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Europa Moon

by Yule Xie

One of the closest neighbor moons in the solar system is Jupiter’s moon Europa. Europa has an icy surface which means that it reflects light much better than most other planets and moons. Europa was initially discovered by Galileo along with three other famous moons: Io, Ganymede, and Callisto. Although it is very far from Earth, Europa surprisingly shares many similar properties to our own moon. Europa has about 90% the diameter of our Moon, and it also has a similar density and somewhat similar gravity (Europa 1.32 ms-2, Moon 1.6ms-2). However, it has a drastically different orbital period as Jupiter has a much stronger gravity than Earth. While the moon completes an orbit every 28 days, Europa does so in only 3.5. This is also not to mention that Europa’s orbit is actually much farther than the moon: 670,000 km for Europa compared to 380,000 for our moon. This comparison demonstrates the differences in gravitational field between the two planets as despite being further away from its planet, it still obtains a faster orbital velocity.


If we replaced the moon with Europa, the size in the sky would not look so different!


One of the most intriguing things about Europa is that scientists believe that it has an ocean, far deeper than Earth’s, below the ice surface. This is surprising because Europa’s surface temperature can be as low as -180 degrees Celsius, which is far below the freezing point of water. It is possible that the ocean can host simple life forms such as bacteria – which would likely prove for life in other galaxies and stellar systems too. A problem with this, however, is that Europa’s oxygen atmosphere is very weak and the moon often ejects water into space. Something to notice about Europa’s surface is that it contains many stripes, which can stretch across the entire moon and be more than 1,000 km long and 1 km wide. The stripes are actually fractures and craters which formed many millions of years ago.

Like many planets (including Earth), beneath Europa’s possible ocean there is the mantle and core, which is made of iron. 


Sometimes you might wonder, how did all these planets and moons form? Europa formed 4.5 billion years ago when the sun and the solar system was born. Scientists believe that it likely formed from the remaining particles creating its parent planet Jupiter. This is similar to the planets, which formed from the remaining clouds creating the sun.


Although we are not very certain yet about the ocean and life on the moon, science develops every second. Perhaps in the future we will get to visit this enigmatic moon one day.

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