New findings about comet 3I/ATLAS reveal it has likely shed a lot of mass after its close flyby of the Sun. This interstellar visitor was first spotted on July 1, 2021, by astronomers at the Asteroid Terrestrial-impact Last Alert System (ATLAS). It’s on an escape path out of our Solar System, just like 1I/ʻOumuamua and 2I/Borisov, making it the third known interstellar object.
Despite various conspiracy theories online, many telescopes continue to track 3I/ATLAS and share their observations. You can find a wealth of data on the Minor Planet Center website. This comet is like a time capsule from the early universe, offering insights into the interstellar medium. Though it isn’t an alien spacecraft, its characteristics are fascinating.
During its close approach to the Sun, known as perihelion, the comet was briefly hidden from view but was imaged by the European Space Agency’s Mars Express and ExoMars Trace Gas Orbiter. Now that it’s back in our line of sight, astronomers are eager to study the effects of solar radiation on it. So far, they’ve seen some unusual behavior, like a rare anti-tail and unexpected ratios of iron and nickel. These traits hint that 3I/ATLAS behaves differently than comets typically found in our Solar System.
Recent observations from late October show that the comet has indeed lost a notable amount of mass during its perihelion. According to Avi Loeb, an astrophysicist from Harvard, the data indicate that 3I/ATLAS has experienced a unique acceleration. This isn’t unusual for comets since they lose mass as ices vaporize when heated by the Sun.
Loeb’s analysis suggests that the mass loss amounts to around 13%, depending on the speed of outgassing. It’s important to remember that such mass loss is common among comets. As this third interstellar object has peculiar features, further observations will help clarify how it behaves after interacting with solar radiation.
If it has really lost this mass, scientists expect to see a cloud of gas and increased brightness in future observations. In fact, recent data shows that the comet has already brightened significantly, indicating it remains active and continues to provide valuable insights about another region of our galaxy.
This research highlights how even the slightest changes in celestial bodies can reveal much about their origins and behaviors. As we keep observing 3I/ATLAS, we might learn more about the cosmos and our own Solar System’s history.
