by The moon will meet Jupiter, the largest planet in the solar system, for the last time in 2023 on Friday (December 22) when the two celestial bodies make a close approach in the sky. Around the same time, both celestial bodies will have the same right ascension, an arrangement astronomers call a conjunction.
The 10-day-old moon will be 86% illuminated during close approach, with the lit moon face currently waxing as the moon approaches the last full moon of 2023, the December Cold Moon, Tuesday, December 26 .
From New York City, the pre-Christmas meeting between the moon and Jupiter will be visible soon after the two celestial bodies rise above the sky at about 1:18 pm EST (1818 GMT), according to In the sky. The 10-day-old moon will pass only 2 degrees north of Jupiter, and both celestial bodies will be located in the constellation of Aries, the Ram, during the meeting.
The close approach and conjunction of the moon and the largest planet in the solar system will be visible until just before they begin to set around 2:50 am EST (0750 GMT). That means sky watchers will have a few hours to see this conjunction after the sun sets and skies darken at 4:31 pm EST (2131 GMT). Despite this close approach, the moon and Jupiter will still be too widely separated to be seen together in the narrow field of view of a telescope but should be visible together in the wide field of view of binoculars.
Related: The night sky, December 2023: What you see tonight
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Looking for a telescope for next night’s sky event? We recommend the Celestron Astro Fi 102 as the top choice in our best beginners telescope guide.
During the conjunction, the moon will have magnitude -12.5, and Jupiter will be dimmer at magnitude -2.7, with the minus prefix indicating an especially bright object in the sky above Earth.
During the close approach, the moon will dominate Jupiter in the sky in terms of size, but this is only an effect from our perspective from Earth, of course. The moon is much closer to our planet, which is the third planet from the sun, than Jupiter, which is the fifth planet in the solar system, but the second planet greatly exceeds the other in terms of size.
Jupiter is about 89,000 miles (143,000 km) wide, so it is 11 times that of Earth, and our planet is about four times the size of the moon, which has a diameter of about 2,200 miles (3,500 kilometers). That means it would take at least 44 moons to stretch across the diameter of Jupiter.
In fact, the gas giant is so big that it has a moon that is bigger than Earth’s moon and even several planets in the solar system. The largest Jovian moon is Ganymede, which is also the largest moon in the solar system.
With a diameter of 3,270 miles (5,268 km), Ganymede is larger than the dwarf planet Pluto and is even wider than the planet Mercury, which has a diameter of 3,032 miles (4,879 km). Jupiter’s moon, Titan, is also larger than Mercury, but this is due to the fact that its atmosphere is swollen out.
Jupiter is currently about 403 million miles (650 million kilometers) from Earth, which is about 4.32 times the distance between Earth and the sun, and means that light would take about 35 minutes to travel from our planet, past Mars, and to Jupiter .
On the other hand, the moon is 238,855 miles (384,400 kilometers) from Earth, and the gas giant is an average of 444 million miles (715 million km) from our planet. That means the Earth-Moon system would fit within the current distance to Jupiter about 1687 times larger.
When the gas giant is at its closest to Earth, it is still 365 million miles (588 million km) away, and at its furthest, Jupiter is 601 million (967 million km) away. That means the distance to Jupiter changes by 236 million miles, a change in distance alone that is large enough to fit the Earth-Moon system into it by about 988 times!
Although this is the last meeting between the moon and Jupiter this year, the two celestial bodies will soon meet again. The moon will make a close approach to Jupiter on Thursday, January 18, just a week after the first new moon of 2024 and the start of next year’s first full moon cycle.
If you’re looking forward to watching the next conjunction between the moon and Jupiter, our guide to the best telescope and binoculars are best is a great place to start.
If you want to take photos of these celestial objects or the the night sky in general, check our guide on How to make photos on the moon, how to photograph planetsas well as our best cameras for astrophotography and best lenses for astrophotography.
Note to the Editor: If you snap an image of Jupiter’s moon and want to share it with Space.com readers, send your photo(s), your comments, and your name and location to spacephotos@space.com.
