The redshift of very distant galaxies is mainly due to the expansion of space whilst the light has been travelling towards us.
The basic relationship (at non-relativistic speeds) is that v=H0d where v is the velocity implied by the redshift and d is the distance..
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.
As the light travels great distances and is redshifted, its wavelength may be shifted by a factor of 10..
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.
As the light travels great distances and is redshifted, its wavelength may be shifted by a factor of 10..
'Red shift' is a key concept for astronomers.
The term can be understood literally - the wavelength of the light is stretched, so the light is seen as 'shifted' towards the red part of the spectrum.
Something similar happens to sound waves when a source of sound moves relative to an observer..
In the widely accepted cosmological model based on general relativity, redshift is mainly a result of the expansion of space: this means that the farther away a galaxy is from us, the more the space has expanded in the time since the light left that galaxy, so the more the light has been stretched, the more redshifted .
When Hubble plotted the redshift vs. the distance of the galaxies, he found a surprising relation: more distant galaxies are moving faster away from us..
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.
As the light travels great distances and is redshifted, its wavelength may be shifted by a factor of 10..
In general, cosmological redshifts are not the same as Doppler shifts.
Redshifts can be measured very accurately.
A typical velocity measurement for a galaxy might be 12,540 ± 120 km/s, which corresponds to a redshift of z = v / c = 12,540 / 3x 10 5 = 0.0418.
Now since cosmological measurements in recent years have led to a concordance on what energy forms pervade our universe, it is now possible to make a simple table relating observed cosmological redshift, labeled "z", with standard concepts of distance and time, including:
The Hubble law's linear relationship between distance and redshift assumes that the rate of expansion of the universe is constant.
However, when the universe was much younger, the expansion rate, and thus the Hubble "constant", was larger than it is today.
