From Earth, the Sun looks like it moves across the sky in the daytime and appears to disappear at night. This is because the Earth is spinning towards the east. The Earth spins about its axis, an imaginary line that runs through the middle of the Earth between the North and South poles.
If i measure the recession velocities of 2 galaxies and galaxy a has a velocity twice that of galaxy b, the far of b if a is 200 mpc away is
The parsec () is a unit of length used to measure the large distances to astronomical objects outside the Solar System.
Although parsecs are used for the shorter distances within the Milky Way, multiples of parsecs are also required for the larger scales in the universe such as Kiloparsecs (kpc) is for the more distant objects within and around the Milky Way, megaparsecs (Mpc) for mid-distance galaxies, and gigaparsecs (Gpc) for many quasars and the most distant galaxies.
If i measure the recession velocities of 2 galaxies and galaxy a has a velocity twice that of galaxy b, how far away is b if a is 200 mpc away? Remember that