Are the Butterfly Galaxies Our Future Sky?

Image: Composite optical image of the Butterfly Galaxies taken with ESO’s Very Large Telescope in Chile. It was created using broadband filters centred at 440 nm (B-band, blue), 557 nm (V-band, green), and 655 nm (R-band, orange), together with a narrow-band filter, focused on the emission of ionised hydrogen (Hα, red). NGC 4567 is the smaller galaxy that we see nearly face-on, while its much larger companion is NGC 4568.  Image Credit: ESO

Have you ever looked at an image of two colliding galaxies and wondered, “Is this what will happen to us one day?”

Welcome, dear reader, to FreeAstroScience, where we turn big cosmic questions into stories you can actually enjoy and share with friends. This article was crafted by FreeAstroScience.com only for you, with one simple goal: to help you understand what is really going on in the Butterfly Galaxies and what their slow-motion crash can teach us about the future of the Milky Way.

So grab a drink, stay with us until the end, and keep your mind awake—remember, “the sleep of reason breeds monsters.”

What exactly are the Butterfly Galaxies?

Where are they and how far away?

The Butterfly Galaxies are a pair of spiral galaxies catalogued as NGC 4567 and NGC 4568, floating about 60 million light‑years away in the constellation Virgo. Astronomers also list them under other names—PGC 42064/42069, UGC 7776/7777, and the interacting system VV 219—so yes, they have more aliases than a comic‑book villain. They belong to the Virgo Cluster, a huge gathering of thousands of galaxies that dominates our corner of the universe and strongly shapes how its members move and evolve.

From Earth, the pair covers only a few arcminutes on the sky, so you need a decent telescope or a long‑exposure camera to see their full shape. Modern images from ESO’s Very Large Telescope and the Gemini North telescope show two bright, overlapping spirals that look like glowing wings against the darkness of space, which is why astronomers nicknamed them the “Butterfly Galaxies.”

Who discovered them and what are their basic properties?

Both galaxies were discovered back in 1784 by the famous observer William Herschel, more than two centuries before we had any idea they were in the middle of a slow crash.

Each member of the pair is an unbarred spiral galaxy, meaning their arms wind directly out from a central bulge instead of sprouting from a long central bar.

Their spiral arms are packed with gas, dust, and young blue stars, which is a sign that star formation is still very active.

Here is a quick identity card for the system, using some SEO‑friendly phrases you might have already searched such as “Butterfly Galaxies distance,” “NGC 4567 galaxy type,” and “Virgo Cluster interacting galaxies.”

Property	Value
Official names	NGC 4567 & NGC 4568 (VV 219), also called Butterfly Galaxies
Galaxy type	Two unbarred spiral galaxies[web:3][web:5]
Distance	≈ 60 million light‑years from Earth
Constellation	Virgo
Environment	Members of the Virgo Cluster of galaxies

Astronomers once casually called them the “Siamese Twins,” but NASA and other institutions stopped using that nickname in 2020 to avoid offensive language in official communication.

Are these galaxies really colliding or just overlapping?

What clues do we see in the image?

At first glance, the Butterfly Galaxies look like two spirals that just happen to line up along our line of sight. The centers of NGC 4567 and NGC 4568 are still about 20 000 light‑years apart, and both disks largely keep their original pinwheel shapes, so the collision is only in its early stages. That is why this system is such a favorite in astronomy outreach—it is like catching a movie in the first few minutes, before the real drama starts.

Look closer, though, and the picture change. The overlapping region between the two disks is bright, dusty, and full of hot young stars, which hints that their mutual gravity is already stirring up gas and triggering new star formation.

How did ALMA and other telescopes prove the interaction?

To go beyond pretty pictures, astronomers turned radio and millimeter telescopes such as ALMA onto the pair to map neutral and molecular hydrogen gas. Those observations show continuous streams of gas connecting the two galaxies and clear distortions in the gas distribution, a smoking gun for tidal forces pulling material back and forth. Studies find that star‑formation activity is especially intense in the overlapping zone, where clouds are compressed by the collision and collapse into new stars at an increased rate.

In short, they are not just photobombing each other—the Butterfly Galaxies are firmly classed as an interacting pair, caught at the moment when the first serious gravitational handshake has started. That is why you often see them in scientific papers about tidally driven star formation and early‑stage galaxy mergers.

What happens during a galaxy collision like this?

Do stars actually crash into each other?

