Space Physics

Question 1

How is a star formed?

Answer 1

• form from a cloud of dust and gas called a nebula
• force of gravity pulls the dust and gas together to form a protostar
• as star gets denser, temp rises and more particles collide with each other
• when temp is high enough, hydrogen nuclei undergo nuclear fission to form helium nuclei
• this gives out huge amounts of energy which keeps core of star hot

Question 2

What is a red giant?

Answer 2

A small-medium star

Question 3

What is a red super giant?

Answer 3

A large star

Question 4

What is a main sequence star?

Answer 4

• when star enters a long stable period where outward pressure caused by nuclear fission that tries to expand the star balances the force of gravity pulling everything inwards
• typically lasts several billion years
• sun is in the middle of this stable period

Question 5

What happens to the star when the hydrogen runs out?

Answer 5

-it will swell into a red giant(if it’s a small star) or a red super giant (if it’s a large star)

Question 6

Why does a star become red?

Answer 6

• Because the surface cools
• fusion of helium and other elements occurs
• heavier elements (up to iron) are created in the core of the star

Question 7

What happens to a small-medium star such as the sun?

Answer 7

(Like the sun)

• becomes unstable and ejects its outer layer of dust and gas
• this leaves behind a hot, dense, solid core (a White Dwarf)

Question 8

What happens as a white dwarf cools down?

Answer 8

• it emits less and less energy

- when it no longer emits a significant amount, it is called a black dwarf

Question 9

What is at the centre of our solar system?

Answer 9

The sun which is orbited by eight planets and other objects

Question 10

What are the eight planets in the solar system?

Answer 10

Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto (dwarf planet)

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Question 11

What is a planet?

Answer 11

Large objects that orbits a star

-there are 8 in our solar system

Question 12

What is a Dwarf planet?

Answer 12

Planet-like objects that orbit stars but do not identify as planets

Question 13

What is a moon?

Answer 13

• they orbit planets

- a type of natural satellite (not man made)

Question 14

What is an artificial satellite?

Answer 14

• satellites that humans have built that are sent into space

- they generally orbit the Earth

Question 15

Which galaxy are we a tiny part of?

Answer 15

The Milky Way Galaxy

Question 16

What is the Milky Way Galaxy?

Answer 16

A massive collection of billions of stars that are all held together by gravity

Question 17

What force creates orbits?

Answer 17

-gravitational force between the planet and sun or planet and its satellites

Question 18

What does the size of the orbit depend on?

Answer 18

The objects speed

The stronger the force, the faster the orbiting object needs to travel at to remain in orbit

Question 19

Why does the universe seem to be getting bigger?

Answer 19

All it’s galaxies seem to be moving away from each other. We know this as when we look at light from most distant galaxies, we find that the wavelength has increased (red shift)

Question 20

Why do scientists believe there was a bang?

Answer 20

• all galaxies moving away from each other at great speed which was caused by big explosion (Big Bang)
• all matter in universe occupied a very small space which was very dense and very hot
• then it ‘exploded’ and space started to expand