Alltimegreat1 said:Since space is rapidly expanding between galaxies, why are the Milky Way and Andromeda galaxies on a collision course with each other? Do galaxies need to be a certain distance apart for the force of their gravity to be weak enough so that it cannot overcome the expansion of space? Or is it because the Milky Way and Andromeda galaxies are simply moving toward each other as part of their orbits around the Great Attractor?
The two galaxies are approaching each other because their combined speed is faster than the rate the universe is expanding. Presently, the best estimate puts the rate of expansion of the universe at 67.80 ± 0.77 (km/s)/Mpc. Since we are measuring the approach of the Andromeda galaxy at ≈110 km/s, that must mean the Milky Way and Andromeda galaxies are actually approaching each other at a combined rate of ≈162 km/s in order to overcome the expansion of the universe which would be ≈52.18 ± 0.6 km/s at the distance of the Andromeda galaxy (0.78 Mpc).Alltimegreat1 said:Since space is rapidly expanding between galaxies, why are the Milky Way and Andromeda galaxies on a collision course with each other? Do galaxies need to be a certain distance apart for the force of their gravity to be weak enough so that it cannot overcome the expansion of space? Or is it because the Milky Way and Andromeda galaxies are simply moving toward each other as part of their orbits around the Great Attractor?
Galaxies within a cluster are gravitationally bound and can be moving relative to each other regardless of overall expansion of space.Alltimegreat1 said:... speeds that galaxies are traveling, what is meant by this? Are galaxies moving just because they're orbiting some central point of a galaxy cluster? Are all galaxies moving in a specific direction irrespective of the expansion of space?
Assuming the Earth is not consumed when the sun reaches its Red Giant phase ≈5 billion years from now, the Earth would still be rendered into a charcoal briquette. By the time the sun reaches its degenerate white dwarf phase it will lose ≈70% of its mass, which will effect Earth's orbit (as well as the orbits of all the objects in our solar system). Regardless of whether Earth remains in orbit around the white dwarf, or is thrown out of the solar system completely, it will become a frozen ice ball. Either way, humans will have to leave Earth within the next 500 million years, assuming we make it that long. Odds are that humans will become extinct long before that.Alltimegreat1 said:Assuming the Earth and humanity still exist in 1 trillion years, what would our observable universe look like? Would the other galaxies in our cluster still be around?
Alltimegreat1 said:Assuming the Earth and humanity still exist in 1 trillion years, what would our observable universe look like? Would the other galaxies in our cluster still be around?
The Andromeda-Milky Way collision refers to the future event in which the Andromeda galaxy and our own Milky Way galaxy will collide and eventually merge into one larger galaxy.
The collision is estimated to occur in about 4.5 billion years.
The collision will not have a significant impact on Earth as it is expected to survive the merging of the galaxies. However, the night sky will look drastically different as the two galaxies merge and form a new galactic shape.
Scientists have observed the motion of stars and galaxies and have predicted their future movements. Through these observations and calculations, they have determined that the collision between Andromeda and the Milky Way is inevitable.
The result will be a larger, elliptical galaxy formed from the merging of Andromeda and the Milky Way. This new galaxy will contain billions of stars and may have a different structure and appearance than either of the two individual galaxies.