Here comes the “aha” moment that usually surprises people: when galaxies collide, almost none of the individual stars actually hit each other. Stars are tiny compared with the distances between them, so a galaxy is more like two huge swarms of bees passing through one another than two solid snowballs smashing together. The real chaos happens in the gas and dust, which are much more spread out and interact strongly.

Gravity stretches and warps the disks, throwing out long tidal tails and bending the spiral arms into weird shapes. Gas clouds slam into each other, compress, and collapse to form dense star‑forming regions, lighting up the galaxies with new clusters and sometimes feeding the central black holes. Over hundreds of millions of years, the two well‑ordered spirals gradually lose their neat structure and settle into a more rounded, fuzzy object we call an elliptical galaxy.

What will the Butterfly Galaxies become?

Simulations and observations of other interacting pairs suggest that NGC 4567 and NGC 4568 will fully merge into a single galaxy in about 500 million years. By that time, much of their gas will have been either turned into stars or blown away by stellar winds and supernova explosions, leaving a more quiescent, redder elliptical galaxy behind. Astronomers often point to their neighbor Messier 89—also in the Virgo Cluster—as a likely preview of what the final “Butterfly Remnant” might look like.

The timeline is long on human scales, but short compared with the age of the universe, which is about (13.8 \text{ billion years}). So, in the grand cosmic calendar, the Butterfly Galaxies are already in the middle of their relationship drama, even if it feels frozen to us.

What do the supernovae inside the Butterfly Galaxies tell us?

Which supernovae have exploded there?

Interacting galaxies are fertile ground for supernovae, and the Butterfly pair is no exception. Several stellar explosions have been recorded in NGC 4568, each offering a fresh chance to test models of how massive stars live and die. Different catalogues list slightly different details, but together they paint a clear picture: this is an active stellar nursery with stars already reaching the end of their lives.

Here is a simple overview of some of the better‑known supernovae in the system.

Supernova	Type	Galaxy	Discovery year
SN 1990B	Type Ib/Ic core‑collapse	NGC 4568	1990
SN 2004cc	Type Ic	NGC 4568	2004
SN 2020fqv	Type IIb	NGC 4568	2020
SN 2023ijd	Type II	Butterfly system	2023

So when you see that bright knot in one of the spiral arms in some images, you are sometimes looking at the fading glow of a star that has literally torn itself apart.

Why was SN 2020fqv such a big deal?

SN 2020fqv, discovered in 2020, quickly became one of the best‑observed core‑collapse supernovae in history. Astronomers already had pre‑explosion images of its progenitor star from Hubble and other telescopes, so when the star blew up, they could compare “before” and “after” in incredible detail. NASA called it a “Rosetta Stone” supernova, because it helped link models of how massive stars lose mass with what we actually see in the first hours and days after the explosion.

For the Butterfly Galaxies, SN 2020fqv is like a lab experiment running inside a natural particle accelerator. The fact that it occurred in an interacting system rich in star formation makes it even more valuable, since many bright supernovae in the distant universe also erupt inside merging galaxies.

Could something like this happen to our Milky Way?

Are we on a collision course too?

Short answer: yes, but do not lose sleep over it. Our Milky Way is currently moving toward the Andromeda Galaxy, and the two are expected to start seriously interacting in about 4–5 billion years. Computer simulations show long tidal tails, twisted disks, and a final merged object that would probably be a large elliptical or lenticular galaxy, much like what is expected for NGC 4567 and NGC 4568.

So when people search for “what happens when galaxies collide” or “will the Milky Way collide with Andromeda,” the Butterfly Galaxies are a very relevant example. They show an early stage of the same type of event, just playing out far away in Virgo instead of in our own backyard.

What would the night sky look like?

If any hypothetical observers were living on a planet in one of the Butterfly Galaxies, their night sky would be jaw‑dropping. Over millions of years, the companion galaxy would grow larger and more distorted in their sky, filling it with bright streams of stars and glowing gas. For them, a long‑exposure astrophoto would almost be redundant—the sky itself would already look like a cosmic painting.

For future Earth‑like observers during the Milky Way–Andromeda encounter, simulations suggest that Andromeda could stretch across a huge portion of the sky, far brighter than our current Milky Way band. Again, most stars would not collide, but the overall structure of both galaxies would be drastically reshaped.

Why do astronomers care so much about NGC 4567 and NGC 4568?

What do they teach us about star formation?

