Jupiter's moon, Europa.
This photo was taken close by by Jupiter probe Juno on September 29, 2022. At that time, it was only about 1,500 kilometers away from the surface of Europa, so it showed many details of the surface of Europa.
Europa surface details
Europa surface details
Europa surface stripes and spots that resemble footprints
Europa origin
Europa is also called Europa . It sounds like it is Jupiter's second satellite, but it is not. Europa's name is because of Galileo's discovery at that time.
Galileo was the first to discover that there were 4 moons of Jupiter on January 8, 1610.
Four moons of Jupiter drawn by Galileo
In fact, we can also see with astronomical telescopes that there are four highlights around Jupiter. The four highlights of
were Galileo's discovery at that time, so we also call these four satellites: Galileo satellite .
So at that time, people had not discovered other satellites, and they thought they were the second closest to Jupiter, so they called it Europa. But then, in September 1892, American astronomer Barnard discovered a satellite closer to Jupiter than Europa, Amalthea .
Barnard
1979 Amalthea
1979 When Voyager flew over Jupiter at close range, he discovered three other moons closer to Jupiter than Europa.
Jupiter's innermost four satellites, the third from left is Amalthea
So at this point, Europa became Jupiter's sixth satellite .
So Europa's name is that we continue Galileo's discovery at that time.
This is the Amalthea
Europa basic information
Jupiter has discovered eighty satellites (57 of which have been named, and 23 are not named). Among these eighty satellites, the first four satellites are Io, Europa, Io, and Io, which are the Galileo satellites.
Galileo satellite
Among them, Io is the largest. Io Veteran is actually the largest satellite of the sun. Its diameter reaches 5268 kilometers
Moon, comparison between Io Veteran (bottom left) and the earth
Euro Veteran photographed by Juneau in 2021 is the smallest of Jupiter Galileo satellite. It takes about three and a half days to rotate around Jupiter.
Moon, Europa (bottom left) and the earth
Like the moon, Europa has also been tidally locked, that is, it always faces Jupiter on one side, and the density of Europa is similar to that of the earth, which shows that its composition is mainly silicate rock structure, but its surface is covered by a thick layer of ice.
The surface temperature of Europa is averaged minus 170℃. In such an environment, the ice layer here is very hard, but liquid water may exist under the hard ice layer.
Europa internal structure
Europa detection
Humans' most in-depth detection of Europa started with the Voyager detection in 1979, followed by the Galileo and Juno .
1979, the close-up of the surface of Europa, taken by Voyager 2 in 1979,
1998, the detection of Europa, taken by Galileo in 1998, the detection of Europa, taken by Galileo in 1997, the detection of Europa, allowed us to see the details of these stripes and the broken ice shells on the surface.
The stripes on the surface of Europa look like cracks. The reason for their formation may be the cracking and refusion of the ice layer on the surface of Europa.
Galileo Detector
Galileo Detector was launched on October 18, 1989 and flew for 7 years after launch. It came to Jupiter's orbit in 1996 and fell into Jupiter in 2003, so the detection of Jupiter lasted for about 8 years.
Juno was launched in 2011 and arrived near Jupiter in 2016. It is still under investigation.
Through Galileo's detection, we also found that in addition to the characteristics of stripes, the surface of Europa is much smoother than other satellites, that is, its surface lacks large-scale features such as mountains, gullies and craters.
However, a 2018 study showed that in parts of Europa, there may be jagged ice thorns, which are estimated to be as high as 15 meters, but there is no direct visual evidence at this time. Another discovery of Galileo on Earth's surface is that it detects the presence of a plume jet, but this was a review in 2018 to determine the suspected plume shot by Hubble in 2016.
Plumed jet art detected by Galileo
In 2016, Hubble photographed that Europa suspected of having a pinned jet, which was at this seven o'clock. The plume jet like
is very similar to the plume of Enceladus detected by Cassini in 2015.
Enceladus plume taken by Cassini
Therefore, if Europa also has such plume, then there should be a liquid ocean under its ice layer.
This is the current consensus among astronomers on Europa.
so the ocean, plus the heat source created by tidal forces, some researchers believe that under the ice of Europa is the condition that life can be nurtured, just like the deep bottom of the Earth's seabed.
But because Galileo and Juno are not detectors that specifically detect Europa, they are just simple flights. Therefore, we still have many problems with Europa's liquid ocean and surface ice thorns.
However, in the future, it is expected that in October 2024, NASA may launch a detector called Europa Clippers. This detector will make targeted explorations of Europa. At the same time, it will also explore the surface to find suitable locations for future landers to land, so as to detect the world under the ice.
At that time, maybe we will have a great discovery about Europa.
OK, this is some research on Europa
I am Tengbao, a popular science creator who loves astronomy. I also hope that everyone will pay more attention and support
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