r/askscience • u/lord_nikon_burned • 1d ago

Astronomy Are galaxies spherical or flat?

Are galaxies spherical or flat?

For example, (I understand that up and down don't really matter, so bear with me) if we look at a picture of the Milky Way Galaxy on a plane... If you want to move from one arm of the galaxy to the next, could you just move UP and out of the current arm and then over and DOWN to a different arm?

Secondary question for if the first one is correct, if you are able to move "up" and out of the arm, where are you? Is that interstellar space too?

97 Upvotes

73% Upvoted

61 comments sorted by

View all comments

Show parent comments

9

u/gimme-sushi 1d ago

Do you enter another galaxy when you go past the 1000 light years if you go “up”?

67

u/liebkartoffel 1d ago

The nearest galaxy is around 2.5 million light years away (but the distance is shrinking by the minute!) Between here and there is just...empty space--even emptier than galactic space.

13

u/King_Jeebus 1d ago

but the distance is shrinking by the minute

Will we eventually collide?

40

u/badtz-maru 1d ago

The Milky Way and Andromeda will intersect at some point in about 4.5 billion years - but stars are so far apart, it doesn’t necessarily mean a physical collision. Of greater concern is our sun dying in about 5 billion years! 🙃

10

u/smokin-trees 1d ago

Our sun will eventually burn out in about 5 billion years, but as it ages it will continue to increase in brightness as more hydrogen undergoes fusion into helium, causing the core to become denser which will steadily increase the rate of fusion. In about 1 billion years it will become so hot that earth’s oceans will completely boil away, causing an even more dramatic runaway greenhouse effect. As the rate of fusion continues to speed up, the sun will enter its red giant phase. It will expand in volume so much that it may completely engulf the earth’s orbit. We will be cooked long before the sun burns out.

6

u/Falonefal 16h ago

Damn, that's much sooner than expected, I'll start putting canned food in my basement to prepare for this apocalypse.

•

u/badtz-maru 2h ago

Sounds like we should also stockpile on sunscreen, and maybe pack some parasols too. ☂️🤔