On November 25, 2020, the waxing gibbous Moon will rise in tandem with the Red Planet. In today’s article, we’ll talk about the two astronomical terms that can describe this phenomenon and tell you how to find the beautiful duo in the sky above you.
Appulses and conjunctions
When two celestial objects make a close approach in the sky, astronomers may use two related terms that we should differentiate between: appulse and conjunction. An appulse designates the minimum apparent separation between two bodies in the sky. A conjunction happens when two astronomical objects share the same right ascension — the celestial equivalent of terrestrial longitude. In general, the precise time of an appulse will be different from that of a conjunction. In some cases, an appulse might occur without a conjunction.
Close approach of the Moon and Mars
On November 25, at 19:46 GMT, the conjunction of the Moon and Mars will occur, as Mars will have the same right ascension as the 10-days-old Moon. During the conjunction, the Moon will be glowing at a magnitude -12.3 in the constellation Cetus, and Mars will be shining at a magnitude -1.3 in the neighbouring constellation of Pisces. A bit later, at 23:59 GMT of the same day, an appulse will also happen — the Moon will make the closest apparent approach to Mars, passing within 4°27' from the Red Planet.
Note that while we’re giving you the precise time of the conjunction and appulse, it doesn’t mean this is the only time you can see the close approach of the two objects. You can observe the Moon and Mars shining together on the night of November 25 until they both sink beneath the horizon. Moreover, on the days surrounding this date, the Moon will also be quite close to the Red Planet, so you can enjoy this duo three nights in a row!
How to find the Moon and Mars in the sky
Locating the Moon and Mars rising in tandem in the sky above you is pretty easy. The Moon is the brightest object in the night sky, so you won’t need any special knowledge to find it. To locate red-glowing Mars, use the Star Walk 2 app. Tap the magnifier icon in the lower-left corner of the screen, type in “Mars”, tap the corresponding search result, and you will see its exact location. Now, tap the compass icon in the upper-left corner and follow the white arrow. In the sky, Mars will look like a bright reddish dot shining close to our natural satellite. You can observe the celestial duo with the naked eye, but it will also fit nicely in the field of view of binoculars.