The Only Moons That Trade Places

The video explores the unique orbital relationship between Saturn's moons Janus and Epimetheus. Discovered in the 1960s, these moons share a one-to-one resonance, switching orbits every four years. Unlike typical celestial bodies in such arrangements, Janus and Epimetheus are similar in size. The Cassini spacecraft provided detailed observations, revealing that these moons are likely rocky rubble piles with craters, possibly contributing to a faint ring around Saturn. Their orbital dance is a rare phenomenon in our solar system.

Who discovered the moon Janus in 1966?

• Richard Walker

• Andois Dolphus

• Galileo Galilei

• Carl Sagan

What is unique about the orbits of Janus and Epimetheus?

• They orbit at different distances from Saturn.

• They are in a one-to-one resonance with similar sizes.

• They orbit in opposite directions.

• One is much larger than the other.

How often do Janus and Epimetheus switch their orbits?

• Every four years

• Every two years

• Every year

• Every six years

What did the Cassini spacecraft discover about Janus and Epimetheus?

• They are piles of rocky rubble.

• They are new moons.

• They have smooth surfaces.

• They are made of ice.

What additional feature did Cassini find that shares the orbit with Janus and Epimetheus?

• A new moon

• A faint ring

• A large asteroid

• A comet