Comets and our journey to one
Paxi the alien tells us about comets and our spacecraft's journey to visit a comet called 67P.
What is a comet?
- It is an icy rock which flies around the sun. Scientists think the ice is frozen water and frozen gases.
- Some of their journey is near the sun where it is hot but some is very far away where space is very very cold. When it goes near the sun, the sun heats up the ice and the ice melts.
- In space, when ice melts it turns into gas.
- When the ice turns into gas, the gas forms a cloud around the icy rock.
- A comet can grow a long tail of gas and dust, which we can see from Earth.
- Although the tail can be millions of miles long, the dust particles in the tail are as big as grains of sand.
- Tricky words: 'Nucleus' means the icy rock centre of a comet. 'Coma' means the gas cloud around the comet. 'Sublimate' means to change from a solid into a gas. This is rare on Earth. Normally when you heat up solids, they change into a liquid, and when a liquid gets even hotter it turns into a gas.
It has taken people hundreds of years to discover things about comets. For over 30 years we have sent spacecraft into space to find out about comets.
Scientists think the comet 67P is just one of millions of comets. Another comet is called Halley's comet. It is famous. It is named after Edmond Halley who worked out that we would see it every 76 years (give or take a year). Edmond Halley was an astronomer, which is a scientist who studies natural objects in space. He discovered this in 1705 (39 years after the Great Fire of London).
Rosetta and Philae reach the comet
A quick look at how Rosetta flew 4 billion miles to reach the comet 67P.
Start at 57 seconds into the video to see the course of the journey.
After Rosetta had travelled for ten years, Rosetta arrived near the comet. The comet is between Mars and Jupiter. Rosetta slowed down and changed its path so that it was only a few miles above the nucleus.
After Rosetta took pictures of the comet and examined the gas in the coma, Rosetta released its lander (called Philae). When Philae landed on the comet, it used the screws in its feet to fix itself to the comet so it wouldn't fall off. Philae has now sent back the first pictures from a comet's surface. Philae is doing experiments to find out more about comets. It is trying to find out what materials are in the icy nucleus. The ice isn't just frozen water!
After Rosetta took pictures of the comet and examined the gas in the coma, Rosetta released its lander (called Philae). When Philae landed on the comet, it used the screws in its feet to fix itself to the comet so it wouldn't fall off. Philae has now sent back the first pictures from a comet's surface. Philae is doing experiments to find out more about comets. It is trying to find out what materials are in the icy nucleus. The ice isn't just frozen water!
Can you remember?
- Rosetta is a ___________
- Philae is a _____________ and it is the first to _________ on a comet.
- What is a comet? A comet is _____________________
- When the comet flies near the sun, the sun heats up _____ and it turns into ________.
- Comet 67P is shaped like a rubber ____.
- Rosetta and Philae travelled in space for ___ years.
- Rosetta met the comet between the planets ____ and _______.
- Philae's job is to find out what materials are in ____________.