Look up! It’s the January 2021 Sky Watch! This month, Jupiter and Saturn are still bright in the night sky, Mars reigns in the night, and there’s the chance to spot planet Mercury. See Bob Berman’s highlights of our beautiful January sky and enjoy the wonders of the cosmos!
January 2: Perihelion
January 2 brings an early “perihelion”—when Earth reaches the closest point in its orbit to the Sun in 2021. The word “perihelion” comes from the Greek roots peri meaning near and helios meaning Sun. Why does the Northern Hemisphere have winter weather if it’s closest to the Sun in January? Read about perihelion.
January 2-4: The Quadrantid Meteors
This year, the Quadrantid meteors are expected to peak on the night of the 2nd and morning of the 3rd; in dark skies, about 25 meteors per hour can be seen. Unfortunately, the Quadrantids will be a bit harder to spot than usual this year, since the waning gibbous Moon will be bright enough to outshine most of them. But if you are patient, you should still be able to catch a few good ones. Best viewing will be from a dark location after midnight. Meteors can appear anywhere in the sky. See the Meteor Shower Guide.
Bright Planets of January
Red Mars at Night and Faint Uranus
Mars is the only bright evening planet out during the dark of night, since Jupiter and Saturn are only visible near nightfall until they sink below the horizon. Mars is high in the sky at dusk, and sets in the west about midnight. On January 21 and 21, look for the Moon and the red planet is just above.
- If you have access to binoculars or a telescope, the 20th brings an opportunity to view the distant outer planet Uranus, located right between the Moon and Mars. That evening, find the crescent Moon and the Red Planet in the couple of hours after it gets dark. Starting with Mars, scan the sky towards the Moon and look for the faint, bluish disk of Uranus.
Jupiter and Saturn Remain Paired
Late December brought the historic Jupiter-Saturn Great Conjunction. During the first half of January 2021, the two giant worlds still appear in the sky, but very low near the horizon as the Sun sets.
- During the first half of the month, look west about 45 minutes after the Sun goes down. While Jupiter is bright enough to appear easily in evening twilight, much dimmer and lower Saturn may be hard to spot.
- By mid-month, the two planets set about ½ hour after the Sun. Soon they’ll disappear from the evening sky. Saturn will drop into the Sun’s glare on January 23, 2021 and Jupiter will do the same on January 28, 2021.
See the Almanac planet rise/set calculator.
The Planetary Trio: Triple Conjunction
Mercury now ranks as the second-brightest “star” of the night sky, after Sirius! Usually, the innermost planet of our solar system, named after that swift-footed messenger of the gods, is only observable each year near its greatest separation from the Sun (which falls on January 24 in 2021).
On the evenings of January 9 and 10 (Saturday/Sunday) Mercury will join Jupiter and Saturn to form a triangle—a rare triple-conjunction—just after sunset! This hasn’t happened since 2015. You can start watching on January 8 if you have binoculars, which will be really handy, especially for now dim Saturn. All three objects will fit within the field of view of binoculars.
Since the planets are just a few degrees above the western horizon (about the width of your outstretched fist), you will also need an unobstructed view. If you’re near an ocean, that’s as perfect as it gets!
Here are details on how to see the planetary trio:
- Look west about 45 minutes after sunset (as soon as it gets dark) very low on the horizon in the west-southwest sky.
- Jupiter will become visible first, then Mercury below it. Finally, Saturn—10 times dimmer than Jupiter—will become visible. The three planets will sink from view within 90 minutes of sunset.
- On January 9, Mercury will below both Jupiter and Saturn. Look first for Jupiter which is brightest and highest; Saturn is below Jupiter, and then Mercury is about a thumb’s width (about 1.5º) to the lower left of Saturn.
- On January 10, the best night to see the trio as a planetary triangle, Mercury has moved a little further away from the Sun, appearing about equidistant between Jupiter and Saturn. Jupiter is still positioned at the top of the triangle. Mercury is about two degrees to Saturn’s left.
Credit: Jamie Carter/Forbes. See Jamie’s images for each night of the planetary trio.
- On January 14, look again in the direction of sunset. As dusk ebbs into darkness, see the new and very slender crescent Moon hover above Mercury very low on the horizon! Look for the Moon first which will be “pointing” at Mercury.
January 24, Mercury at Greatest Eastern Elongation
- On January 24, Mercury reaches its greatest eastern elongation of 18.6 degrees from the Sun. This is the best time to view Mercury, since it will be at its highest point above the horizon in the evening sky. Look for the planet low in the western sky just after sunset.
Venus is the Morning “Star”
In the predawn eastern sky, Venus is low but easy to spot. On January 11, get up a little early! Venus is joined by the thin crescent Moon for a striking display. See the Almanac rise/set calculator.
Late January Moon
January 28 brings the full Wolf Moon this year, cresting at 19:18 UTC. See why this full Moon is called the “Wolf Moon.”
Orion the Hunter Reigns in the January Sky
All of Orion’s stars are easy to spot in the winter sky. Let’s do some old-fashioned stargazing and take a look at the Orion constellation!
Sirius, Brightest Star of January
The brightest “star” of the night sky is Sirius, the Dog Star. Ready to star hop? Just look up towards Orion, the Hunter, and his bright belt. Then follow it downward. Orion’s Belt always points to Sirius. Read more about Sirius.
The year 2021 will bring many more wonders! See my take on the Best Astronomy Events for the Year 2021!