P16 Space Flashcards
What are comets?
• What shape are their orbits?
Frozen rocks.
• Elliptical shape (ovalish)
What’s a meteor?
Small bits of rock that burn up when they enter the earth’s atmosphere. (Shooting star)
How did the sun form?
By clouds of dust and gas pulled together by gravitational attraction.
What temperature is the ‘habitable’ zone?
What does it mean?
1-100 degrees C
Liquid water can exist there.
What are stars formed from?
Gas and dust.
What is a protostar?
Is a concentration of gas and dust that becomes hot enough to cause nuclear fusion.
How does a protostar form?
- Particles of dust and gas are pulled together by their own gravitational attraction - particles speed up.
- Clouds merge
How does a star form?
- Protostar
- As it becomes denser the particles speed up more and the temp increases - energy transfer from GP energy to thermal.
- If becomes hot enough, nuclei of the hydrogen atoms fuse together forming helium nuclei. Energy released.
Why is the sun stable?
Because the gravitational forces acting inwards balance the force of nuclear fusion in the core acting outwards.
Why is energy released inside a star?
Because of nuclear fusion.
When does a star become unstable? (Stats smaller then the sun or the same size)
What is the star now called?
It runs out of hydrogen nuclei. Reaches the end of its main-sequence stage it’s core collapses and it starts to swell.
A red giant.
How are heavier elements formed? (Nuclei larger than iron nuclei)
In the core of a red giant, helium and other light elements fuse.
What happens to stars much bigger than the sun after they finish their main-sequence stage?
- They swell out and become red supergiants.
- They collapse
- in collapse, the matter surrounding the stars core compresses the core more and more, the compression suddenly reversed in a supernova
- the explosion compresses the core into a neutron star.
- If enough mass it turns into a black hole.
Stages of a star the same size or smaller then the sun?
Protostar ~ main-sequence star ~ red giant ~ white dwarf ~ black dwarf
Stages of a star much more massive than the sun?
Protostar ~ main-sequence star ~ red supergiant ~ supernova ~ neutron star (or black hole if enough mass)
An example of a:
- Natural satellite
- Artificial satellite
- the moon
- a satellite
What shape is the earth’s orbit?
Circular.
What keeps a planet moving along its orbit?
The force of gravity between a planet and the sun