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: -When an object is moving away from us, the light from the object is known as redshift, and when an object is moving towards us, the light from the object is known as blueshift. Astronomers use redshift and blueshift to deduce how far an object is away from Earth, the concept is key to charting the universe’s expansion.

Detailed explanation-3: -Light emitted from galaxies moving toward you would be squished, making the wavelength shorter and the light bluer. On earth, we perceive the light from galaxies moving away from us (as it appears almost all galaxies are) . . . . as being somewhat stretched, with longer wavelengths that make it look redder.

Detailed explanation-4: -The fabric of space expands. This is the cause primarily responsible for the redshifting we see of distant galaxies. Light travels through the fabric of space, which is expanding as time progresses since the Big Bang, and that expanding space stretches the wavelength of the light that travels through it.