First look
The idea, in plain words
Shrink the Sun to the size of a football and put it on the centre spot of a pitch.
On that scale the Earth is a peppercorn 2 mm wide, about 24 metres away. Jupiter is a large marble 120 metres off, out beyond the stands. Neptune is a pea 700 metres away, somewhere in the streets around the ground.
Everything in between is empty.
Now for the part that is hard to believe. The next football, the nearest star, is not in the next town, or even the next country. On this scale it is about 6,300 km away, roughly as far as London is from Chicago.
That emptiness is what the 3D view on this site is built to show. When you fly from the Earth to the Moon and it takes a moment, then fly on to Neptune and watch the Sun shrink to a bright star, you are seeing the real spacing. Nothing has been squeezed to fit.
Go deeper
That was the idea. The same subject is written again below for readers who want more, each on a page of its own.
Words used here
- Power of ten
- A step of ten times bigger or ten times smaller, the only practical way to count the sizes of things in space.
- Astronomical unit
- The average distance between the Earth and the Sun, used as the ruler inside the Solar System.
- Light year
- The distance light travels in one year, about 9.46 million million km.
- Oort cloud
- A vast, thin shell of icy bodies thought to surround the Solar System out to tens of thousands of au.
- Heliosphere
- The bubble that the solar wind blows in the thin gas between the stars.
Worth knowing
Voyager 1, launched in 1977, is the most distant thing people have made. It is about one light day away, after nearly fifty years of flight. The nearest star is 1,550 times further still.
Worked out from measurements. NASA, where the Voyagers are now
The Moon averages 384,400 km away, but swings between about 363,300 and 405,500 km.
The Sun is 109 Earths wide, and about 1.3 million Earths would fit inside it.
Worked out from measurements. NASA NSSDC Sun fact sheet
Where this comes from
The words are written for this site. The pictures are drawn by the page from the figures in the lesson, and each one says underneath what it is based on.