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Question
The Sun is a hot plasma (ionized matter) with its inner core at a temperature exceeding 107 K, and its outer surface at a temperature of about 6000 K. At these high temperatures, no substance remains in a solid or liquid phase. In what range do you expect the mass density of the Sun to be, in the range of densities of solids and liquids or gases? Check if your guess is correct from the following data: mass of the Sun = 2.0 × 1030 kg, radius of the Sun = 7.0 × 108 m.
Solution
Mass of the Sun, M = 2.0 × 1030 kg
Radius of the Sun, R = 7.0 × 108 m
Volume of the Sun, `V = 4/3piR^3`
`=4/3xx3.14 xx(7.0xx10^8)^3`
`=88/21xx343 xx10^(24) = 1.434 xx 10^(27) m^3`
Density of the Sun = `"Mass"/"volume" = (2.0 xx 10^(30))/(1.434 xx 10^(27))`
= `1.392 xx 10^3 "kg/m"^3`
This is the order of density of solids and liquids, not gases. The high density of the sun is due to inward gravitational attraction on outer layers, due to the inner layers of the sun.
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