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observed in its emitted spectrum. One application of Hubble's law is to estimate distances to galaxies based on measurements of their recessional velocities. However, for relatively nearby galaxies the peculiar velocity can be comparable to or larger than the recessional velocity, in which case
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is the relationship between a galaxy's distance and its recessional velocity, which is approximately linear for galaxies at distances of up to a few hundred
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Hubble's Law does not give a good estimate of an object's distance based on its redshift. In some cases (such as the
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is negative (i.e., the galaxy's spectrum is observed to be blueshifted) as a result of the peculiar velocity.
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The rate at which an astronomical object becomes more distant from an observer
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object recedes (becomes more distant) from an observer as a result of the
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at 12 million light-years away and approaching at 34 km/s)
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The recessional velocity of a galaxy can be calculated from the
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219:{\displaystyle v_{r}=H_{0}D\ +v_{pec}}
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158:. It can be expressed as
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388:{\displaystyle v_{r}}
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304:{\displaystyle v_{r}}
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249:{\displaystyle H_{0}}
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141:cosmological redshift
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