Jupiter is composed mostly of ________________________. This enormous planet radiates twice as much heat as it absorbs from the ________________________. It also has an extremely strong magnetic ________________________. The planet is slightly flattened at its ________________________ and it bulges out a bit at the equator.

It takes Jupiter 9.8 Earth hours to revolve around its ________________________ (this is a Jovian day). It takes 11.86 Earth years for Jupiter to orbit the Sun once (this is a ________________________ year).

Jupiter's diameter is 88,700 miles (142,800 km). This is a little more than 11 times the diameter of the Earth. Jupiter is so big that all the other planets in our Solar ________________________ could fit inside Jupiter (if it were hollow).

Jupiter's mass is about 318 times the mass of the Earth, but the ________________________ on Jupiter is only about 2.54 times of the gravity on Earth. This is because Jupiter is such a large planet (and the gravitational force a planet exerts upon an object at the planet's surface is proportional to its mass and to the inverse of its radius squared). A 100-pound person would weigh ________________________ pounds on Jupiter.

In ________________________, Galileo first discovered the four largest moons of Jupiter, Io (which is volcanically active), Europa, Ganymede (the largest of Jupiter's moons), and Callisto; these moons are known as the ________________________ moons. Ganymede is the largest ________________________ in the Solar System.