Educational Focus: Use visibility controls to compare Earth-Moon and Mars-moons systems! See how different orbital periods create unique patterns in space.
The Moon's orbit is elliptical and constantly changing due to the Sun's gravity! The orbital ellipse rotates completely every 8.85 years (apsidal precession), and the eccentricity varies cyclically. The Sun's influence changes the Moon's distance from Earth by several thousand kilometers!
Phobos is one of the fastest-orbiting moons in our solar system! At just 7.6 hours per orbit, it actually orbits Mars faster than Mars rotates (24.6 hours). From Mars' surface, Phobos would rise in the west and set in the east - backwards compared to our Moon!
This simulation demonstrates the famous "three-body problem" in celestial mechanics. The Moon's path around the Sun is always concave toward the Sun - it never loops backward! It's more accurate to think of the Moon as orbiting the Sun with Earth, rather than simply orbiting Earth.
If Earth were the size of a basketball, the Moon would be a tennis ball 23 feet away. Mars would be another basketball 1.3 miles away, with Phobos and Deimos as tiny marbles just inches from Mars. The vast scales of space are mind-boggling!