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# stellar distances watch

1. can someone gimme a explanation about the parsec and parallax method etc?
2. (Original post by SennaRacer77)
can someone gimme a explanation about the parsec and parallax method etc?
Parallax is one method of measuring the distances to stars that are relatively close by. It relies on the fact that when an object that is at a fixed distance relative to the observer is viewed from two different positions, each being the same distance from the object, the object appears to move. The further away the object is, the less it appears to move.

A star is viewed from Earth twice with a 6 month interval between each viewing. This is because after 6 months, the Earth will be at the furthest point away in its orbit, so it is easier to measure the apparent movement of the star. Then the angle through which the star appears to have moved is noted; the parallax angle is half of this angle.

Parallax angles are usually given in "seconds of arc" because they are so small since stars are far away. There are 360 degrees in a circle. In each degree, there are 60 minutes and in each minute, there are 60 seconds. The minutes and seconds here are usually referred to as "minutes of arc" and "seconds of arc" to avoid confusion with the minutes and seconds used for time.

A parsec is a measure of distance. It is defined as the distance at which an object will have a parallax angle of 1 second of arc; it is approximately equal to 3.22 light years. The distance to a star in space, measured in parsecs, is the reciprocal of its parallax angle.
3. omg thanks!
4. (Original post by SennaRacer77)
omg thanks!
You are welcome.

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