Comet 3I/ATLAS passes by Earth tonight! When is the best time to view Interstellar comet 3I/ATLAS? Will be closest to our planet at..

According to NASA, 3I/ATLAS has an icy nucleus and a coma, which is a bright cloud of gas and dust that surrounds the comet and is emitted at increasing rates as the comet approaches the Sun.

The interstellar comet known as 3I/ATLAS will reach its closest point to Earth early morning on Friday, December 19. However, it will not come close enough to pose any threat to our planet. Nonetheless, astronomers have determined the exact date and time when 3I/ATLAS will be in a position closest to Earth so that those interested can experience this view to the fullest. Visibility will depend upon local weather conditions as well as whether it is day or evening at the precise moment that you’re looking at 3I/ATLAS. Comet 3I/ATLAS is only the third known object to pass through our solar system from outside it.

When will comet 3I/ATLAS make its closest approach to Earth?

Comet 3I/ATLAS will come closest to Earth on December 19 at 1:00 a.m. EST (11:00 a.m. Indian Standard Time), according to orbital calculations made by NASA’s Jet Propulsion Laboratory (JPL) Horizons system. At that time, the comet will be roughly 1.8 astronomical units away, or roughly 168 million miles (270 million kilometers), or roughly twice the average distance between Earth and the Sun.

“At its closest, the comet will still be very far away from our planet, at nearly twice the distance of the Sun: On Dec. 19, 2025, 3I/ATLAS will be about 1.8 astronomical units (about 170 million miles, or 270 million kilometers) from Earth,” NASA, in a frequently asked questions segment, said.

NASA-funded ATLAS survey telescope discovered comet 3I/ATLAS on July 1, 2025, in Rio Hurtado, Chile. It is the third known interstellar object to orbit the Sun, after Oumuamua and 2I/Borisov. Although 3I/ATLAS will be too distant and faint to be seen with the naked eye as it passes near Earth, its flyby is scientifically valuable, as interstellar objects are extremely rare.

What is comet 3I/ATLAS and why is it called interstellar?

According to NASA, 3I/ATLAS has an icy nucleus and a coma, which is a bright cloud of gas and dust that surrounds the comet and is emitted at increasing rates as the comet approaches the Sun.

3I/ATLAS is on what’s called a hyperbolic trajectory, which means it is moving too fast to be bound by the Sun’s gravity and, therefore, is not following a closed orbital path around the Sun. It is simply passing through our solar system.

Astronomers don’t yet know exactly how big 3I/ATLAS is, but from Hubble Space Telescope observations as of Aug. 20, 2025, they can see that the diameter of its nucleus is not less than 1,400 feet (440 meters) and not greater than 3.5 miles (5.6 kilometers).