8. Space Physics Flashcards
How many stars are in our solar system?
One - the sun
What are natural satellites?
The moons that orbit planets
What is our solar system a small part of?
The Milky Way galaxy
Why is Pluto no longer classified as a planet?
- other objects started to orbit near Pluto with masses similar to pluto (Kuipur belt)
- as well as orbiting, a planet has to ‘clear the neighbourhood around it’s orbit’ which pluto has not done
What keeps the planets in their circular orbit around the sun?
- gravity
* don’t fall as they’re moving very quickly - centripetal force
What is a centripetal force?
When an object moves in a circular path and there is a resultant force acting towards the centre of the circle
When does the size of the centripetal force increase?
- when the MASS or SPEED of the object increases (more MOMENTUM = bigger force to change it)
- the radius decreases - a tighter turn needs a bigger force
What are some examples of forces that can provide the centripetal force?
- friction (e.g. a car on a roundabout)
* gravity (e.g. a planet)
What does it mean for an object’s velocity and direction if it is travelling in a circle?
- it’s constantly changing direction so it is constantly accelerating
- this means it’s constantly changing velocity (but not changing speed)
How was the solar system formed?
- 6 billion years ago - old star exploded (supernova) and clouds of gas and dust called nebula formed
- the nebula was pulled together due to gravity and formed planets
- if the planets were big, dense and hot enough then a star would have formed and fusion would’ve occurred
Are all stars the same?
They form in the same way but there is a huge range of masses
How are stars formed?
Gravity pulls together a gas nebula which heats up until fusion starts
What is the life cycle of a star that ends up as a black dwarf?
- nebula
- protostar
- main sequence star
- red giant
- white dwarf
- black dwarf
What is the life cycle of a star that ends up as a neutron star?
- nebula
- protostar
- main sequence star
- red super giant
- supernova
- neutron star
What is the life cycle of a star that ends up as a black hole?
- nebula
- protostar
- main sequence star
- red super giant
- black hole
What size are red giants?
About the same size as the sun
What size are super red giants?
Much bigger than the sun
What is it called when a star first begins to shine?
A protostar
What happens when a protostar has contracted enough so that it is very hot and dense?
Nuclear fusion starts and releases energy to form a main sequence star
What type of star is the sun?
A main sequence star