Lovers of the night sky, you’re in luck this week. A waxing Moon and a bright Mars will help you to easily spot Uranus. You just need to have a pair of binoculars or a small telescope handy, or if you're lucky enough to be in a region with exceptionally dark skies, you can attempt to see it with the naked eye.
From January 19-21, Mars and Uranus will be in conjunction meaning their apparent position in the sky will be extremely close. The Moon will be in its first-quarter phase on January 20, so bright but not too bright to outglare the planet. Uranus will be 1.75 degrees south of Mars on January 21, which will be quite bright and visible above the Moon.
So if you want to see the spectacle, just go out after dark and locate the Moon. Just above it, you’ll see Mars as a bright red body. If you look at it with binoculars, you will see Uranus just below it to the left. The Moon will set around midnight, so you won’t even have to stay up late (or wake up early) to catch this celestial event.
Without some optical instrument to help you, it will be very difficult to catch Uranus. It comes down to apparent magnitude, a calibrated value for how bright things appear in the sky. It's estimated that someone with perfect vision somewhere with a dark sky in the middle of the night, will be able to see stars with a magnitude of +6.5. Any value higher would be too dim for our eyes, even under the best possible circumstances.
Uranus is currently at +5.7 magnitude, definitely on the visible side of the magnitude limit for human vision. But since not everyone has the right conditions to spot it, binoculars or a telescope will be your friends. For comparison, Mars is about 150 times brighter.
If you don't catch the conjunction over the next couple of days, you’ll still find the two planets near each other for weeks to come but without the Moon as guidance, it is advisable to use a skymap app to make sure you’re really looking at Uranus.
If this event gives you a taste for planetary conjunctions, or you developed one following Saturn and Jupiter’s Great Conjunction last month, there are a lot of fantastic astronomical events coming your way in 2021, several of them involving Mars!