capricornus, with Venus nearby. Saturn is much the fainter at magnitude 0.8.
25th January
Another 6:30pm snapshot and Saturn is only half an hour from setting. It is best seen as soon as darkness arrives.
Saturn is slightly ahead of Jupiter in its race to the back of the sun. For this reason, we see the ringed planet all but leave the evening sky this month.
On the last day of January, Saturn sets before seven in the evening, so we only have a couple of dark hours to observe it. Even then, it doesn’t get high enough above the horizon to escape the thicker, murkier air down there.
When we look its way, we’ll see a fifteen arcsecond disc shining at magnitude 0.8.
Enjoy what you can, for it quickly disappears behind the sun in February and we won’t see it again until the early hours of a late March morning.
Uranus & Neptune
15th January – Uranus
This view at 9pm shows Uranus a little over midway between the southwest horizon and overhead point (zenith).
15th January – Neptune
Neptune is better tracked down earlier in the evening. This is the view at 7pm when it will be 30° above the southwest horizon, not so far from Jupiter.
Both of the two most distant planets offer good viewing this month, with each being high above the horizon on the early evening.
Look for Neptune first because it sets earliest, at 10pm in the middle of the month. Uranus doesn’t set until after midnight and is as high as it gets, transiting the southern horizon, a little after 7pm.
All Planets Viewer
Use the table below to see when each of the planets is observable for each day this month. Click on it for full screen.
A planet is classed as observable when it is more than 10° above the horizon and the sky is dark enough for it to be observed.
Planet ephemeris tables produced with the kind permission of Dominic Ford. Sky images are courtesy of SkySafari Pro 6.