The picture that began all of it… This picture reveals the second interstellar comet 3I/ATLAS was found

When we glance again on 2025 from an astronomical perspective, comet 3I/ATLAS is bound to be thought of one of many highlights of the 12 months.

This interstellar customer from past our Solar System has captured our consideration – and, in some circumstances, our wild imaginations – because it was first found again in June 2025.

It’s an interstellar comet, which means that, not like the overwhelming majority of comets we all know of, which originated from inside our Solar System, 3I/ATLAS originated from elsewhere within the galaxy.

As a outcome, studying extra about 3I/ATLAS can train astronomers about what different star programs are like, and the way interstellar spacerocks examine to these discovered inside our personal cosmic neighbourhood.

James Webb Space Telescope observations, for instance have discovered water ice, water vapour, carbon monoxide and carbonyl sulfide at 3I/ATLAS.

In reality, thus far, observations recommend the mud and ice discovered at 3I/ATLAS is just like these discovered at comets that fashioned inside our Solar System.

3I/ATLAS discovery

Let’s take ourselves again to the beginning of summer time 2025, when this unbelievable interstellar comet was found.

It was discovered by the ATLAS (Asteroid Terrestrial-impact Last Alert System), which is a venture developed by the University of Hawaii and funded by NASA.

ATLAS is an early warning system, designed to detect doubtlessly harmful asteroids and provides humanity a heads-up about any that look to be coming our manner.

The complete setup is automated and consists of 4 telescopes in complete: two in Hawaii, one in Chile and one in South Africa.

These telescopes are fitted with cameras that mechanically scan and {photograph} the entire sky a number of occasions an evening.

The system takes 4 pictures of every a part of the sky, at intervals separated by 12 minutes.

It then seems to be for objects transferring rapidly towards the background sky by evaluating the pictures and recognizing variations between them.

Stars, for instance, will probably be in the identical place from one picture to a different.

But one thing a lot nearer and transferring quick, like a comet or asteroid, may have modified place considerably when a number of pictures of the identical patch of sky are in contrast.

The laptop system detects objects which have moved or which have altered in brightness, and picks out potential asteroids and comets from different transient objects like variable stars or supernovae, for instance.

This approach is a well-established astronomical methodology for locating new objects, often called ‘blinking’.

Pluto, for instance, was found utilizing the ‘blinking’ methodology, by evaluating pictures of the identical patch of sky and recognizing an object transferring rapidly, relative to the background stars.

Of course, again in 1930 when Pluto was found, the blinking was carried out manually by astronomer Clyde Tombaugh, however these days laptop programs do the blinking work mechanically.

Comet 3I/ATLAS was found utilizing this method, as the pictures above present.

The animation you’ll be able to see additional up this web page is fabricated from a sequence of frames captured by the ATLAS system, clearly exhibiting an object transferring throughout the sky.

It was, in actual fact, the ATLAS survey telescope in Chile that first reported that the comet comes from interstellar house.

And since its discovery, a few of Earth’s strongest telescopes have been pointed at 3I/ATLAS, together with the Very Large Telescope, the Hubble Space Telescope and the James Webb Space Telescope.

As the comet approaches the Sun, Earth and Mars this autumn, there’s even discuss of different spacecraft like Mars rovers and orbiters, or the NASA Juno mission at Jupiter, catching a glimpse.

3I/ATLAS will not go into orbit across the Sun: it is merely passing via our Solar System on its journey throughout the Galaxy.

But one factor’s for certain, astronomers are doing every part they will to be taught as a lot as they will about this unusual, mysterious customer, whereas it occurs to be within the neighbourhood.

Future sky surveys like these carried out by the Vera Rubin Telescope, which has simply begun science observations, could open up many extra of those interstellar objects for commentary.

We could possibly be on the point of a brand new period in our understanding of primordial spacerocks from the depths of the cosmos.