Europa – the icy moon of Jupiter has a liquid salt-water ocean under its surface and may support life
By Sankalan Baidya
When we talk of Jupiter, we imagine big. So, it is pretty natural for us to think of Europa – one of the many moons of the gas planet as a gigantic celestial body too! However, that’s not really true! Despite its grouping and despite being a natural satellite of the biggest planet in our solar system, Europa is really small. It is surprising right? Well, it came as a surprise to us too! In this article titled 30 Interesting Europa Facts, we are going to explore this interesting celestial body and reveal some of the most surprising facts about it. So, gear up! It is going to get interesting and surprising soon!
Interesting Europa Facts: 1-10
1. Europa is one of 67 moons of Jupiter. It is the 6th largest satellite in entire solar system and the fourth largest satellite of Jupiter.
2. Europa belongs to a group of satellites of Jupiter that are together known as the Galilean Moons. Galileans moons are the largest of all moons of Jupiter and there are 4 satellites in this group.
3. Europa is thus, the smallest moon of the Galilean group of moons. Interestingly enough, despite being the 6th largest, Europa is smaller than the moon of our Earth.
4. Europa was discovered back in 1610 on January 8. The credit for the discovery of Europa is given to Galileo Galilei. However, many experts believe that Simon Marius – an astronomer from Germany, may have discovered the moon around the same time.
5. The Galilean Moons of Jupiter are so called in honor of Galileo. However, Galileo himself gave separate name for the four largest moons of the gaseous planet.
6. In order to honor the Medici family, Galileo named the moons as Medicean Planets despite the fact that they were actually satellites.
7. Many experts think that Galileo actually discovered Europa on 7th of January 1610 (a day before the widely accepted discovery date) but since Galileo was using a self-designed low powered telescope, he thought that Io and Europa were same but later realized that they were two different bodies.
8. It was the discovery of Europa that helped scientists to realize that Earth was not the center of our solar system and that all planets including earth revolves around sun. Interestingly however, as again, westerners take the credit for this realization which first came from ancient Indian astronomer name Aryabhatta, who, in his magnus opus Aryabhaitya actually told that sun lies at the center of the solar system and all planets revolve around it. In case you don’t know, Aryabhatta live in 476-550 CE (if at all the western dates are correct) – more than 1000 years before Galileo even came to existence. Aryabhatta also gave this world the ZERO.
9. Europa derives its name from Greek Mythology where it is said that Europa was the daughter of a king and became a lover of Greek god Zeus. She was made queen of Crete and Zeus fathered several children with Europa.
10. Galileo actually named Europa as Jupiter II thinking that Europa was the second closest moon to the massive planet.
11. Another moon named Amalthea was discovered in 1892. This moon turned out to be closer to Jupiter compared to Europa and hence the name Jupiter II became obsolete, and people started thinking of the Europa as the third closest to the planet.
12. However over time, more moons were discovered, which were closer to the gas giant and as of now, it is accepted that Europa is the 6th moon of the gas giant.
13. Though Galileo actually named the planets with numbers, it was German astronomer Simon Marius who came up with the suggestion of giving individual names to the moons. However, this suggestion was not put in action until 19th century.
14. Scientists think that Europa is 4.5 billion years old – the same age as that of Jupiter.
15. Europa is at an average distance of 780 million kilometers or 485 million miles from sun. From Jupiter however, Europa is located at a distance of 670,900 kilometers or 414,000 miles.
17. Europa is icy cold. The temperature at the polar regions of Europa never goes above -220 degrees Celsius or -370 degrees Fahrenheit. At the equator, the temperature never goes above -160 degrees Celsius or -260 degrees Fahrenheit.
18. The whole crust of Europa is covered in ice. This is which this natural satellite of Jupiter is known to have light reflectivity (or albedo) of 0.64, which is one of the highest for all moons in whole of solar system.
19. One of the most puzzling Europa facts is that though scientists believe that the moon itself is as old as Jupiter, its surface is very young and no older than 20 million years to 180 million years old.
20. If that’s know puzzling enough, you should be surprised to know that scientists believe that deep beneath the icy crust of the moon, there is a massive ocean of salt water which can harbor life.
21. Scientists say that the surface ice is actually frozen ocean water because Europa is way too far from Earth. Also, scientists believe that the liquid water under the icy crust is subject to tidal forces and when Europa is close to Jupiter, the ocean rises above normal and this rising and fall of ocean water beneath the ice crust causes the surface to crack. These cracks are visible.
22. Scientists have actually observed icebergs on the surface of Europa. This observation supports a theory that the liquid water from beneath the icy crust actually explodes out much like lava eruptions and then freeze because of extremely low temperatures.
23. In 2013, the celebrated Hubble Space Telescope spotted something interesting at the poles of Europa. It spotted water vapor geysers that showed up on south pole and then vanished. This has led scientists to believe that this might be a seasonal or cyclical phenomenon.
24. As far as the structure of Europa is concerned, scientists believe that this moon of Jupiter is made of silicate rock and boasts an iron core just like our Earth. They say that the mantle is made up of rocks and that this rocky mantle has a surrounding layer of ice which is nearly 100 kilometers or 62 miles thick.
25. Europa has a very very thin atmosphere. This was discovered by Galileo Mission of NASA. What really happens is that moving molecules in Jupiter’s magnetosphere manages to knock off water molecule from Europa’s surface. On the other hand, charged particles from sun hit these water molecules and separate the hydrogen and oxygen atoms. Hydrogen manages to escape the surface of the moon but the oxygen lingers behind, giving the moon a thin oxygen atmosphere.
26. Europa has a nearly circular orbit. However when Europa comes close to Jupiter, the gravitational pull of the planet slightly distorts the shape of Europa. This is known as tidal flexing. Scientists believe that tidal flexing actually heats up the interior of the moon, allowing it to maintain an ocean of liquid water underneath its icy surface.
27. Europa is known to have smoothest surface among all celestial objects in our solar system. There are no mountains at all but just a few craters. The largest of all the craters is known as Pwyll. There are some other features like freckles, jumbled lenticulae and linae. Scientists think that some of these features were formed water was released from underneath the icy surface.
28. Europa is known to have very high radiation of 5400 mSv. A human being exposed to this radiation just for a single day can lead to very severe illness or even death.
29. Europa, scientists believe, has more water than whole of Earth! Scientists assume that there is about 3 x 1018 cubic meters of water, which is twice the amount of total water present in all water bodies of Earth taken together.
30. One of the most amazing Europa facts is that it is tidally locked to the gas giant. This means that Europa always keeps facing the planet on the same side. Here is another interesting thing. Europa takes 3.551 Earth-days to rotate once on its axis. This means that a day on Europa is equivalent to 3.551 days on Earth. Similarly, Europa also takes 3.551181041 Earth-days to orbit once around Jupiter. This means that one year on Europa is only marginally bigger than one day on Europa. Putting in other words, if you are put on Europa, you will be spending 1 day and one 1 year on Europa in virtually same amount of time!