Space photo of the week: Astronomers make an 'artificial star' over Hawaii
What it is: The Gemini North telescope When it was published: Feb. 7, 2024 Where it is: The Gemini Observatory at the summit of Mauna Kea in Hawaii Why it's so special: Stars twinkle — and that isn't good if you want to study them using large telescopes. The twinkling comes from light passing through different layers of Earth's turbulent atmosphere, which leads to a blurry, jumpy image in a telescope. Astronomers call this effect poor "seeing," and it can interrupt Astronomy for many nights — or, at least, it used to. On the Gemini North telescope, as on many modern ground-based telescopes, astronomers now use adaptive optics, which allows the telescope to correct for the distortions created by Earth's atmosphere. From the top of Gemini North, a yellow laser called TOPTICA is used to make an artificial star on traces of sodium gas in the atmosphere about 50 miles (80 kilometers) over Earth. Computers then deform the telescope's mirrors slightly ...