The numbers
- How bright it gets
- Brighter than a whole galaxyFor short periods
- What it is
- The explosion of a star
- A famous one
- Seen in 1054, today the Crab Nebula
How it happens, step by step
The fire goes out
A very big star uses up the fuel in its heart, and with it the push that was holding up its weight.
The center collapses
Without that push gravity suddenly wins, and the heart of the star is crushed in a fraction of a second.
The collapse bounces
The center gets so dense it cannot be squeezed any further, and the wave of the collapse heads back outward.
The star explodes
That wave slams into the outer layers and hurls them into space. For days the star shines like a galaxy.
A cloud is left
The gas thrown out forms a spreading nebula, carrying around the heavy elements born in the explosion.
To get an idea
The heaviest elements are born in the explosion: the iron in our blood passed through there.
The supernovae seen in Europe in the 1500s proved that the sky is not unchanging.
Fun facts
These are not in the book: there was no room on paper.
The brightest one ever recorded was described by Chinese and Islamic astronomers.
The explosion seen in 1054 left the nebula we call the Crab, and such an event is rare.
Two supernovae seen in Europe in the 1500s disproved the idea of an unchanging sky.
None has been seen in our galaxy since 1604: they are rare events.
Amateur astronomers play an important part in being the first to discover supernovae.
Supernovae also help measure distances, because we know how bright they really are.
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
What is a supernova?
Question 2 of 5
How bright can it get?
Question 3 of 5
What happens to the star's heart?
Question 4 of 5
Why do supernovae matter to us?
Question 5 of 5
What is left after the explosion?
Riddles
For a few days I manage to shine brighter than billions of stars put together, and then I go out forever. I am the end of someone and the beginning of everything else. What am I?
Inside me the heavy things you are made of are born, and my wave scatters them around. Without me there would be no iron in your blood. What am I?
A thousand years ago some watchers saw me appear where there was nothing, and wrote me down in their records. Today in my place you find a cloud shaped like a crab. What am I?
Try it yourself
Look at Betelgeuse in the constellation Orion: it is one of the candidates to explode, although it could still take a very long time.
Think of the iron in your blood while you look at the sky: it was made inside a star and ended up here after an explosion.
The words
- supernova remnant
- The cloud of gas that spreads out after a star explodes.
Sources: Wikidata (Q3937), Wikipedia (Supernova).