Comet 3I/ATLAS, the third known and fastest interstellar object to fly across our Solar System, has been spotted spewing a large amount of dust as it approaches the Sun. The comet’s tail is typically weak, but its latest behavior is unusual – the dust is not being released behind the comet, instead flowing in the direction of the Sun.
Comets are composed of frozen gas, rock, and dust, earning them the nickname “dirty snowballs.” As they draw closer to the Sun, their surface begins to sublimate, creating a coma and a fuzzy atmosphere. However, Comet 3I/ATLAS’s unique behavior is more likely due to its true nature rather than any unusual solar wind effects.
Researchers using the Hubble telescope have observed that the comet experiences intense dusty sublimation on the Sun-facing side but not on the night side. This creates a distinct release of debris on the sunny side. There are two possible explanations for this phenomenon: the comet may be spinning with its polar axis pointing towards the Sun, causing the night side to remain dark, or its surface has been heavily weathered due to cosmic rays, reducing its ability to form long tails.
Discovered in 2020 by NASA’s Asteroid Terrestrial-impact Last Alert System (ATLAS), Comet 3I/ATLAS is a rare and fascinating object. It is the third interstellar visitor to our Solar System, with the previous two being ‘Oumuamua and Comet 2I/Borisov. This comet is twice as fast as the previous two, reaching speeds of up to 35 miles per second.
Comet 3I/ATLAS will come within 130 million miles of the Sun on October 30, 2025, a distance farther than Earth’s orbit. The comet will be visible from Earth until September and then disappear behind the Sun until December, when it returns for another viewing.
Source: https://www.iflscience.com/interstellar-comet-3iatlas-looks-back-to-front-with-dust-shooting-toward-the-sun-80513