January’s Planet-Palooza
On average and subject to random winter weather systems, January is the coldest month of the year at the latitude of St. Louis. Although the days start to get slightly longer after the December winter solstice, the heat absorbed by the Northern Hemisphere in the summer takes awhile to radiate away. Nevertheless, stargazers who bundle up have a chance to easily spot not one, not two, not three, but four bright planets during convenient evening hours during January, February, and much of March. It really shouldn’t take more than five minutes to spot them all as long as you have fairly open views to the east and west. The fifth and last relatively easily visible naked eye planet can also be found, but you must get up before sunrise to see it during the early part of January.
Venus and Saturn are visible in the southwestern sky after sunset, and will be joined by the Moon early this month
Face west to southwest to spot the first two planets- at around 6 pm, brilliant Venus will be instantly seen. During the first half of January, the next fairly bright “star” to the upper left of Venus will be Saturn. The huge difference in their brightness is due to Venus being about 55 million miles from Earth, about fifteen times closer than the ringed planet. Venus will catch up to Saturn due to its faster motion around the Sun, appearing closest and side by side on the 17h, and then increasingly far above Saturn for the rest of the month. The Moon will pass through the area from January 2-5, as shown below, and again Jan 31-Feb. 1.
Our third and fourth planets are just as easy to spot, but now you must face east. Jupiter dominates this side of the sky-it is not quite as bright as Venus but far outshines any other object. Low in the east at 6 pm, but getting higher as the weeks and hours pass, is Mars. Every 25 months, Earth passes Mars in its race around the Sun, causing the Red Planet to appear in opposition to the Sun, this year on January 16. Mars has a rather eccentric orbit, and if the opposition takes place when it is at its closest point to the Sun, it can come as close as 35 million miles from Earth. Unfortunately, this time Mars will be at best 59 million miles away, and the 2027 and 2029 oppositions will be even a little worse. Even so, Mars will appear just a little dimmer than Jupiter, and appear distinctly orange as opposed to Jupiter’s yellowish white. If you look at the map below, you will see that the moon will be close to Mars at 6 pm on Jan. 13. Just about two hours later, at about 8:02:31 St. Louis time, the Moon will actually cover Mars, an event called an occultation. Bring binoculars or a small telescope- the glare from the Full Moon will cause Mars to be hard to see! Mars will return to view at 9:10:54. In my more than fifty years as a stargazer, I have seen less than half a dozen occultations of planets.
Jupiter and Mars are seen in January’s eastern skies, joined by the Moon from Jan. 10-13.
January also offers a chance to spot the most elusive of the five naked eye planets. Mercury, being the closest planet to the Sun, is often lost in its glare. However, a few times a year it is fairly easy to find if you know when and where to look. To complete your clean sweep of the bright planets, during the first week of January, set your alarm for about 6:15-6:30 am and find a spot with a view low to the eastern horizon. In the glow of early dawn, Mercury will be the only point of light visible low in the eastern sky- binoculars can help you to find it. Don’t confuse Mercury with the star Antares, which will be seen well to the upper right. If you miss Mercury this time, there will be a chance to find it in the evening sky at the end of February and beginning of March.
With sunrises coming late during the winter, you don’t have to get up THAT early to catch January’s morning appearance of the elusive planet Mercury.
The Gateway to the Stars program is scheduled to resume on May 10. Other 2025 dates will be June 7, July 5, August 2, September 27 & October 25. An astronomy or National Park related educational program will precede free telescope viewing of the Moon and other celestial objects.