alt.hn

4/23/2026 at 6:11:29 PM

Astronomers find the edge of the Milky Way

 https://skyandtelescope.org/astronomy-news/astronomers-find-the-edge-of-the-milky-way/

by bookofjoe

4/24/2026 at 6:35:09 AM

Title: "Astronomers find the edge of the Milky Way"

First sentence in the article: "Astronomers have located the edge of the Milky Way’s star-forming disk for the first time"

Wouldn't you expect someone from a publication called "Sky & Telescope" to know that these two are different things?!

Also, in diagrams showing our galaxy, I would greatly appreciate a "you are here" marker which points out the location of our solar system...

by rob74

4/24/2026 at 10:41:21 AM

> Also, in diagrams showing our galaxy, I would greatly appreciate a "you are here" marker which points out the location of our solar system...

What would that mean?

Try locating France on this map: https://en.wikipedia.org/wiki/File:T_and_O_map_Guntherus_Zin...

by thaumasiotes

4/24/2026 at 11:26:47 AM

Ok, I would be happy with an approximate location too. On that map, I would place France in Europa right beside the mediterraneum, pretty much on the Occidens side (although not at the very edge).

by rob74

4/24/2026 at 12:34:03 PM

Well, to ask you again, what do you think "an approximate location" would mean? How would the labeling be done?

It's easy enough to take the rob74 position of "I'm going to choose an arbitrary point on this artist's conception and paste a 'you are here' sticker over it", but what would be the point?

by thaumasiotes

4/23/2026 at 8:51:22 PM

Is this a non-sequiter or just poorly phrased?

  > Disk galaxies like the Milky Way form stars “inside-out” — starting from the center and working outwards through the disk. So, as a general rule, the farther out astronomers look, the younger the stars are.
Do they meant looking out from Earth (which is actually nearer to the center of a spiral arm than to either end) or out from the galactic bulge. Either way doesn't make sense.

by dotancohen

4/24/2026 at 3:55:26 AM

To use an analogy, to add to everybody else: it's like rings on a tree stump. The innermost part of the stump is the oldest; the outer the youngest. Earth is on one of those in-between rings, neither the oldest nor the newest - doesn't matter which of the in-betweens, to be honest.

Suppose now that you're an ant on the middle ring of that tree stump. No matter which way you're looking from Earth's middle-ring, either the rings will get gradually older and then younger with increasing distance (if you're looking towards the center-ish), or the rings will get strictly younger (if you're looking away from the center-ish).

This analogy obviously breaks down if you delve into details but that should give a better intuition to what's going on.

by eventualcomp

4/23/2026 at 10:13:52 PM

When does "starting in the center" mean anything besides "starting in the center"?

The earth is not the center of the galaxy

by malfist

4/24/2026 at 4:32:16 AM

The Earth is where the astronomers are. If they are looking outward (away from the center) then the further they look, the younger the stars.

by furyofantares

4/23/2026 at 11:40:17 PM

He didn't say that. He said earth is nearer to the center of a spiral arm.

by assimpleaspossi

4/24/2026 at 3:51:05 AM

What does the center of a spiral arm have to do with the center of the galaxy?

by malfist

4/24/2026 at 11:48:08 AM

I don't know but that's not what I'm talking about.

by assimpleaspossi

4/24/2026 at 3:38:09 AM

the location of earth has precisely zero to do with the topic

by dylan604

4/24/2026 at 11:47:40 AM

And your reply has zero to do with what I'm talking about.

by assimpleaspossi

4/23/2026 at 10:12:51 PM

I actually am not following what the ambiguity is - stars farther out from the center are younger, no?

by happytoexplain

4/23/2026 at 10:45:41 PM

The Earth isn't the center of the galaxy, so this feels confusing/confused:

> So, as a general rule, the farther out astronomers look, the younger the stars are.

by kadoban

4/24/2026 at 4:11:24 AM

The father out from the center of the galaxy they look, the younger the stars are.

by rafram

4/24/2026 at 5:04:23 AM

The location of the Earth is completely irrelevant. "closer" and "farther" refer to the center of the galaxy.

by jibal

4/23/2026 at 9:01:23 PM

Poorly phrased. The most recent stars are on the edges. The inner stars were first, hence the “working outwards”.

by _factor

4/24/2026 at 9:12:06 AM

But why? Star forms when enough hydrogen (or maybe also helium) clusters together with gravity to spark fusion IIRC. The center of Milky way ain't some ultra dense place where stars are just trillions of kms from each other to support somehow earlier star formation.

Or did ie dark matter/energy somehow coalesce on the outer edge later? Milky way is supposed to be very old place, almost as old as universe itself so one would expect more homogeneous distribution, at least as a layperson.

by kakacik

4/24/2026 at 10:36:33 AM

You need certain density to start formation progress. Then you get more density as it drags more stuff via gravity from intergalactic void. So new stars form at edges when there is finally enough stuff pulled by gravity of whole galaxy to there for the formation to happen.

It seems that you need quite large concentrations(as in scale of whole universe average) to actually get to star formation. Otherwise stars would be uniform trough the universe.

Then again I am not astronomer.

by Ekaros

4/23/2026 at 11:11:59 PM

Looking from Earth at the stars closer to the center of a galaxy, they are found to be older. Looking from Earth at the stars closer to the edge of a galaxy, they are found to be younger.

by ww520

4/24/2026 at 5:01:38 AM

Earth isn't relevant. The stars at the center of the galaxy developed first, and development proceeded from the inside out, so the youngest stars are on the edge ... then they get older from there on out, as the stars beyond the edge broke away from the galaxy. The bottom of the age U is the location of the formative edge.

by jibal

4/24/2026 at 4:31:01 AM

From Earth (where astronomers are) looking "out"ward (away from the bulge).

by furyofantares

4/23/2026 at 10:49:50 PM

Try: "the farther out [from the center] astronomers look"

by JumpCrisscross

4/23/2026 at 8:59:45 PM

It is beyond obvious what they mean.

by colechristensen

4/23/2026 at 9:19:51 PM

[dead]

by layer8

4/24/2026 at 10:31:07 AM

How are claims like these verified?

by chirau

4/23/2026 at 8:47:57 PM

Just the daily post that makes me feel small and insignificant.

by neals

4/23/2026 at 8:49:24 PM

I prefer that feeling much more than the modern sense from social media where everyone is abnormally important

by dylan604

4/24/2026 at 3:11:59 AM

Seriously. Being meaningless and insignificant gives you more freedom, and nowhere to hide from what you do with it. I’ve never understood cosmic dread. It feels like a release valve instead of a threat.

by rambojohnson

4/24/2026 at 11:29:58 AM

I'm still searching for the location of the Restaurant at the end of the universe.

by hulitu

4/24/2026 at 10:30:30 AM

Oh thank goodness, I've been looking for that.

by TZubiri

4/24/2026 at 4:03:09 AM

Incredible. "Hi honey, what did you do at work today? Casually discovered the edge of the galaxy. How are you?"

by onchainintel

4/24/2026 at 6:41:06 AM

I think they have been looking for the edge for years, and the discovery had come gradually over some time. So I don't think that "casually" fits there and "today" doesn't make things better.

by ordu

4/23/2026 at 9:11:27 PM

Great. Next Laniakea

by yrcyrc

4/24/2026 at 8:48:15 AM

Looks like leaving the solar system was just the tutorial level。 Next main quest:breaking out of the Miky Way.

by xingyi_dev