Question

What is Hubble's Constant and how was it found?

Answer 1

the ratio of speed of recession of galaxy (due to expansion ) of universe) to its distance from observer is called hubble's constant.
it was simply derived from general relativity equations

Answer 2

Galaxies appeared to recede, one from another.

Any apparent space motion of one space body is relative to the

motion of another.

Motion of galaxies is like motion of space islands.

The velocity of a galaxy is estimated by Doppler;s effect that light

emitted from a source is shifted in wave length, by the motion of the

light source.

A galaxy is a compounded source of lights from its

innumerable constituent stars..

In respect of this motion, Edwin Powell Hubble (1889-

1953) discovered in 1929 a linear correlation between speed and

distance:

Rate of change of speed with respect to distance is constant.

This Hubble constant `H_0` = 71 km/sec/parsec.

After converting units to a befitting form, the age of our universe

is estimated as 1/`H_0` = 13.77 billion years.We are able to

estimate

Clarification means 'answering anticipated queries'. For the query

'How is that?':

If T denote the dimension time,

`[H_0]= T^(-1)`, and so, `[1/ [H_0 ]]=T`