The surface area of a sphere (any sphere) is 4 steradians. this means that the celestial sphere covers 41253 square degrees (3602/t) of the sky. the hudf image is a square of side length 2.4 arc-minutes, and 10,000 galaxies are estimated within the image. assuming the cosmological principle, how many billions of galaxies are there in the known universe?

The number of galaxies in the known universe is 257.83 billions.

Explanation:

Given that,

Surface area of sphere = 4 steradians

Area of  celestial sphere = 41253 degrees²

Side length  = 2.4 arc minutes

We know,

The area of the HUDF image is

The total number of galaxies in the image is 10000.

The area of  celestial sphere is

We need to calculate the number of galaxies in the known universe

Using formula for  the number of galaxies

Hence, The number of galaxies in the known universe is 257.83 billions.

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