Question:
I'm a 6th grade science teacher and my students want to know how
scientists are able to determine the temperature of the sun's surface and it's
core. Also the temps of the other planets in our solar system, especially
Pluto.
Replies:
The temperature of the surface of the Sun can be determined in various
ways. We know how much energy we receive on Earth per unit time over a unit area
facing the Sun. Then knowing the distance to the Sun, we can estimate total
energy being emitted by the Sun. The total energy emitted per unit time per unit area is related to
temperature in a known way. This can be used to find the Surface temperature of
the Sun.
Sun is a gaseous sphere and it seems to be a stable object. Our existence tells
us about the stability of the Sun. We think that gravity holds the Sun together.
In that case the gas pressure must be enough to balance the gravitational force.
We know the relation between gas pressure and temperature, this is then used to calculate the
core temperature. This is the simplest method i know of, other methods take into
account some other effects as well but answers don't change much.
Temperature of Planets is measured in a slightly more complicated way
Known properties of reflected light are used to probe the reflecting material,
here the Planets' atmosphere.
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