How long andromeda galaxy

We do this by observing the galaxy and comparing what we expect to see from a galaxy at rest to what we actually see from Andromeda. Things moving away from us have light that is Doppler shifted toward the red end of the spectrum; things moving toward us have light shifted toward the blue. Based on Doppler shifting of its light, Andromeda is speeding toward us at 68 miles per second kilometers per second.

So how much closer to collision with Andromeda have we come in the past 2. If we assume Andromeda has been moving at the same speed without accelerating, then in the last 2. Considering that the galaxy itself is , light-years across give or take; this number is continually being revised , this is a small but significant mosey.

As Andromeda gets closer, the gravitational attraction between it and the Milky Way gets stronger and Andromeda accelerates in our direction. However, even a small angle between Andromeda and the Milky Way will affect when and how the two galaxies collide, which stars will be flung out of the galaxies, and which will stay in.

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How fast does a rocket have to travel to get into space? What was the first man-made object to reach another world? Currently, Andromeda and the Milky Way are about 2. Fueled by gravity, the two galaxies are hurtling toward one another at , kilometers per hour.

Then, the two galaxies will collide head-on and fly through one another, leaving gassy, starry tendrils in their wakes. For eons, the pair will continue to come together and fly apart, scrambling stars and redrawing constellations until eventually, after a billion or so years have passed, the two galaxies merge. Then, the solar system will have a new cosmic address: A giant elliptical galaxy, formed by the collision and merger of the Milky Way and Andromeda.

That science can forecast such events was the focus of the third episode of Cosmos: A Spacetime Odyssey. That Newton could describe the orbits of planets, and Halley the return of his eponymous comet, and contemporary astronomers, the end of the Milky Way — this gift of foresight is really a mathematical understanding of the physical laws that govern the movements of celestial bodies. Any life on the worlds of that far-off future should be safe, but they will be treated to an amazing, billion-year long light show.

The story starts in the early s, when astronomer Vesto Slipher measured the radial velocity of Andromeda — in other words, he calculated the speed at which the galaxy was moving toward or away from Earth. Slipher did this by looking for a telltale stretching or compression in the light from Andromeda arriving at Earth: Light from objects that are moving away from us is slightly stretched, or red-shifted.

Light from objects moving toward us is blue-shifted, or compressed. So Andromeda was zooming toward us — that much at least seemed clear. Whether its arrival would mean the end of the Milky Way was still uncertain. But the crash will definitely liven up the night sky for any creatures that are around on Earth 4. The new study was published this month in The Astrophysical Journal.

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