Ganymede is one of the many moons of Jupiter. It is nearly spherical in shape. It is larger than the planet Mercury and slightly smaller than the planet Mars. If it is so large compared with the bodies around it, why is it called a moon and not a planet?
A.
It is too far from the Sun.
B.
It is smaller than Jupiter.
C.
It moves in an orbit around Jupiter.
D.
It has no gravitational pull.
not A: Neptune is farther away
not B: while it is smaller, that is not what "being a moon" is based on
not D: everything exerts gravity
so, try googling "what is a moon?" to further narrow your choices ...
Our Planet of Focus: Jupiter
by Trey Loker
Jupiter is a very interesting planet to study. All of the other planets in our solar system can be packed into Jupiter, with some room to spare! It is also very cold on Jupiter because it is far away from the Sun. If we lived near Jupiter, our skin would turn blue very easily! Along with several other planets, Jupiter has faint rings that encircle the planet. Jupiter’s Great Red Spot is a giant storm with winds over 250 miles per hour! Now that’s a dangerous storm!
Jupiter has been known to humans since ancient times. It can be seen with the naked eye from here on Earth. A man named Galileo was the first to study the planet and discovered Jupiter’s four largest moons. Since Galileo, scientists have been looking at Jupiter’s bright bands of red, orange, and pink for centuries since.
In the last few decades, the United States has begun to send colorful and sturdy spacecraft to Jupiter. Pioneers 10 and 11 were sent to study and observe Jupiter in the 1970s. Later, Voyagers 1 and 2 were launched that discovered even more of Jupiter’s moons. The modern telescopes and spacecraft have continued our understanding of this amazing planet!