comparing the size of the Sun to Earth The diameter of the Sun is 1,392,000 km, while the equatorial diameter of the Earth is 12,756 km. Compared to the Earth the Sun is HUGE.

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Now we know the sizes of the Sun and Earth, here's a tricky question.

How many Earths could you fit inside the Sun? The ratio of the Sun's diameter to the Earth's diameter is 1,392,000/12756 = 109.1

This means the ratio of their volumes is 109.1 x 109.1 x 109.1, which is about 1,300,000,and that means that 1,300,000 Earths should fit inside the Sun. But hang on a minute..... Fitting FLAT Earths into a FLAT Sun would leave unfilled gaps so you couldn’t completely fill the Sun. If all the Earths stayed as solid balls, you could probably only fit about

960,000 into a ball the size of the Sun, because of all the wasted space in between. The question of 'exactly how many small balls of a given size can you fit into a larger ball' is a very difficult mathematical problem and has been puzzled over for a long time. We are grateful to Paul Farris who, having visited the Suntrek website, sent us his thoughts on this question (.doc file 87KB). Below is a model showing the number of Earths you can get inside the Sun. On the other hand if you could melt the Earth into a liquid and pour it into an empty sphere the size of the Sun, then you really could fit in the equivalent of about 1,300,000 Earths, as we calculated before. If all this makes your head hurt, you could try bombing your teacher with these answers. back to top