2006-10-23 09:26:12 · 4 answers · asked by syrious 5 in Science & Mathematics ➔ Other - Science
While it is true the universe is expanding, things in the universe are still moving. Andromeda and the Milky Way are moving towards each other at a rate that is faster than the rate of expansion. Someday the two galaxies will colide, and it'll be awesome!
2006-10-23 09:31:54 · answer #1 · answered by ohmneo 3 · 1⤊ 0⤋
Galaxies need not move at the same speed.
If you rack the balls on a pool table, then break them, the 'rack' is expanding, but not all balls are moving at the same speed.
Scientists know the we are moving closer to andromeda due to the Doppler effect. It's the same effect that makes a train's or car's noise rise and fall in pitch as the move closer and farther away, respectively. The sound waves hit your ear at a faster rate when the car is moving towards you, and at a slower rate as it moves away.
Light is also a wave. As we move closer to Andromeda, the light waves hit our eyes (via telescope) at a faster rate, thus the wavelength of the light is shorter. Therefore, the light is skewed towards the red side of the spectrum. Galaxies that are moving away from us cause the wavelength of the light to be bigger, and therefore skewed to the violet side of the spectrum.
2006-10-23 16:36:27 · answer #2 · answered by Murph 2 · 1⤊ 1⤋
Because elements within the universe are not expanding relative to each other at the same rate?
Same idea as you overtaking a car. You are both travelling in the same direction, but at different speeds.
2006-10-23 16:28:36 · answer #3 · answered by Anonymous · 0⤊ 2⤋
The universe is not expanding !!!
we are not moving closer to Andromeda.
Th
2006-10-23 17:05:31 · answer #4 · answered by Thermo 6 · 0⤊ 2⤋