View Deneb, one of the most distant stars
Print Me Email to FriendTonight is Monday, May 26 2008
The star Deneb – visible now by mid-evening – is one of the most distant of the bright stars. When you gaze at this star, you are gazing across a distance of 1,500 light-years away, according to the Observer’s Handbook. Meanwhile, Wikipedia places Deneb’s distance at 3,200 light-years.
Why the difference? It might relate in part to the way that science itself is done. Science is not a body of facts. It’s a process. Different astronomers or teams of astronomers occasionally try to improve on published distance estimates to the stars, and their various estimates are then published and passed along.
The distance to Deneb is estimated by stellar parallax, whose basic principle you can demonstrate to yourself by holding a finger in front of your nose and gazing at it with one eye closed, then the other eye closed. When you do this, you see your finger appear to jump from side to side with respect to background objects. If you hold your finger farther from your nose, it’ll appear to jump a smaller distance.
As Earth orbits the sun, astronomers can measure the locations of stars against the starry background, first from one side of Earth’s orbit and then – six months later – from the opposite side. The shift of stars due to parallax is exceedingly subtle, however, and subject to errors, which you can read about on Wikipedia’s parallax page.
Well, do I feel a fool…I found what I thought was missing! What a wonderful way to travel the universe! Thank you, thank you, and thank you!
Thank you, Nancy, for taking the time to visit and read our articles …
Deborah