OK, so the universe is still expanding and galaxies are moving away from each other, so why is it that we will collide with andromeda and our galaxies will merge.
Also, im told that although the universe is expanding, this only means the space between the galaxies is growing and the galaxies themselves stay the same size, why?
2006-09-25 00:27:36 · 14 answers · asked by Jason 2 in Science & Mathematics ➔ Astronomy & Space
Galexies are held together by gravity. The matter in them is attracted to the other matter in them. This is why they don't fly appart. It's the same reason the earth doesn't fly away from the sun; just on a much bigger scale.
The fact our galexy is going to colide with andromeda is for the same reason: We're being pulled together by gravity. The massive black holes in the centre of each gallexy is being forced towards the other one. We are close enough that the force cannot be countered by the expanding universe.
2006-09-25 00:33:22 · answer #1 · answered by adder_86 2 · 0⤊ 2⤋
The expansion is an overall tendency which is increased as the distance between galaxies gets larger. For very close galaxies, the rate of expansion is fairly small and is overwhelmed by the gravity of the galaxies themselves. The Andromeda galaxy is very close by galactic standards, so the gravity betwen our Milky Way and it actually makes them grow closer together.
A similar consideration applies for the galaxies themselves. To really see the expansion effects, you have to have distances on the order of tens to hundreds of millions of light years. Galaxies are 'only' a few hundred thousand lightyears across. Because of this, the gravity inside the galaxies is stronger than the expansion.
2006-09-26 04:54:55 · answer #2 · answered by mathematician 7 · 0⤊ 0⤋
Yes the universe is expanding at an ever increasing rate!..But galaxys are clumping together because of gravitational attraction!.. the space between these 'clumps' is increasing but the 'clumped' galaxys are still tugging at each other!..Our milkyway galaxy is slowly but surely absorbing gravitationaly, both the large and small Magellanic clouds!..These are small galaxys orbiting the milky way about 160,000 light years away!..Our galaxy and the spiral in Andromeda, about 4 million light years apart are gravitationaly joined and will, eventually merge and become one!..But the local 'clump' we belong in is still whizzing apart from the other 'clumps'!..
2006-09-25 01:06:12 · answer #3 · answered by paranthropus2001 3 · 0⤊ 0⤋
The galaxies will only collide if one of the theories regarding the universe is correct. In this theory, the universe will stop expanding as it loses momentum. It will then start to contract again. Imagine a balloon being blown up and then slowly being let down.
As the universe gets smaller and smaller, the galaxies will get closer and closer and eventually collide.
Dont panic tho - we are talking billions of years from now and that's only if the theory is right. Other theories predict the universe will continue to expand or will stop and stay as it is!
Either way, before this happens our Sun will have destroyed itslef (and us)!
2006-09-25 00:48:23 · answer #4 · answered by Anonymous · 0⤊ 0⤋
The reality that the Universe is increasing is an approximation that holds on the biggest scales. on the very greatest scales, larger than 100 Megaparsecs, it really is an spectacular approximation. Futhermore, it signifies that "area" is surely increasing, the spacetime manifold, and each and every thing in it, is increasing. On small scales, even if, the spacetime manifold should be strong or contracting. areas the dimensions of a cluster of galaxies and smaller at the prompt are not increasing---they're contracting. If the community density exceeds a severe density, then that area will settlement. The Earth, the picture voltaic gadget, the community crew of galaxies, and the Virgo supercluster at the prompt are not increasing---they're contracting or more beneficial-or-a lot less strong.
2016-10-16 02:10:42 · answer #5 · answered by ? 4 · 0⤊ 0⤋
Expansion is not uniform. If you were to set of an explosion, some of the piece blown away would collide with each other. Not all trajectories are the same, some of them are bound to intersect.
Also, the galaxies are expanding. Their shapes are held more firm as a result of the gravitational forces of the stars on each other, but they do change shape, and over time, tend to spread out as well.
2006-09-25 00:37:40 · answer #6 · answered by Anonymous · 0⤊ 0⤋
Galaxies are not evenly distributed throughout the universe. Many are located within local groups. While all the groups seem to be flying apart with the continued expansion of the universe, galaxies within a local group may be converging due to forces of gravity relative to the speed and direction of their masses.
Many picture the universe as a balloon that is expanding. I prefer to picture it as a "solid" globe of material that can swell (like a ball of rising dough due to yeast). If the dough was laced with sesame seeds (galaxies!) every seed would become more distant from every other seed during the expansion and there could be stretches of void (vacuum or gas bubbles) and hydrogen (dough) surrounding the seeds. The seeds are rich with atoms and molecules (stars and planets, etc.).
2006-09-25 01:24:45 · answer #7 · answered by Kes 7 · 0⤊ 0⤋
Galaxies do collide - the Milky Way is going to collide with the Andromeda galaxy - but not in your lifetime!
2006-09-25 00:37:17 · answer #8 · answered by Trillian 2 · 0⤊ 0⤋
Galaxies are moving, our Milky Way year is 250 million years! The Milky Way has collisioned with the Magallanic Clouds. When a galaxy collides, it absorbs part of the galaxy it collided with.
2006-09-25 12:13:43 · answer #9 · answered by Lara Croft 3 · 0⤊ 0⤋
Yes …the Milky Way and the Andromeda galaxy will collide...in a few billion years.
As I'm not an astrophysicist - I googled this & found this: http://www.space.com/scienceastronomy/astronomy/galaxy_collides_020507-1.html
2006-09-25 00:46:01 · answer #10 · answered by Mr Crusty 5 · 0⤊ 0⤋