Hubble's Law
Hubble's Law states that the recessional velocity (v) of a galaxy is directly proportional to its distance (d) from us. The proportionality constant is the Hubble Constant (H₀).
* v = H₀ * d
Hubble Constant (H₀)
The Hubble Constant is currently estimated to be around 73.2 km/s/Mpc. This means that for every megaparsec (Mpc) further away a galaxy is, it appears to be moving 73.2 kilometers per second faster away from us.
Calculation
1. Distance: d = 200 Mpc
2. Hubble Constant: H₀ = 73.2 km/s/Mpc
Plugging into Hubble's Law:
* v = 73.2 km/s/Mpc * 200 Mpc
* v = 14640 km/s
Therefore, the recessional velocity of a galaxy at a distance of 200 Mpc is approximately 14,640 km/s.
Important Note:
* The Hubble Constant is not a fixed value and is still being refined by astronomers. Different measurements and techniques yield slightly different values.
* This calculation gives an approximate value. In reality, the expansion of the universe is not perfectly uniform, and the motion of galaxies is also influenced by their gravitational interactions with other galaxies.