Interacting galaxies are natural laboratories for extreme star formation, or starbursts, which are important for understanding how galaxies grow over cosmic time. Studies of the Butterfly pair show that molecular clouds in the overlapping region are denser and more turbulent than in calmer parts of the disks, and those conditions lead to higher star‑formation rates. That connects directly to a bigger question: how do galaxy collisions turn available gas into stars, and why do some mergers trigger huge bursts while others stay relatively quiet?

By carefully measuring the mass, temperature, and motion of molecular gas, astronomers can test theories of tidally induced star formation and compare them with large surveys of interacting systems. In other words, the Butterfly Galaxies help turn “galaxy collision” from a dramatic phrase into a quantitative science.

How do they fit into the story of galaxy evolution?

Galaxy evolution models suggest that many giant elliptical galaxies in clusters like Virgo are the end products of spiral–spiral mergers similar to NGC 4567 and NGC 4568.[web:6][web:12] By catching systems in different stages—from just‑starting interactions like the Butterfly pair to more advanced mergers like the Antennae Galaxies—astronomers can assemble a kind of time‑lapse of how structure changes.[web:6][web:3] That “time‑lapse” is built not from one galaxy aging, but from comparing many systems at different points in the process.

The Butterfly Galaxies are especially valuable because their disks are only mildly disturbed so far, which makes it easier to measure their original properties and see exactly what the interaction has already changed. They sit at a sweet spot where the story is already interesting, but not yet too chaotic to analyze.

What are people usually asking about these galaxies?

Are the Butterfly Galaxies visible with amateur telescopes?

Under dark skies, a medium‑sized amateur telescope (around 20–25 cm aperture) can show the Butterfly Galaxies as two small, fuzzy patches touching each other. With larger instruments or long‑exposure astrophotography, observers can begin to see the stretched shapes and brighter center regions that hint at their interaction. So if you are searching “how to observe NGC 4567 and NGC 4568,” the short answer is: a good telescope, dark skies, and patience.[web:5][web:20]

Do galaxy collisions threaten life?

On human timescales, no, and even on cosmic timescales, life might be safer than you expect.[web:3][web:6] While gravitational interactions can disturb planetary orbits near the galactic center or in dense clusters, our Sun sits in a fairly quiet suburb of the Milky Way.[web:3][web:12] Even during the future collision with Andromeda, models suggest our Solar System is likely to drift into a new orbit rather than be thrown into deep space or a black hole.

So the Butterfly Galaxies are more like a beautiful warning sign that the universe is never static, not a direct threat. Their story reminds us that change is built into the fabric of the cosmos, right down to the galaxies themselves.

How does this connect back to us?

What personal insight can we draw from a pair of colliding galaxies?

There is something strangely human about watching the Butterfly Galaxies twist and overlap in that famous image. Two graceful spirals are pulled out of shape by a force they cannot ignore, yet out of that chaos, new stars are born in their shared, glowing center.

It echoes how big changes in our own lives often feel like collisions, but they can also create new “stars” in the form of ideas, relationships, or projects we never expected.

As a science community and as readers of FreeAstroScience, we stay curious not just to admire the universe, but to understand our place in it. By the way, every time we look at NGC 4567 and NGC 4568, we are also getting a sneak peek at the distant future of our own galaxy—and that is a pretty wild thought to carry with you on a regular Tuesday.

Conclusion

So, what have we really learned from this cosmic butterfly? We saw that the Butterfly Galaxies—NGC 4567 and NGC 4568—are a pair of unbarred spiral galaxies in the Virgo Cluster, around 60 million light‑years away, already locked in a slow collision that will eventually merge them into one elliptical system.

We explored how radio and millimeter observations from facilities like ALMA revealed disturbed gas and enhanced star formation in their overlapping region, proving that they are interacting and giving us a front‑row seat to tidally driven star formation. We also met the supernova SN 2020fqv, a “Rosetta Stone” explosion that turned this galaxy pair into a laboratory for studying how massive stars die.

On a more personal level, the Butterfly Galaxies offer a mirror for our own future, since the Milky Way and Andromeda are headed for a similar encounter in a few billion years. Anyway, that distant fate invites us not to panic but to stay curious, to keep learning, and to remember that change—whether in galaxies or in our own lives—can create new beauty as well as disruption. This article was written for you by FreeAstroScience.com, a site dedicated to making complex science feel friendly and accessible, and you are warmly invited to come back, keep asking questions, and refuse the “sleep of reason” that breeds monsters.