The rotation speed of one of the objects near the earth is increasing

Asteroid Phaeton, classified as a potentially dangerous near-Earth object, is spinning faster and faster every year, but scientists still don't know exactly why.

BingMag.com The rotation speed of one of the objects near the earth is increasing

Asteroid Phaeton, classified as a potentially dangerous near-Earth object, is spinning faster and faster every year, but scientists still don't know exactly why.

This space rock named "3200 Phaethon" is about 5.4 km wide and it comes closer to the Sun than any other asteroid in the solar system until it reaches a minimum distance of about 20.9 million. Kilometers from the Sun means less than half the distance of Mercury.

In this 524-day elliptical orbit, Phaeton is close enough to the Earth to be classified as a "potentially dangerous" object. But it is still very far from Earth, and the closest recorded distance to it was in 2017, when it passed within 10.3 million kilometers of our planet, or about 27 times farther than the Moon.

This asteroid is for another reason. It is also famous. Its dusty trail causes the "Geminids" meteor shower, which reaches its peak in early December (mid-December) every year and can be seen all over the world.

Now, according to the results presented at the conference American Astronomical Society Planetary Sciences October 7 (25 Mehr), Phaeton's rotation is accelerating. It takes about 3.6 hours to complete one revolution, but this time shortens by about 4 milliseconds every year. This number may not seem like much, but over thousands or millions of years it can change the asteroid's orbit.

BingMag.com The rotation speed of one of the objects near the earth is increasing

Path of Phaethon in 2017
Credit: Tom Ruen/Wikimedia

Astronomers first identified Phaethon as asteroid 3200 in 1983 and The asteroid's orbit has been tracked so far by light curves that show the brightness of an object and thus its rotation and motion over time, as well as by radio telescopes and the occasional disappearance of stars behind it. Therefore, this object has one of the most well-known orbits among the asteroids in the Solar System.

Using a multi-decade data set, the research team simulated Phaeton's shape and rotation characteristics in greater detail than before and found that This near-Earth asteroid is raised around its equator like a rotating gyre.

This shape is among the large asteroids such as "162173 Riogo" (162173 Riogo), which in 2018 the Japanese spacecraft in an innovative operation of It sampled, it's common, but there was something weirder about Phaeton's spin analysis.

BingMag.com The rotation speed of one of the objects near the earth is increasing

Orbit of asteroid Phaeton
Credit: NASA/JPL

"Sean Marshall" (Sean Marshall), the senior researcher of this study and an astronomer at the Arecibo Observatory of the National Science Foundation of America said in this regard. : "The modeling predictions of the asteroid's shape did not match the observational data, and the peak times of the model did not clearly match the peak times of Phaeton."

After reanalyzing the data, the scientists concluded They concluded that the only explanation is that Phaeton's rotation speed is increasing year by year.

An asteroid's rotation is very unusual, and out of more than 1.1 million known asteroids, Phaeton is the 11th asteroid with a rotation. Hastedar has been observed. This asteroid is also unusual in other ways. First, its comet-like tail is composed of pieces of rock detached from its surface, creating the spectacular Geminid meteor shower. Second, the light reflected from the Sun by it has a bluish color, which, like most comets, is almost never seen among asteroids. For this reason, astronomers have often nicknamed Phaethon the "rock comet". caption-text">Asteroid Phaeton in a spin
Credit: Taylor et al. 2019, Planetary and Space Science 167

The reason for Phaeton's accelerated rotation is still not clear. Its trail-like tail means that its mass is gradually decreasing, but this does not necessarily justify the change in rotation speed. Researchers also believe that the asteroid's unusual tail is the result of its surface heating up near the Sun.

So the most likely explanation is that the asteroid's surface is affected by solar radiation and changes its rotation. A phenomenon known as the Yarkovsky-O'Keefe-Radzievskii-Paddack effect, but it is difficult to prove about Phaeton with the available data.

Due to its unusual properties Phaeton, the Japan Aerospace Exploration Agency (JAXA) has chosen it as the target of one of its next asteroid missions, and in 2024 the "Destiny+" probe will be sent into space to finally reach Phaeton in 2028. "This is good news for the DESTINY+ team," said Marshall. A fixed change to this It means that the orientation of the Phaeton during the flight of the spacecraft can be accurately predicted. For example, scientists can determine which side of the asteroid will be illuminated by the sun when the spacecraft arrives, and which areas they should target for their studies. Credit: IPAC/JPL-Caltech/NASA

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