Space Flashcards
What is the relationship between mass and gravity?
If mass is doubles, the force will double.
Directly proportional.
What is the relationship between distance and gravity?
If distance is doubled, gravity is quartered.
This is called the inverse square law.
What is a light year?
The distance traveled by light in one year.
How many kilometres is in a light year?
9.47 x 10^12km
This is calculated by speed of light in km/s x no. of seconds in a year
What is the nearest star to our galaxy?
Alpha Centauri, at 4.3 light years
What are nebulae?
Clouds of gas, mostly hydrogen and helium
How do stars form?
Clouds of gas (nebulae) mostly consisting of hydrogen and helium are pulled together by gravity. As the gas forms into a ball the temperature rises and the “infant” star begins to give out infrared radiation.
Temperature and pressure in the centre builds up until it becomes possible for hydrogen nuclei to fuse together to make helium. This is called nuclear fusion.
The radiation given off by nuclear fusion pushes outwards against the force of gravity, preventing any further collapse of the star. Once formed, a star will undergo fusion until it runs out of suitable fuel material.
What is the relationship between radiation pressure and gravitational force in a star throughout most of its life?
Radiation pressure = Gravitational force
What ways can a star die?
Most die a peaceful death, but if it has a large mass it will become a red supergiant until the central core collapses to produce a shockwave which makes the outer layers explode - known as a supernova. Two things may then happen:
- The core continues to collapse under its own gravity and forms a neutron star. These are very small with an enormous density. Rotating neutron stars emit radio signals instead of visible light and are known as pulsars.
- If the star is very massive it may continue to collapse until all its mass it’s attracted to a single point. This is called a black hole.
What is a black hole?
A great amount of matter packed into a very small area - with a gravitational field so strong that nothing, not even light can escape.
What are the stages a typical star goes through throughout its lifespan?
Nebula
Protostar
Main sequence
Red giant
Planetary nebula
White dwarf
Black dwarf
How did red shift help support the Big Bang theory?
An astronomer named Hubble discovered that the light coming from different stars had shifted from where it should be, and was closer to the red side of the spectrum than normal.
This could only mean that stars and galaxies were moving away from us, i.e the universe is expanding.
This supported the idea that all material in the universe was once much closer together. The Big Bang Theory proposes that the universe started when this material exploded, and material is still moving as a result of the explosion.
