How do scientist weigh a star such as the sun?

Answer 1

It cannot. weight is a measurement of gravity between two objects. For example if I weigh 60 N on earth I would weigh around 10 N on the moon.

What you probably meant was how can the suns mass be measured; this can be done by taking the density multiplied by size.

Answer 2

A mass produces gravitation. The Sun attracts the planets, keeping them in their orbit. The things that need to be figured out for the calculation are:

• The gravitational constant. This can be measured in labs on Earth, for example, with a Cavendish balance (torsion balance).
• The distance from a planet to the Sun.
• Some details of said planet's orbit.
  

Answer 3

A barometer can be used to measure the weight of air.

See related links, below, for other methods.

Answer 4

One can know the mass of the Sun by measuring the distance and velocity of a planet orbiting the Sun.

Answer 5

joules