Space

Question 1

What are the main differences between the planets of our solar system?

Answer 1

The orbits are shortest closest to the sun and the temperatures are the highest, the last 4 planets are gas giants.

Question 2

What is the difference between comets, asteroids, natural satellites and artificial satellites?

Answer 2

Moons are natural satellites, humans make artificial satellites that take either close, fast polar orbits or long, slower, geostationary orbits. Asteroids have highly elliptical orbits that may take millions of years to complete and they are made of metals and rocky materials. Comets are made of rocky material, dust and ice and when they go near the sun they vaporise and turn into gas and develop a distinctive tail.

Question 3

What is necessary for a planet to form?

Answer 3

It’s gravity must be strong enough to make it spherical and attract smaller local objects.

Question 4

What is the simple equation for nuclear fission in stars?

Answer 4

2/1H +3/1H - 4/2He +1/0n

Question 5

Explain in full the life cycle of a star.

Answer 5

1. A nebulla (cloud of gas and dust) collapses under its own gravity, and its gravitational potential energy is transferred to its kinetic store so it becomes denser and rotates rapidly. This rotation leads more collisions between particles so energy is transferred to the particle’s internal store.
2. It is now a hot, dense protostar. A star is formed when nuclear fission begins, hydrogen nuclei join to form helium nuclei and energy is transferred by radiation to expand the star. This releases energy which keeps the core hot.
3. It is now a main sequence star as the radiation expanding the star and gravitational attraction collapsing it counteract each other.
4. When all the hydrogen has been used up in the fusion process, larger nuclei begin to form and the star may expand to become a red giant.
5. Now stars like the Sun does no more nuclear reactions, contracts under gravity and increases in temperature and becomes a white dwarf. Then it fades and changes colour as it cools, it will end as a black dwarf. Stars with much greater masses than the sun will go on making nuclear reactions, getting hotter and expanding until it explodes as a supernova.
6. After a supernovae, depending on its original mass a star will become a black hole or neutron star.