Now you see it, now you don’t.
The Mars Express A spacecraft has seen a rare sight, a discovery Mars‘ the moon Demos He seems to be walking in the past Jupiter And his moons on Valentine’s Day (February 14). The event is called . hideIt allows scientists to more accurately calculate Deimos’ orbit around the Red Planet, a surprisingly difficult task.
In astronomy, magic occurs when a celestial body moves in front of another, blocking the farthest object from view. In the newly released video, which includes 80 images taken by the Mars Express spacecraft’s high-resolution stereo camera, Deimos first goes over the bright spots that are oceanic moons. Europe And Ganymede. Then it passes in front of the white disk of Jupiter, and finally two other great Jovian moons, volcanic io and freezing Callisto.
Related: Moons of Mars: Amazing Pictures of Phobos and Deimos
At the time, Jupiter’s system was about 463 million miles (745 million km) from Deimos, which is about 7.7 miles (12.4 km).
A few weeks later, on March 30, the second moon of Mars, PhobosShe passed in front of Deimos who had watched the Mars Express.
For scientists who study the moons of Mars, all of these disappearance events are important in more accurately determining the orbits of Deimos and Phobos. Perhaps surprisingly, astronomers do not know the exact shape and size of the orbits of Phobos and Deimos. But scientists know that gravitational forces between the moons and Mars change the moons’ orbits.
Phobos, which is 14 miles (22.5 km) wide, orbits 3,721 miles (5,989 kilometers) above the red planet — close enough that it’s moving around Mars faster than Mars. Ultrafast orbit causes tidal bulges on Mars due to Phobos’ gravitational lag behind the Moon. Then the bulge’s gravity pulls back into Phobos, causing Phobos to gradually decelerate and slowly approach Mars. In 50 million years, Phobos will be very close to Mars and the tidal forces will be so strong that Phobos will disintegrate, with debris falling onto Mars or forming a ring.
On the other hand, Deimos has a wider orbit of 14,580 miles (23,460 km), which makes the orbital period slower than that of Mars. This means that the tidal bulge on Mars caused by Deimos’ gravity has drifted away in front of Deimos, causing the Moon’s orbital velocity to accelerate while the bulge’s gravity pulls on Deimos. Therefore, its orbit expands over time. Earth’s moon It is slowly moving away from our planet due to the same type of interaction.
Although scientists understand the factors that change the orbits of Phobos and Deimos, efforts to accurately measure the orbits of the two moons have run into difficulties. Moons often get lost in the glare of Mars when viewed from Earth, so we must rely on spacecraft from the Red Planet to make the measurements. One way to do this is to determine the duration of the occlusion. The time it took Deimos to darken on Jupiter tells scientists exactly how far the Moon is from Mars.
The European Space Agency’s Mars Express mission observed the unseen solar system objects from Mars’ moons over the past 14 years, using these events to constrain the orbits of Phobos and Deimos, and improving our orbital measurements by 1.6 to 2 miles (1 to 2 km).
The unseen views also show how distorted the two moons are; One theory is that they were caught nearby asteroid beltWhile the other is that they are parts of a larger moon was break through impact 2.7 billion years ago.
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