Discovery of 12 New Jupiter Moons Brings Planet’s Total to 92, Most in Solar System

Feb 8, 2023

With the discovery of a dozen new moons orbiting Jupiter, nine of which are moving in the opposite direction of the planet’s spin, perhaps the gas giant could use a traffic cop.

Their discovery in 2021 and 2022 brings the total number of Jovian moons to 92. Saturn has 83 moons. It held the solar system’s record. 

The new moons are quite small. They range in size from slightly more than a half-mile to two miles in diameter. The moons are located farther out from Jupiter’s surface than its other moons. Their orbits range from more than 340 days to more than 550 days. Astronomers believe the retrograde moons probably didn’t develop near the planet. They say they were likely pulled into its powerful orbit. The retrograde moons revolve around Jupiter in a direction that's opposite to the way the planet spins.  

Most of the solar system’s large moons are prograde. That means they revolve in the same direction as their planets spin. Our moon is prograde.

“I hope we can image one of these outer moons  to better determine their origins,” one scientist told The Associated Press.

The European Space Agency plans to send a spaceship to survey Jupiter and its biggest moons. Those are Callisto, Europa, and Ganymede. Ganymede is bigger than the planet Mercury. Europa is believed to have a huge ice-covered ocean. It might be able to support life. 

In 2024, NASA plans to send the Europa Clipper to conduct as many as 50 flybys of that moon. It is expected to arrive in April 2030.    

Photo by TheLostProbe (Screenshot), Askaniy Anpilogov + FarGetaNik/JaguarJack/Panterstruck (Textures) courtesy of Wikimedia Commons. 

Which quote best captures the main idea of the story? (Common Core RI.5.2; RI.6.2)
a. “In 2024, NASA plans to send the Europa Clipper to conduct as many as 50 flybys of that moon.”
b. “Most of the solar system’s large moons are prograde.”
c. “Their discovery in 2021 and 2022 brings the total number of Jovian moons to 92.”
d. “Saturn has 83 moons.”
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