Space Physics

Question 1

Anything that orbits a planet is called a satellite
Explain the 2 different types

Answer 1

• natural satellite (moon) aren’t man made
• artificial satellites are man made (communication satellites, orbiting telescopes etc)

Question 2

Order of the planets in the solar system

Answer 2

Closest to the sun:
Mercury
Venus
Earth
Mats
Jupiter
Saturn
Uranus
Neptune

Question 3

All planets orbit the sun in a slight elliptical orbit, what does this mean

Answer 3

The path isn’t a perfect circle
(Slightly squashed)

Question 4

What are the differences between asteroids and comets

Answer 4

Asteroids:
-made of mostly rock and metal
-found in the asteroid belt (between mars and Jupiter)

Comets:
-made of ice and dust
-orbit the sun in very elliptical orbits

Question 5

What is a galaxy (like the Milky Way)

Answer 5

• Collections of starts with their own solar systems
• the force holding all the stars together is gravity

Question 6

What is the universe

Answer 6

• scatterd with galaxies and lots of empty space

Question 7

What is a solar system

Answer 7

• consisted of central star with planets orbiting around it

Question 8

What is an orbit

Answer 8

The curves path of one celestial object or spacecraft around another celestial object

Question 9

How do objects orbit planets

Answer 9

Newton’s first law:
An object traveling at a certain velocity will continue to travel at that velocity, unless acted upon by a resultant force

• the Earth is large and has a strong gravitational pull on satellites around it
  (An attractive force towards the Earth)
  This acts as the resultant force
• because the moon is quite big and travels at a high speed, it has lot of momentum in its forward direction
• so the gravitational force isn’t fully strong enough to pull it towards the Earth, it can only change its direction slightly
• because the Earth always has this gravitational force, it’s always changing the moon’s direction
  So it’s always orbiting around the Earth
• because velocity is measured by both speed and direction, the moon’s velocity is constantly changing
• any change of velocity causes acceleration (based on its equation), so the moon is always accelerating even though it’s not getting faster or slower

Question 10

Describe what is meant by red shift, link this to the Big Bang theory

Answer 10

• the further away a wave source is, the higher its speed of travel and wave length, and the lower it’s frequency
• on the wave length absorption spectrum, things with a higher wave length are on the red side. Light waves from distant galaxies are shifted toward the red side of the spectrum (left) compared to the light coming from the sun which is more to the right.
• So, light waves from other galaxies are getting stretched as they reach towards Earth due to the long distance they have to travel.
  This shows how galaxies are moving further and further away from us proving that space and the universe is expanding.
  (The space between us and distant galaxies is expanding, making us further away from galaxies)

Question 11

What is the Big Bang theory

Answer 11

• all the matter in the universe occupied a small space which and was extremely dense and hot
• all of a sudden it exploded and space started to expand, it’s still expanding to this day

Question 12

Describe the life cycle of a star

Answer 12

1) it starts of with a cloud of dust and gas (usually hydrogen and helium) pulled together by gravity, called a nebula
2) gravitational force pulls in more and more dust and gas until it is dense and spirals into a protostar
3) the gravitational energy is converted into heat energy. When the protostar has a high enough temperature and pressure the hydrogen nuclei undergo nuclear fusion in the core, to form a helium nuclei. This gives out massive amounts of heat and light
A main sequence star is born.
4) the star enters a long stable period for millions of years. Its outwards pressure from the heat created by nuclear fusion is balanced by the inwards pressure of gravity, keeping the star stable.
( the sun is in this stage)
5) eventually the hydrogen will run out and the pressure of gravity will take over.

Red giant:
- the star then expands into a red giant, shedding out layers of gas which exposes the core as a white dwarf. Once it cools and emits all its energy, it becomes a black dwarf

Red super giant:
- a larger star will swell to become a red super giant, by expanding and contracting several times, the helium nuclei fuse to form carbon followed by further fusion forming heavier elements like nitrogen and oxygen, making it shine bright again
The outer layers then blast away as a super nova emitting the elements into the universe. This leave a dense core called a neutron star, if big enough this will collapse into a black hole