Where Alpha Centauri and other nearby stars will be in the future

Monday, June 16, 2008

Here's an image on the German Wikipedia not present in the English one (image comes from here):

What it shows is the distance of stars near to Earth (in light-years, on the left side going from 0 up to 10), and the time in thousands of years on the x axis at the bottom. That makes the far left side 20,000 years ago, two spaces over at zero is the present, and the far right is 80,000 years in the future. The horizontal yellow line is the position of Proxima Centauri (the closest star to our solar system) for comparison, and the grey part at the bottom is the outer extent of the Oort Cloud.

You can see that only 20,000 years ago Alpha Centauri was 6 LY away instead of the 4.3 now, and it's now not only the closest star system but also moving closer every day. 25,000 years from now it'll reach its closest point to Earth at just a bit over 3 LY. Barnard's Star, the brown line moving in from the top left at a much steeper rate, is approaching our system at a much faster rate. You can tell how fast a star system is approaching by its radial velocity rate, which in Alpha Centauri's case is -21.6 km/s (negative means it's coming this way). Since the beginning of the space race for example (51 years or 1 609 403 226 seconds ago), Alpha Centauri has come 34 763 109 681 km closer, or 232 AU, almost eight times the distance from the sun to Neptune.

That's not much, but it's good to know at least that the closest star system to ours (and an especially interesting one as well) is getting closer to us and not the other way around (which would be the case if it were 30,000 years from now).


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