Hello.
What are the advantages of using the Parsec over the lightyear?
This is urgent.
2006-11-05 16:38:12 · 7 answers · asked by Anonymous in Science & Mathematics ➔ Astronomy & Space
A Parsec is a parallax-arcsecond, and equal to 3.26 light-years. It's really *not* a much larger distance than a light-year, but it's a useful one for the following reasons:
If we look at a close star in January and then in June, the Earth will be on opposite sides of the Sun at each of those times. Although the Earth's distance to the Sun is only a very small fraction of our distance from the star, it will cause stars to slightly shift in the sky from this "binocular vision" perspective effect. This is what's known as parallax. Stars which are closer will shift more, and we can use the amount of parallax shift to tell how far away it is.
A star which shifts 1 arcsecond (1/3600th of a degree) will be exactly 1 parsec away. If it shifts only 1/2 of an arc-second, it's 2 parsecs away, 1/3 of an arc-second, 3 parsecs away, etc. So, that's one advantage to using it - it makes your parallax to distance conversion really easy.
Another advantage is that parallax is tied to the Astronomical Unit (AU) which is the distance between the Earth and the Sun. Because of how the parallax geometry works out, it makes it such that the number of arc-seconds in a radian is exactly equal to the number of AU in a parsec: 206265. This makes converting between solar system distances and interstellar distances very easy.
2006-11-05 16:52:51 · answer #1 · answered by Mike 2 · 1⤊ 0⤋
If you know how many seconds of arc an object subtends, then you can find its distance using parsecs.
The parsec and the lightyear are in the same order of magnitude. 1 parsec ~ 3.something lightyear.
2006-11-06 00:52:00 · answer #2 · answered by Dr. J. 6 · 0⤊ 0⤋
The parsec is a much larger distance, so it is more appropriate for measuring extremely large interstellar distances.
In the same way that you measure the length of a car trip in miles, not feet, you would measure the distance to a distant galaxy in parsecs, rather than light-years.
2006-11-06 00:46:46 · answer #3 · answered by actuator 5 · 1⤊ 0⤋
What's the advantage of using yards over feet (the ratio of one to the other is fairly close to that between parsecs and light-years)?
2006-11-06 03:55:43 · answer #4 · answered by The Sage on the Hudson 2 · 0⤊ 0⤋
1 parsec is approximately 3.26 lightyears, so it makes measuring great distances slightly easier. however, most astronomers and scientists prefer the lightyear even for the super long distances...
Also, parsecs can be expressed in these forms
Parsec (1 parsec)
Kiloparsec (1000 parsecs)
Megaparsec (1,000,000 parsecs)
Gigaparsec (1,000,000,000 parsecs)
This allows great distances to be stated much easier... rather than saying "three-billion-two-hundred-sixty-million light years from earth, you can say "3.26 Gigaparsecs from earth."
2006-11-06 00:57:47 · answer #5 · answered by Occam's Pitbull 6 · 0⤊ 0⤋
Why is it urgent? You planning a trip?
2006-11-06 00:48:40 · answer #6 · answered by Anonymous · 0⤊ 1⤋
go to "online conversions and you may find the answere there
2006-11-06 00:44:26 · answer #7 · answered by mickkooz 4 · 1⤊ 0⤋