According to modern astronomers,into how many constellations is the whole sky divided?

The speed of recession of a galaxy is proportional to its distance.

$A$ bright star is indicated to have a brightness magnitude of $-5$ compared to a star of brightness zero magnitude. It means that this star,compared to the reference star of zero brightness,is:

Venus looks brighter than other stars because

If a galaxy is at a distance of $430$ million light years from us,what is the Hubble's constant in $km s^{-1}$ per million light years? Its speed is $6.48 \times 10^6 m s^{-1}$.

The age of the universe is believed to be