An interstellar comet that originated outside our solar system has just passed its closest approach to the Sun, putting it on an outward path—but it hasn't yet left our cosmic neighbor.
The comet, known as 3I/ATLAS, was around According to EarthSky, it is 126 million miles (203 million kilometers) from our star. From the perspective of ground-based telescopes on Earth, the object is currently behind the sun, but astronomers expect to be able to observe the comet again in a few weeks, said Daryl Seligman, assistant professor in the Department of Physics and Astronomy at Michigan State University.
Starting on November 11, stargazers using telescopes should be able to see the object in the predawn sky, according to EarthSky.
Astronomers still have months to observe the comet before it starts moving Leave our solar system, Seligman said.
The comet will make its closest approach to Earth on December 19, at a distance of about 168 million miles (270 million kilometers), but it does not pose a threat to our planet, according to the European Space Agency.
Astronomers have been observing the comet, the third known interstellar object to pass through the solar system, since its discovery on July 1.
Each observation is revealing this interstellar object and how different it is from comets that originate in our solar system.
Comets are like dirty snowballs left over from the formation of the solar system.
The comet's nucleus is its solid core, made of ice, dust, and rock. When comets approach stars like the sun, heat causes them to release gas and dust, forming their signature tails.
Astronomers are interested in capturing as many observations of the comet as possible because the material released from the object as it approaches the Sun can reveal more about its composition and the star system from which it originated.
“When it's closest to the sun, you get the most comprehensive view of the nucleus,” Seligman said. “One of the main factors that drives most comet scientists is, what is the composition of the volatiles? It shows you the original raw material from which it was formed.”
Scientists use powerful tools like the Hubble Space Telescope and the James Webb Space Telescope, as well as numerous space-based missions such as SPHEREx, to study the comet.
According to ESA, SPHEREx and Webb observations found that comets release carbon dioxide, water, carbon monoxide, carbonyl sulfide and water ice as they approach the sun.
Preliminary estimates indicate that there are 3 billion interstellar comets Up to 11 billion years old, according to an August study co-authored by Seligman and Aster Taylor, a doctoral student at the University of Michigan and a researcher at Fannie Mae and the John F. Hertz Foundation. For reference, our solar system is estimated to be about 4.6 billion years old.
Carbon dioxide changes directly from solid to gas more easily than most elements in response to changes in temperature, Seligman said, meaning the comet likely never got close to another star before its pass by the sun.
The interstellar comet disappeared from the view of ground-based telescopes in October, but it remains in view by missions such as PUNCH (Politometer to Unify the Corona and Heliosphere) and SOHO (Solar and Heliospheric Observatory). The object also made its closest approach to Mars on October 3, coming within 18.6 million miles (30 million kilometers) of the red planet and the spacecraft orbiting it.
Although the government shutdown has prevented any of NASA's missions observing the comet since October 1 from sharing data, the European Space Agency's Mars Express and ExoMars Trace Gas Orbiter attempted to capture images of 3I/ATLAS in October.
The cameras on these missions are designed to study the relatively nearby, bright surface of Mars, but the ExoMars Trace Gas Orbiter successfully observed the comet as a fuzzy white dot.
“This was a very challenging observation for the instrument,” Nick Thomas, principal investigator for the orbiter's camera, said in a statement, noting that the comet was “about 10,000 to 100,000 times dimmer than our usual targets.”
ESA's Jupiter Icy Moons Explorer will also attempt to observe 3I/ATLAS in November using a variety of instruments, although the comet will be farther away from the spacecraft than it was when observed. Mars Orbiter. But because of the speed at which the spacecraft sends data back to Earth, astronomers don't expect to receive the observations until February.
“We still have a few months to see it,” Seligman said. “And there’s going to be amazing science.”
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