Solar eclipses on Mars around Mars, the shadow of Phobos was seen in pictures transmitted to Earth. One of these photos was from the NASA rover "Opportunity". Solar eclipses on Mars The two moons of Mars, Phobos and Deimos, are much smaller than the Moon, greatly reducing the frequency of solar eclipses on that planet. Neither moon's apparent diameter is large enough to cover the disk of the sun, and therefore they are annular solar eclipses and can also be considered transits. Due to the small size of Phobos (about ) and its rapid orbital motion, an observer on the surface of Mars would
Galilean moons planet Mercury, though only around half as massive. The three inner moons—Io, Europa, and Ganymede—are in a 4:2:1 orbital resonance with each other. Because of their much smaller size, and therefore weaker self-gravitation, all of Jupiter's remaining moons have irregular forms rather than a spherical shape. The Galilean moons were observed in either 1609 or 1610 when Galileo made improvements to his telescope, which enabled him to observe celestial bodies more distinctly than ever. Galileo's observations showed the importance of the telescope as a tool for astronomers by proving that there were objects in space that cannot be seen by