My mom says the sun is much bigger than the earth. But how can they know? You can’t fly there anyway because the sun is very hot and you would burn yourself anyway. You can’t land on it with a rocket like on the moon, can you?
Answer
You can calculate how big the sun is if you know how far away it is. It’s like a church tower seems smaller when it’s further up. If you know exactly how far it is, you can determine how high it is.
But how do we know how far the sun is from us? There are different methods for that. For example, by measuring how fast the earth moves around the sun. By multiplying the speed of the Earth by the time it takes for it to orbit the Sun (and that time is one year), you know the circumference of the circle that the Earth describes around the Sun. And from the circumference of the circle you can deduce the radius of that circle, and that is the distance earth-sun.
We thus find that the sun is about 150 million kilometers away from us. From the angle that the sun makes in the sky, you can deduce that the radius of the sun is about 700 thousand kilometers, which is more than a hundred times as large as the radius of the earth.
Answered by
prof. Christopher Waelkens
Astronomy
Old Market 13 3000 Leuven
https://www.kuleuven.be/
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