These two odd shaped worlds are the moons of the planet Mars. They are extremely small, only 12.6 km (7.8 miles) and 22.2 km (13.7 miles), respectively. That is smaller than most towns. Their small size causes their gravity to be very weak. Because of this weak gravity they do not have enough force to pull themselves into a round shape. It is thought that these two worlds probably started as asteroids between Mars and Jupiter. However, the powerful gravity of Jupiter probably flung them out near Mars where they were captured eternally by the small red planet.

Phobos (to the right) is a doomed world. Those who live in about 50 million years will never get to see it. Every hundred years it moves almost two meters closer to the surface of Mars. Eventually it will either crash into the planet or be ripped apart, forming a ring like the rings around the outer planets.