Interstellar comet 3I/Atlas: Threat to Earth, speed, age and other questions answered

Interstellar comet 3I/Atlas is the hottest topic among astronomers right now. Its speed, light, trajectory, tail, everything is strange. This visitor from outside the solar system is not behaving like a typical comet. Its appearance and behaviour have confused scientists. One of them has even flagged it, claiming it could be a dangerous alien spaceship coming to probe the planets in the solar system, and that we should be ready to combat a possible threat. This has made even the common man interested in the comet. The alien attack theory has gone viral, and everyone is looking for answers. Here are some common questions answered about 3I/Atlas.

What is 3I/Atlas?

It is an interstellar object that was first observed on July 1 by the ATLAS Survey Telescope in Chile. Since then, several other telescopes, such as the James Webb, Hubble and the Very Large Telescope, have also captured images of the object zooming through the solar system.

Also Read: 3I/Atlas anomalies: Its mass is likely bigger than 33 billion tons, too large to be a comet

How do we know that 3I/Atlas is coming from interstellar space?

3I/Atlas has a strange trajectory. Its path is careening through the solar system in a way that comets that reside in our solar system do not typically behave. This led scientists to conclude that 3I/Atlas is an interstellar visitor.

Speed of 3I/Atlas

The object is moving at a staggering speed of 221,000 km/hr.

Also Read: Interstellar object 3I/ATLAS grows visible tail in live Gemini images. So, it's a comet?

How old is 3I/Atlas?

The alien comet is older than our solar system. According to a July 2025 study led by Matthew Hopkins, 3I/ATLAS could be between 7.6 and 14 billion years old. This makes 3I/ATLAS older than the solar system, which was born 4.6 billion years ago.

How big is 3I/Atlas?

There is no consensus on the size of 3I/Atlas. The Hubble Space Telescope observations suggest that the diameter of 3I/ATLAS's nucleus is between 0.32 and 5.6 km, with scientists saying it is likely only about a kilometre in diameter. Meanwhile, Harvard scientist Avi Loeb claims that its nucleus measures 46 kilometres. Recently, a study by Loeb, Richard Cloete and Peter Veres showed that the mass of 3I/ATLAS must be bigger than 33 billion tons, and that the "diameter of its solid-density nucleus must be larger than 5 kilometres."

When was 3I/Atlas first seen?

Officially, it was first detected on July 1 by the Atlas telescope in Chile. However, scientists then checked for more data on other telescopes and found that NASA's Transiting Exoplanet Survey Satellite (TESS) had pictured it back in May. It showed that between May 7 and June 3, 3I/ATLAS suddenly became five times brighter. This increasing brightness was an anomaly, as scientists say the brightness should have gone up by only 1.5 times.

3I/Atlas anomalies

If it is 33 billion tons in mass, it is an anomaly for a regular comet. Its trajectory makes it pass through most of the planets in the solar system, which has also been flagged as an anomaly. It also lacked a cometary tail for a long time, which stumped scientists. It is moving at an extremely fast speed. Loeb even claimed at one point that it seems to be generating its own light.

Will 3I/Atlas hit Earth?

No. The interstellar object is slated to safely pass by Earth. Its closest approach to our planet will be in December 2025, when it will be at a distance of about 1.8 AU (273 million kilometres).

Where is 3I/Atlas now?

Right now, 3I/Atlas is about 3.5 astronomical units (523 million kilometres) from Earth. It is zooming towards the inner solar system and is inside the orbit of Jupiter. It will reach perihelion, that is, its closest point to the Sun, on October 30, 2025.