# Do the stars imaged by a telescope even exist at present? Tags: astrophysics - Score: 8 - Views: 2679 - Answers: 2 - Answered: yes - Asked by: Ajit - Asked: 2012-04-11 - Edited: 2012-12-21 - Site: physics ## Question I know that we now have telescopes which can capture the images of the stars and galaxies millions of light-years away from us. Does the telescope capture the past image of the star, i.e. the light which it emitted centuries ago? What guarantee is there that the star is still alive? What basis do organizations like NASA plan missions for evading such stars? ## Answers ### Answer by Warrick (score: 17 [ACCEPTED]) For a star of a given mass, we can calculate, based on theoretical models, how long it has to live. For example, the Sun is currently 5 Gyr old and will live another 5 Gyr. So if you observe the Sun from, say, Andromeda, the light would be about 2 million years old and you could therefore conclude that the Sun is still alive even though you're observing "old" light. If you flip it around, if we see a Sun-like star in Andromeda, we could safely say it's still alive. Broadly, while fusing hydrogen in their cores, more massive (and therefore brighte