An interstellar comet known as 3I/ATLAS has recently completed its closest encounter with the sun, which has placed it on a trajectory that will eventually lead it out of our solar system. However, it is not departing immediately, as astronomers are still able to study it closely.
According to EarthSky, the comet approached within approximately 126 million miles (203 million kilometers) of the sun. Currently, from the viewpoint of telescopes on Earth, the comet is situated behind the sun. Nonetheless, astronomers expect to resume observations in the coming weeks. Darryl Seligman, an assistant professor in the physics and astronomy department at Michigan State University, indicated that stargazers equipped with telescopes will have the opportunity to view the comet in the early morning sky starting November 11.
As 3I/ATLAS continues its journey, it will make its closest pass to Earth on December 19, coming within about 168 million miles (270 million kilometers). The European Space Agency has confirmed that this comet poses no danger to our planet.
This comet is significant as it is only the third known interstellar object to traverse our solar system, having been detected since its discovery on July 1. Each observation contributes valuable insights into the nature of this interstellar visitor and how it differs from comets that were formed within our solar system.
Comets are often described as “dirty snowballs,” remnants from the formation of planetary systems. They consist of a solid core made of ice, dust, and rock. As comets approach stars like the sun, the heat causes them to emit gas and dust, forming their characteristic tails. Astronomers are eager to gather as much data as possible from the comet, especially as it nears the sun, as the material released could provide clues about its composition and the star system from which it originated.
Seligman noted, “When it gets closest to the sun, you get the most holistic view of the nucleus possible.” He emphasized that understanding the composition of the volatiles is crucial, as it reveals the primordial materials from which the comet formed.
Advanced instruments, including the Hubble Space Telescope and the James Webb Space Telescope, alongside various space missions like SPHEREx, are being utilized to analyze the comet. Observations from these missions have identified several substances, including carbon dioxide, water, carbon monoxide, carbonyl sulfide, and water ice, being released by the comet as it approaches the sun.
Initial studies suggest that the comet is between 3 billion and 11 billion years old, as reported in a research paper co-authored by Seligman and Aster Taylor, a doctoral student at the University of Michigan. This age is particularly intriguing when considering that our solar system is estimated to be around 4.6 billion years old. Seligman explained that carbon dioxide transitions from solid to gas more readily than many other elements, implying that this comet has likely never been near another star before its recent encounter with the sun.
Although the comet became too faint for ground-based telescopes to track in October, it remained observable by missions such as PUNCH (Polarimeter to Unify the Corona and Heliosphere) and SOHO (Solar and Heliospheric Observatory). Notably, it passed closest to Mars on October 3, coming within 18.6 million miles (30 million kilometers) of the planet. Despite a government shutdown that limited data sharing from NASA missions since October 1, the European Space Agency”s Mars Express and ExoMars Trace Gas Orbiter made attempts to capture images of 3I/ATLAS, with the latter managing to view the comet as a faint dot.
Looking ahead, the ESA”s Jupiter Icy Moons Explorer (Juice) will also try to observe 3I/ATLAS in November using various instruments, despite the increased distance from the comet compared to previous observations. However, researchers anticipate that data from these observations may not be available until February due to the data transmission rates of the spacecraft.
Seligman concluded, “We”ve got several more months to observe it. And there”s going to be amazing science that comes out.”
