Unlocking the Mystery: Astronomers Discover the Origin of Our First Interstellar Comet!

There’s exciting news in our Solar System! Astronomers have spotted a new interstellar object named Comet 3I/ATLAS. This isn’t just any comet; it comes from the thick disk of our Milky Way, which makes its story unique compared to previous visitors.

Matthew Hopkins, an astrophysicist from the University of Oxford, led a team that quickly figured out 3I/ATLAS’s origins just days after its discovery. Their findings were shared in The Astrophysical Journal Letters and are available here.

The Solar System is full of rocks and comets, mostly formed from material leftover from the Sun’s birth. These objects can take many paths around the Sun. Some have long orbits that last millions of years, while others stay closer, within Venus’s orbit.

3I/ATLAS is the third object identified as coming from outside our Solar System, following two others, ‘Oumuamua in 2017 and comet 2I/Borisov in 2019. It is a thrilling reminder of the vastness of the universe.

Discovered on July 1, 2025, 3I/ATLAS was racing through space at about 57 kilometers per second (or roughly 35 miles per second). It will make its closest approach to the Sun inside Mars’s orbit in October 2025, before continuing its journey back into interstellar space. Scientists estimate it to be around 10 to 20 kilometers wide, with a blue surface and a reddish coma, differing from other comets typically found in our Solar System.

Hopkins and his team used the Ōtautahi-Oxford interstellar object model to trace back the comet’s origins in the Milky Way. This model combines data from Gaia, a space telescope, with models of how objects move and interact in our galaxy. The thick disk of the Milky Way is home to older stars, many over 10 billion years old, making it quite different from the region where the Sun resides.

If this origin is confirmed, it suggests that 3I/ATLAS is much older than our Solar System, estimated to be between 7.6 to 14 billion years old. In contrast, the Sun is about 4.6 billion years old. This points to the possibility that not all known interstellar visitors come from the same region, highlighting the diversity of these celestial objects.

Interestingly, the thick disk contains only about 10 to 15 percent of the Milky Way’s stars. This means that objects like 3I/ATLAS are rare and provide valuable insights into planet formation and evolution from varied galactic environments.

As scientists continue to study interstellar objects, they might gain better understanding of cosmic phenomena. Each new discovery can help refine existing models and encourage exploration beyond our Solar System.

For more detailed research findings, you can read the full paper here. Let’s keep an eye on 3I/ATLAS as it travels through our cosmic neighborhood!

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