The numbers
- Where it begins and ends
- From the orbit of Neptune outward30 to 50
- Compared with the asteroid belt
- 20timeswider, and much more massive
- What it is made of
- Ices of water, methane and ammonia
- How many are known
- 1,000objectsbut there could be many more
To get an idea
Out there the Sun is a dot and gives almost no warmth: water has stayed frozen for billions of years.
More than a thousand objects are known, but the big ones could number a hundred thousand.
Fun facts
These are not in the book: there was no room on paper.
The objects wider than about sixty miles are thought to number more than a hundred thousand.
Many short-period comets come from here, knocked off course and fallen toward the Sun.
The objects in the belt are so dark and far away that only big telescopes can discover them.
Some scientists count Eris as part of the scattered disk, an even farther region.
These bodies are material left over from the formation of the Solar System, still as it was.
Test yourself
The first question is the one printed under the QR code, with the answer the book did not give. The other four only exist here.
Question 1 of 5★ is the one from your book
Where does the Kuiper Belt begin?
Question 2 of 5
What is it made of?
Question 3 of 5
Who is its most famous resident?
Question 4 of 5
How much wider is it than the asteroid belt?
Question 5 of 5
What does an object falling toward the Sun become?
Riddles
I begin where the last planet ends and I am made of ice, not rocks. My most famous resident lost the title of planet because of me. What am I?
For billions of years I have kept the leftover bricks of a building project, because nobody ever comes by my way to stir things up. What am I?
Every now and then one of my residents gets pushed down toward the warmth, melts a little and grows a glowing tail. Then you change its name. What am I?
Try it yourself
Look for a close-up photo of Pluto and find the big pale plain shaped like a heart: it is ice, not rock.
Draw the Solar System to scale on a roll of paper: after the last planet you will need as much paper again as you have already used.
The words
- trans-Neptunian object
- A body that goes around the Sun farther out than Neptune.
- scattered disk
- An even farther region, with very stretched and tilted orbits.
Sources: Wikidata (Q13780), Wikipedia (Fascia di Kuiper).