The interstellar visitor 3I-ATLAS surprised us: What did it reveal to us with its light beyond the Sun?

Have you heard about comet 3I-ATLAS? It may not sound like an exciting topic until you find out that it is one of the rare visitors from outside our Solar System – a comet from interstellar space! And just recently, it caused a surprise by suddenly shining much brighter when it briefly disappeared behind the Sun. Sounds like science fiction? It’s not! In this post, you will learn what this means and why it is important – without complicated scientific jargon.

What is comet 3I-ATLAS and why is it special?

Most of the comets we see in the sky belong to our Solar System. However, 3I-ATLAS is not one of them. It is a comet that comes from among the stars – literally! That’s why it is called an interstellar comet. This means it is not connected to our Sun but comes from another place in the universe and is just passing through our part of the galaxy.

Before it, we only knew of two similar cases – the famous ʻOumuamua and 2I/Borisov. Comet 3I-ATLAS is therefore the third known visitor from a foreign star system. These are rare opportunities that allow astronomers to gain insight into what material exists elsewhere in the galaxy.

How was it discovered and how was it observed?

The comet was first observed in December 2022, and the spacecraft SOHO (Solar and Heliospheric Observatory) closely monitored it. But for a short time, it was hidden behind the Sun. And that’s when something interesting happened.

When it reappeared from behind the Sun in early 2024, it suddenly shone brightly – its brightness increased tenfold! What happened to it behind the Sun that made it shine so brightly? That’s what piqued scientists’ interest.

The illumination that surprised experts

What does it mean that it shone? Well, comets are actually icy ‘clumps’ of gas, dust, and rock. As they approach the Sun, the icy materials vaporize, causing the comet to glow and create the famous tail. But the brightness of 3I-ATLAS increased unusually quickly and strongly.

The space telescopes ESA/NASA Solar Orbiter and STEREO-A were fortunate enough to be in an ideal position for observation. The results astonished scientists – the brightness of the comet increased at a time when they expected it to weaken due to its proximity to the Sun. It’s as if it disappeared on the sunny side and returned… full of energy!

What could have caused this increase in brightness?

• Melting ice: One theory suggests that fresh, still-unheated parts of the comet were revealed during its jump over the Sun – like peeling the skin off an ice clump to reach the cold core.
• Trapped gases: Comets often contain trapped gases that can explode when exposed to the Sun. It’s like a drink bottle starting to fizz if left in the sun.
• Core breakup: There is a possibility that the comet broke apart or partially fractured, which would have caused a sudden increase in the amount of shining material.

Regardless of the reason, the event gave scientists a unique opportunity to study how interstellar objects behave in our conditions. And we don’t get that very often.

What can we learn from the visit of comet 3I-ATLAS?

With each such visit, we get a “sample” of the material composition that formed outside our star system. It’s like opening a piece of another galaxy and peeking inside. Is the composition similar to our comets? Does it contain substances we don’t even know about yet?

Although it was not possible to obtain direct samples, the data on the brightness and behavior of the comet is valuable information. And tools like SOHO and Solar Orbiter allow us not only to see such phenomena but also to study them scientifically.

Why is this important for all of us?

You might be wondering: “Why should I even care about an interstellar comet?”

Good question! Let us give you an analogy. Imagine you’ve eaten only locally grown fruit in your city your whole life. Suddenly, someone brings you a fruit from another continent. What does it smell like? How does it taste? How is it different from your usual fruit? It’s similar with comets – although we have “local” ones, those from other parts of the galaxy can be completely different.

Such events expand the boundaries of our understanding of the universe. They increase our curiosity and encourage us to ask: What else is out there?

And what’s next?

Currently, scientists are busy analyzing the data sent by a fleet of space observers. Collaborations between NASA and ESA (European Space Agency) allow this data to be compared with the behavior of other comets – both local and interstellar.

And in the meantime, we can know that we have witnessed something rare and extraordinary. And who knows – perhaps the next interstellar visitor will be even more surprising.

Stay curious

The universe is a very special place, full of mysteries and wonders. Every time we look up at the stars, there is a chance we might discover something entirely new. Comet 3I-ATLAS has shown us that even objects from distant corners of the galaxy can shine in full light – if only we give them a chance.

If you are interested in interstellar objects, comets or just want to admire the beauty of the universe, keep following us. Every day, something magical happens out there – we just need to look up at the sky.

Did you find this comet interesting?

Have you ever observed a comet in the sky? Do you have a question about their formation or journey? Write it in the comments! Who knows, maybe your question will inspire the next post.

Keywords: interstellar comet, 3I-ATLAS, comets, universe, Sun, NASA, Solar Orbiter, SOHO, Comet brightness, comet tail, interplanetary space, Oumuamua, celestial bodies