GENERAL KNOWLEDGE

Detailed explanation-1: -Ever since 1929, when Edwin Hubble discovered that the Universe is expanding, we have known that most other galaxies are moving away from us. Light from these galaxies is shifted to longer (and this means redder) wavelengths-in other words, it is ‘red-shifted’.

Detailed explanation-2: -Astronomers also use redshift to measure approximate distances to very distant galaxies. The more distant an object, the more it will be redshifted. Some very distant objects may emit energy in the ultraviolet or even higher energy wavelengths.

Detailed explanation-3: -The galaxies are moving away from Earth because the fabric of space itself is expanding. While galaxies themselves are on the move-the Andromeda Galaxy and the Milky Way, for example, are on a collision course (opens in new tab)-there is an overall phenomenon of redshift happening as the universe gets bigger.

Detailed explanation-4: -They found that the larger the distance a galaxy is away from us, the larger the redshift of its spectral lines. If the redshift is due to a relative velocity between the galaxy and ourselves, this shows that the further away a galaxy is from us, the faster it moves away from us.