How the distance between earth and sun,and other stars is measured?Give details pl?

Answer 1

"Distance measurements began with astronomers of the renaissance using parallax across the face of the earth to determine the distance to nearby heavenly bodies. This method was eventually applied to stars (see parallax). The distances to nearby stars so determined were recently radically improved by the Hipparcos mission.

However, the parallax method soon fails as distances grow larger and becomes practically impossible at distances greater than about 200 light years. But there is a way out of this dilemma. In the early 1900s an astronomer named Henrietta Leavitt examined the relationship between the absolute magnitude and period of the variable stars known as Cepheid variables. She discovered that the period of the stars is directly proportional to their absolute magnitude. So, by determining the periods of these stars and thus their absolute magnitudes and comparing these with their apparent magnitude, the distance to the star can be determined.

By calibrating this by using some Cepheid variable to which the distance is known by the parallax method, we can find the distances to vastly more distant objects.

This method can be extended another step. If a cepheid is discovered in another galaxy, then that galaxy's distance can be determined. If it is part of a cluster, then the approximate distance to all the galaxies in the cluster can be found. By Hubble's law it is thought that the velocity of recession of an object is proportional to its distance from us. The exact speed is determined by Hubble's constant, H0. This can now be found from the cepheid method and thus distances to the most distant reaches of the universe can be found."

From Wikipedia, the free, online encyclopedia at:
http://en.wikipedia.org/wiki/Astronomical_distances

Hope this helps!

Answer 2

the closest star to Earth is Alpha Centauri, 4 easy years away, in accordance to a e book by technique of former astronaut Michael Collins. that is on no account achieveable to prevail throughout this star any time quickly!

Answer 3

it is measured with the help of light
time it takes light to travel = distance

Answer 4

the unit used is au i.e. astronomical unit
One astronomical unit=distance from earth to sun