Lysithea’s size and shape
With a radius of about 11 miles, Lysithea is about 350 times smaller than the Earth. With such a small size, Lysithea probably does not have enough gravity to form itself into a sphere and is probably more like an irregular blob shape. Because of Lysithea’s small size, its escape velocity is 50 miles per hour. This means that any spaceship that visits the moon will need to reach this speed to escape Lysithea’s orbit. In comparison, Earth has an escape velocity of 400 miles per hour.
Lysithea’s orbit
Lysithea is the 14th closest moon to Jupiter and orbits at a distance of 7.3 million miles from the planet. At this distance, the moon takes about 259 Earth days to orbit Jupiter. Like the other moons in the Himalia group, Lysithea is in a prograde orbit, meaning that it orbits in the same direction that Jupiter spins. Lysithea’s orbital velocity is around 7,300 miles per hour, which is about ten times slower than Earth’s orbital velocity around the Sun. Because of its orbital properties, Lysithea is known as an irregular moon, meaning it is very different from the regular moons of Jupiter.
Lysithea is in a group of Jupiter moons called the Himalia group
There are seven moons in the Himalia group of Jupiter moons, and Lysithea is the third biggest within this group. This group of moons is named after the moon, Himalia, which is the biggest within this group and has a radius of 50 miles. All of the moons in this group have similar appearance and orbits, so scientists think they come from the same place. Like the Carme group of moons, the Himalia moons are thought to be the result of an asteroid that came too close to Jupiter and was caught in its orbit. The asteroid then collided with another object and broke up into the seven moons in the Himalia group.
Lysithea’s discovery
The Month Wilson Observatory, where Lysithea was discovered, had the largest operational telescope around the time that Lysithea was first discovered. At this same observatory, Edward Hubble discovered that the Andromeda galaxy was not part of our own galaxy. It was also part of experiments to accurately measure the speed of light by observing how beams of light bounced between mirrors on top of nearby mountains.
Lysithea’s future is unknown
The space around Jupiter is crowded with over 80 moons and small objects, some traveling in different directions and at different speeds. Because of this, collisions sometimes happen. Just like the collisions that originally formed Lysithea, its likely another collision will occur within the Himalia group of moons that could affect Lysithea. This might mean Lysithea is only bumped to a different orbit or completely smashed into smaller pieces.