The Hubble law (28-9)

Question 1 of 3

Question

Hubble constant = 70 km/s/Mpc = $2.3 \times 10^{−18}\mathrm{s}^{-1}$

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Review

This direct proportionality is called the Hubble law, and the constant $H_0$ in Equation 28-9 is called the Hubble constant. Astronomers typically measure distances in the cosmos in parsecs (pc), a unit equal to 3.26 light-years. One light-year (ly) is the distance that light travels in one year, equal to $3.09 \times 10^{16} \mathrm{m}$ . The current best value of $H_0$ is about 70 km $/\ \mathrm{s}\ /\$ Mpc, where 1 Mpc = 1 megaparsec = $10^6\ \mathrm{pc} = 3.26 \times 10^6$ ly.