Europa (Moon of Jupiter)

Europa Facts

Galileo Galilei gets the credit for discovering Europa and the other so-called Galilean moons of Jupiter, along with Io, Ganymede and Callisto.

They are among the largest in the solar system.

Europa moon

Europa is the smallest of the four but it is one of the most interesting. Read on to find out more facts about this moon.

The surface of Europa is frozen, covered with a layer of ice. Due to this scientists believe that there could be a very active ocean beneath the surface. Because of its icy surface, Europa has a very strong reflection.

How was Europa Discovered?

  • Galileo Galilei discovered Europa on January 8, 1610. Some people believe that the German astronomer Simon Marius might have also discovered the moon at the same time. But Galileo is the one who is most associated with the discovery. Ever wondered why they’re called Galilean moons? Well it’s due to none other than the fact that they were discovered by Galileo!
  • It is sometimes thought that he might have actually discovered it a day earlier, on January 7, 1610. However, he was using a low-powered telescope so he couldn’t really tell the difference between Europa and Io, one of Jupiter’s other moons. It wasn’t until later that Galileo realized they were two different moons.
  • The discovery of the Galilean moons orbiting Jupiter helped scientists realize that the planets in our solar system, including Earth, revolved around the sun and not the Earth.

planets revolving around sun

How did Europa get its Name? 

  • In Greek mythology, Europa was abducted by Zeus, who had taken the form of a spotless white bull to seduce her. She decorated the “bull” with flowers and rode on its back to Crete. Once in Crete, Zeus — who is a counterpart of the Roman god Jupiter — then transformed back to his original form and Europa was seduced by Zeus. Europa was the queen of Crete and had many children with Zeus.
  • For centuries, the four largest moons of Jupiter didn’t actually have any names.
  • Instead of a name they each got a number from one to four.

moons of Jupiter

  • Europa was believed to be the second closest to Jupiter and was of course called Jupiter II.
  • Then in 1892 Amalthea was discovered, and they found that it was closer to Jupiter than any of the Galilean moons, so they believed that Europa was actually the third closest to Jupiter, instead of the second. That made its name Jupiter II obsolete.
  • Now that even more satellites have been discovered, Europa is now considered at Jupiter’s sixth satellite.
  • Simon Marius was the first who suggested the moons’ current names. However, it wasn’t until the 19th Century that the moons were given the names we know them by today.

Facts about Europa 

Age: Europa is estimated to be about 4.5 billion years old, about the same age of Jupiter.

Distance from the sun: On average, Europa’s distance from the sun is about 485 million miles (or 780 million km).

Distance from Jupiter: Its orbital distance from Jupiter is 414,000 miles (670,900 km). It takes Europa three and a half days to orbit Jupiter. The same side of Europa faces Jupiter at all times.

Europa orbiting Jupiter

Size: Europa is 1,900 miles (3,100 km) in diameter, making it smaller than Earth’s moon, but larger than Pluto. It is the 15th largest body in the solar system, and the smallest of the Galilean moons.

Temperature: Europa’s surface temperature at the equator never rises above -260°F (-160°C). At the poles of the moon, the temperature never rises above -370° F (-220°C).

Features of Europa 

  • A prominent feature of Europa is its high degree of reflectivity, more than any other in the solar system. This is due to its icy crust.
  • Scientists estimate that Europa’s surface is about 20 million to 180 million years old, which actually makes it really young.
  • Through observing pictures taken by the Galileo spacecraft, scientists believe it is made up of silicate rock, and has an iron core and rocky mantle, much like Earth does. Unlike the interior of Earth, however, the rocky interior of Europa is surrounded by a layer of ice that is approximately 62 miles (100km) thick.

Oceans on Europa

  • Experts also think there is an ocean deep beneath the surface of the moon, and that it is possible that there is some form of life there.
  • Many people believe that there is extra-terrestrial life on Europa, and this is one of the reasons that everyone is very interested in this moon.
  • Recent studies show that perhaps Europa could support life!
  • The surface of the moon is covered by a saltwater ocean. As it is so far away from the sun the surface of the ocean is frozen. The surface is also covered with cracks and many believe that this is due to tidal forces from the ocean beneath that massive icy layer.

Europa’s atmosphere

Europa has an atmosphere filled with oxygen. This is probably due to charged particles from the sun hitting the water molecules on the surface, breaking the molecules into oxygen and hydrogen atoms. While the hydrogen escapes the moon’s surface, oxygen is left behind.

Who has Explored Europa? 

  • The Galileo mission, launched by NASA in 1989, is responsible for much of the information we have on Jupiter and the bodies surrounding it. It took more than six years for the unmanned spacecraft to reach its destination. The craft stayed in orbit of Jupiter from December 8, 1995 until September 21, 2003. That’s quite some time!
  • In 2013, the U.S. National Research Council’s Planetary Science Decadal Review issued its 10-year recommendation for NASA’s planetary exploration program. Exploration of Europa was ranked as the highest-priority.
  • Since then, NASA has been working toward a mission to Jupiter’s icy moon.

Europa certainly is an interesting moon. Do you think it could support life or not?

More Resources