Some photographs, taken by large telescopes, show the brightest stars with points radiating from them. In reality, of course, stars do not have points. They are huge spherical balls of gas, just like the Sun, and because they are so far away they appear as pinpoints of light in even the most powerful telescopes. On Earth, atmospheric turbulence blurs the images of stars, but this does not affect photographs taken from space. Instead, the size of the star’s image is governed by light being bent at the edge of a lens, which scatters it into a small disc. At the same time, supports for the secondary mirror inside a telescope also diffract the light-and this is what produces the radiating points.
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