When you look at the night sky full of stars, try to focus on one star and you will notice that it is twinkling. Why does it happen? While many stars do change their brightness with time, they are called variable stars, it is rather slow process (could vary from days to years for example), so you shouldn’t see it with your naked eye.
The real reason for twinkling is our atmosphere, it’s thickness and density varies very quickly with time and that what makes stars change their brightness for our eyes. Atmosphere is a real bummer for astronomers and they try very tricky ways to compensate it’s effects. The simplest solution is to place telescope to space (now you know why Hubble’s photos are so cool ;-), but it is a really costly solution (now you know why we still have Earth based telescopes and bother with atmosphere).
You can see why astronomers fight with atmosphere effects. Atmosphere affects objects located close to horizon most, for example Sun at sunset. Click for a bigger version. Image credit: H. Jukushima
Another tricky high tech way is to deform telescope’s mirror in real time according to atmospheric conditions. This technology is called adaptive optics. It’s idea is not new, but only recently we reached required technical level to adopt it.
Starburst galaxy NGC7469 Left: imaged with adaptive optics. Right: without adaptive optics. Image Credit: Canada-France-Hawaii Telescope.
Tags: adaptive optics, astronomy, atmosphere, space telescope, Stargazing, stars twinkle
