by Prof. Harold A. Geller of GMU
As we approach summer, one constellation you won’t be seeing in the night sky, is the well known Orion. The brightest star in the constellation Orion is commonly known as Betelgeuse. Actually, all stars are so far away that they are observed by our telescopes as points of light, not an object with height or breadth. However, in 1998, the Hubble Space Telescope, above the atmospheric jitter and fuzziness, captured a picture of Betelgeuse for the first time by an individual telescope.
Now when I say that a star is very far away, I am talking in terms of how long it would take light to reach us if it left the star today. In the specific instance of Betelgeuse, it takes light about 643 years to reach the Earth once it leaves the surface of Betelgeuse. Actually, Betelgeuse, like all stars doesn’t really have a surface, it is a ball of hot gas, called a plasma, because its temperature is so high, all of its atoms have shed their electrons and so all you have is a bunch of charged atoms called ions and a sea of electrons. (more…)