Owners of small telescopes, rejoice! For that matter, on the night of January 21 everyone else can also enjoy the sight of Jupiter and the Moon at nearly the same position on the celestial sphere. Here's our advice on how best to observe this – the closest approach of the Moon and Jupiter until 2026.
On January 21 at 03:02 UTC, the Moon and Jupiter will make a close approach in the constellation of Taurus, being separated by about one Moon's diameter – the actual separation depends on your location. Most of the planet will see the Moon within less than a degree of Jupiter, and South America and a fair bit of the South Pacific will actually see an occultation – that is, they will see Jupiter slip behind the Moon!
The close pairing of Jupiter and the nearly full Moon should present an appealing vista as seen by the unaided eye, but using a pair of binoculars will allow you to see the disk of Jupiter together with the four Galilean satellites (Ganymede, Europa, Io, and Callisto) stretching out to either side of the planet. With a small telescope, the cloud belts of Jupiter can be seen at the same time as the Moon's craters – I suggest using a magnification of 30-40X to see both together in the same field of view.
Where can this unusual pairing of Jupiter and the Moon be seen? Any point of the globe north of Antarctica will see a close approach of the two – simply go outside at about 9pm local time and look up! However, the moment of closest approach (Jan 21 - 03:02 UTC) will only be seen in darkness in the Americas, with daytime observations possible as far west as the Solomon Islands.
Why would you want to look at the pair in the daytime? It is very difficult to see Jupiter during the day, but the close approach gives you a big pointer to Jupiter's position – the Moon. Grab this chance to see another planet during the day.
While conjunctions of the planets and the Moon occur regularly, this is the best pairing which will appear until 2026. Don't wait that long to see a striking astronomical event!
Source: U.S. Naval Observatory