Space Flashcards
(20 cards)
What is in our solar system?
The sun, planets, dwarf planets, moons, the asteroid belt and comets.
What are the planets in our solar system?
There are 8 planets in our solar system: mercury, venus, earth mars, jupiter, saturn, uranus and neptune.
How are stars formed?
Stars begin as a cloud of dust and gas (a nebula), these are then pulled together by gravity and as they gradually get faster they collide more often causing the gas to warm up and begin to glow, this is a protostar. As the protostar gets more dense, there are more collisions and it gets even hotter eventually hot enough to fuse and form helium. This state is called a main sequence star.
Why do stars stay in the main sequence stage?
In a main sequence star the inward force of gravity and the radiation emitted from the fusion in the core are balanced. The forces are in equilibrium
Why do we have heavy elements above iron on earth?
Elements such as uranium and iron are heavy elements and so are produced in supernova explosions.
What will eventually happen to a star?
A star will eventually run out of hydrogen to fuse and it’s core will collapse and the outer layers will swell and cool - causing a red giant to form. In a red giant light elements like helium fuse to form heavier elements. When there are no light elements left, fusion stops and there is no more radiation leading to a white dwarf being formed. Eventually a white dwarf dims and becomes a black dwarf
What happens to much bigger stars?
Stars much bigger form red supergiants, due to their much larger size when these stars collapse more violently and a supernova explosion occurs. In a supernova explosion elements heavier than iron are formed. This explosion compresses into a neutron star ( a star made of neutrons ) and if the star was massive enough it forms a black hole.
What is a planet?
A planet orbits a star and has enough gravity to become spherical and finally sweeps out it’s own orbital path.
What is a moon?
A moon orbits a planet. Our moon is a natural satellite.
What is a satellite?
A satellite is a man-made moon.
What provides the force that allows planet and moons to maintain circular orbit?
Gravity, it is an example of a centripetal force as it acts towards the centre of a circle.
Describe a circular orbit
An object orbits another at a constant speed. Its direction is constantly changing so its velocity is changing . Therefore we say the object is accelerating towards the centre of
the circle.
What happens to an object in orbit if it’s speed changes?
If an object in orbit slows down than it will fall into lower orbit until it crashes to the surface. If an object speeds up it will rise into a higher orbit until it eventually escapes into space.
What is red-shift?
Red-shift is when light is stretched if a star or galaxy is moving away from us. This causes the light to move towards the red side of the light spectrum thus we call it red shift.
What is red-shift evidence for?
The faster a star or galaxy is moving away from us the greater the effect of red-shift. Since galaxies further away from us have a higher red-shift than those closer we can infer they are moving away at an increasingly fast rate. This provides evidence for the big bang as it shows the universe is expanding.
What is blue-shift?
If a star or galaxy is moving towards us it moves to the blue side of the light spectrum so we call this blue-shift.
What does the big bang theory suggest?
The big bang theory is the idea that the universe originated from an extremely hot and dense point.
What other evidence is there for the big bang?
Cosmic microwave background radiation (CMBR)
What other theories were there for the universe?
The steady state theory suggested that the universe was slowly expanding and had always existed. There is more evidence for the big bang so it is more widely accepted.
What will happen to our universe?
Depending on the total mass of our universe one of two things could happen: the big yawn - the universe is less dense so will continue expanding until the stars die out or the big crunch - universe is more dense so will stop expanding and collapse.
