A football and a peppercorn

About this video

The Earth is about 150 million kilometres from the Sun, a number far too big to picture. So shrink everything by the same amount.

Make the Sun a football 20 centimetres across. Then the Earth is a peppercorn 21 big steps away, and the Moon is a grain of sand 5.5 centimetres from the peppercorn. Every trip people have ever made in space fits in that gap.

Now walk out from the football, counting steps of about a metre. Mercury, a pinhead, is at 8 steps. Venus, a peppercorn, is at 15. The Earth is at 21, and Mars, another pinhead, at 33. All four rocky planets are within 33 steps of the football. Keep walking: Jupiter, a grape, is at 112 steps; Saturn, a smaller grape, at 206; Uranus, a pea, at 412; and Neptune, another pea, about 650 steps out. Between them there is almost nothing: the solar system is mostly empty space.

And the nearest star? If the football Sun were in Madrid, the nearest star would be another football in New York, about 5,800 kilometres away.

Even light takes time to cross the solar system. Sunlight takes about 8 minutes to reach the Earth and about 4 hours to reach Neptune.

This is why pictures of the solar system are never to scale. Draw the planets big enough to see, and they are far too close together; put them at their true distances, and they shrink to specks and run off the page.

Transcript

1. 0:00The Earth is about a hundred and fifty million kilometres from the Sun. A number that big is hard to picture. So let's shrink everything.
2. 0:18Make the Sun a football, twenty centimetres across. Then the Earth is a peppercorn, twenty-one big steps away.
3. 0:29And the Moon is a grain of sand, five and a half centimetres from the peppercorn. Every trip people have made in space fits in that gap.
4. 0:40Now walk out from the football. Mercury, a pinhead, at eight steps. Venus, a peppercorn, at fifteen. The Earth at twenty-one. Mars, a pinhead, at thirty-three.
5. 0:54All four rocky planets are within thirty-three steps. Now keep walking.
6. 1:02Jupiter, a grape, at a hundred and twelve steps. Saturn, a smaller grape, at two hundred and six.
7. 1:12Uranus, a pea, at four hundred and twelve. And Neptune, another pea, about six hundred and fifty steps from the football.
8. 1:22And the nearest star? Put the football in Madrid. The nearest star is another football in New York, about five thousand eight hundred kilometres away.
9. 1:34And between them, almost nothing at all.
10. 1:44Even light takes time to cross it. Sunlight takes about eight minutes to reach the Earth.
11. 1:56And about four hours to reach Neptune.
12. 2:08That's why pictures of the solar system are never to scale. Draw the planets big enough to see, and at their true distances they run off the page.
13. 2:26The solar system is huge, and almost all of it is empty space.