Asteroid behaves strangely - researchers are puzzling what is behind it

The asteroid (6478) Gault has long been known to researchers. However, he has been behaving strangely for some time now - and has puzzled scientists.

• The asteroid (6478) Gault was discovered in 1988 and is actually unusual
• Now the asteroid is causing a sensation with two phenomena
• Even the “Hubble” space telescope focuses on the asteroid

The asteroid (6478) Gault is actually an old acquaintance. Discovered by Carolyn and Eugene Shoemaker in 1988, it has long been known that it takes three and a half years to orbit the sun and has a diameter of around 3.7 kilometers. But the asteroid has been surprising researchers for some time.

Asteroid (6478) Gault is an active asteroid - and behaves strangely

In spring, scientists discovered that the asteroid (6478) Gault is an active asteroid: it emits dust and not only pulls a tail behind it, but two at the same time. This is unusual and actually the behavior of a comet rather than that of an asteroid . While the astronomers are still wondering why the asteroid is pulling the dust trails behind them, a team of scientists publishes a report in the journal "Astrophysical Journal Letters", which describes another unusual behavior of the asteroid.

Researchers had observed Asteroid (6478) Gault because of its two tails

The MIT scientists led by Michael Marsset had actually observed the asteroid to find out more about its two unusual tails. "We know a million celestial bodies between Mars and Jupiter and maybe 20 are active in the asteroid belt," Marsset is quoted in a MIT statement. "So that's very rare." For two nights, the scientists targeted the asteroid with a telescope in Hawaii - and were able to observe something fascinating: the asteroid changed color while the astronomers were watching it.

The reddish asteroid became a blue colored asteroid in infrared light. "It was a very big surprise," says Marsset. "We have never seen a change as dramatic as this in such a short time," says co-author Francesca DeMeo. The scientists believe that the dust on the surface of the asteroid has been colored red by sunlight for millions of years. The asteroid may have lost this layer of dust due to its rapid rotation around its own axis. "We can now see the underlying surface of the asteroid, fresh, blue layers," says Marsset.

Rotation of Asteroid (6478) Gault may have caused the color change

According to the researchers, the rotation of the asteroid could have been triggered by the YORP effect (named after the researchers Yarkovsky, O'Keefe, Radzievskii and Paddack). The YORP effect is the influence of the sun on smaller celestial bodies: asteroids reflect a large part of the solar radiation, but a part of it is absorbed and released again as heat and thrust. In this way, an asteroid can spin rapidly over millions of years - in the end, the asteroid could even disintegrate.

The researchers now want to continue to observe the asteroid with the strange behavior. Because even the thing with the two tails is far from clear. “It is the first time, as far as I know, that we see a stone celestial body emitting dust, much like a comet,” says Marsset.

"Hubble" photographed Asteroid (6478) Gault with two tails

The Hubble space telescope also photographed the asteroid with the two tails. Astronomers estimate that the longer tail extends about 800,000 kilometers into space, while the second tail is about a quarter as long. Astronomers conclude that there are several million kilograms of dust in the two tails. How the asteroid ejects the dust is unclear. Like most other asteroids, it mainly consists of silicate, a dry, stony material.

Comets, on the other hand, come from the cold depths of the solar system. As they approach the sun, the ice melts on their surface and becomes a gas that, together with dust particles, forms the characteristic tail of a comet.

The "Hubble" space telescope was also involved in an astronomical sensation: Using the "Hubble" data, researchers discovered water vapor in the atmosphere of the exoplanet K2-18b. In addition, Komet C / 2019 Q4 * is currently observing a celestial body that may originate from outside the solar system. Is it the second interstellar visitor to our solar system?

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By Tanja Banner

* fr.de is part of the nationwide Ippen-Digital central editorial office.