The Planets
Planet Data For December
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.
December brings with it the complete set of planets for us to enjoy. Mercury will need an alarm clock setting but Venus, Mars, Jupiter, Saturn, Uranus and Neptune are all visible in the evening.
All of the images below can be opened full screen in a new tab by clicking on them
Mercury
05th December
Mercury passes in front of the sun today (inferior conjunction) and so we’re not able to observe it. This is the view at sunset.
15th December
Ten days later and we’re getting some of the best views of Mercury that we’ve had all year. At 6:30, it’s 11° high.
25th December
At the same time on Christmas morning, Mercury’s about as high as it gets with the sun still below the horizon.
When December starts, it seems like it doesn’t have much to offer us when it comes to Mercury. Heading for inferior conjunction on the 5th, there’s nothing for us to see as it’s so close to the sun.
Yet, come back a week later, and Mercury has left our star so far behind that it will actually become a pleasure to see for the remainder of the month. The ecliptic, the imaginary line that the planets all appear to travel along, is almost perpendicular to the horizon in the morning this December, allowing Mercury to shoot straight up into the sky and leave the sun below the horizon.
If you’re planning to spy it this month, you’re in for a treat as Mercury is just about as high in the sky as it’s possible to get while the sun is below the horizon. Your telescope will reveal that the small, bright disc is only two-thirds illuminated if you look for it around Christmas Day. Viewing stays very good as we say goodbye to 2024.
Venus
05th December
At 6:30 in the evening, with the sky already dark, Venus is 24° high in the west.
15th December
Ten days later, it is slightly higher at the same time and shining at a very bright magnitude -4.2.
25th December
And yet higher again at the same time on Christmas evening. The disc is 2/3rds lit.
Venus offers great evening views this December, glaring with unmistakable brightness in the southwest after sunset. It’s coming closer to us at the moment and we’ll see its disc grow from 17 to 22 arcseconds across this month. At the same time, its getting more and more in front of the sun and so the amount of its disc we see as illuminated is decreasing, from about 2/3rds to just over half.
These two mechanisms, the decreasing disc illumination and increasing disc size, cancel each other out and leave the planet shining with the same dramatic brightness all month long.
Mars
05th December
At last an evening planet again, this is the view at 11pm looking east. Mars is 23° high.
15th December
Ten days later at the same time and now the red planet is over 32° above the eastern horizon.
25th December
When Christmas arrives, we can look for the Red Planet an hour earlier and still see it the same height above the eastern horizon.
By the end of the year, we’ll only have two weeks to wait until Mars reaches opposition, which is when we get the best views of the planet that we’ll have for two years.
In the run up to that event, we’ll see Mars become an observable planet before midnight. We also going to see it grow so quickly that it’ll look splendid in the eyepiece. Over the course of this December, Mars grows from under 12 to over 14 arcseconds wide. Its brightness grows likewise to magnitude -1.4 by the end of December, making it the fourth brightest object in the night sky after the moon, Venus and Jupiter.
Jupiter
05th December
Opposition is just two days away. Jupiter is visible all night and, in this view, is almost 60° high in the east at 10pm.
15th December
At the same time ten days later, Jupiter is still caught between the horns of Taurus the bull.
25th December
As Christmas Day comes to an end, Jupiter is 47 arcseconds wide and near the zenith at 10 pm.
While Mars has a month to go until its big event, Jupiter’s is here now. On the 7th of December, Jupiter reaches opposition, the moment when it is directly ‘opposite’ the sun from our perspective. This is when it is closest, largest and brightest in our night sky. Not only that, but it’s also visible the whole night long.
The Jovian disc is very large – almost fifty arcseconds – meaning we’ll be able to see a lot of details on its surface. Look for it high in the east in late evening, nestled between the horns of Taurus.
Saturn
05th December
At 7pm, we can see Saturn in the south, midway between horizon and zenith.
15th December
The picture looks very similar in the middle of the month at the same time.
25th December
If we look closely we can tell that Saturn is slowly getting closer to the sun, but we’re able to enjoy it throughout December with no issues.
Saturn is steadily returning to the sun and will pass behind it in March next year. This December is the last good month we’ll have for evening views because January sees it rapidly get lower and lower in the sky after sunset.
For now, enjoy the ringed spectacle in your eyepiece in the early evening.
Uranus & Neptune
15th December – Uranus
At 8pm, Uranus is high in the east in the barren space between Cetus and the Pleiades.
15th December – Neptune
At the same time, we’ll be able to find the most distant planet in Pisces. Look southwest at a similar height above the horizon.
Our most distant planets are both visible this month, and at the same time. It’s best to look for them when the moon is not drowning everything out with its brightness, so look at the start or end of the month.
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.