At last count, Jupiter has 95 moons, but the four main ones — Ganymede, Callisto, Io and Europa — were discovered in 1610 by famed Italian astronomer Galileo Galilei.

Find out what's up in your night sky during July 2025 and how to see it in this Space.com stargazing guide.

When you purchase through links on our site, we may earn an affiliate commission. Here’s how it works. On June 27, 1997, NASA's NEAR Shoemaker spacecraft flew by an asteroid named 253 Mathilde ...