Space physics

Describe how stars are formed.

Enough gas is pulled together by gravitational attraction.

Explain why the Sun will not go through the supernova stage but the star Mira will.

Only very massive stars become supernova. Mira is large enough but sun is too small.

Why do telescopes in space give better images than telescopes on the Earth?

No clouds in the way.

Compared to the light from the Sun, the light from the distant galaxy has moved towards the red end of the spectrum. What name is given to this effect?

Red shift.

State one other piece of evidence that supports the Big Bang theory of the formation of the Universe.

Cosmic microwave background radiation.

Scientists cannot give the exact number of years a star will be in the 'main sequence' period. Suggest why.

Insufficient evidence. Don't know exact amount of hydrogen in star.

State two factors that determine the size of the centripetal (gravitational) force on the satellite.

Mass and speed of satellite.

Why is the rate of nuclear fusion in a large star faster than in a small star?

Larger stars have a shorter 'main sequence' period so they must have the faster rate of nuclear fusion since they use up hydrogen at a faster rate.

The Universe now contains a large variety of different elements.
Describe how this happened.

Fusion takes place within stars. Hydrogen formed into helium. Fusion continued and formed larger elements. Elements heavier than iron were formed during supernova.

Describe what happens to a star much bigger than the Sun, once the star reaches the end of the 'main sequence' period of its life cycle.

Star runs out of hydrogen and expands then cools. A red supergiant explodes as a supernova. Core shrinks. Becomes a neutron star.

Explain how red shift supports the Big Bang theory.

The furthest galaxies show the biggest red shift so they are moving the fastest so universe is expanding. Universe started from an initial point.

Why was the discovery of cosmic microwave background radiation important?

Provided more evidence to support the 'Big Bang' theory.

State one difference between an ultraviolet wave and a visible light wave.

Ultraviolet has higher frequency.

What information can scientists find out about a galaxy when they measure the size of the red-shift the galaxy produces?

Distance. Speed galaxy is moving.

Explain how atoms of the element (He) are formed in a star.

Fusion of hydrogen atoms.

How is the wavelength of CMBR likely to change, if at all, over the next billion years?

Increase. Universe will continue to expand.

Explain the difference between a protostar and a main sequence star.

Protostar has lower temperature. as fusion reactions haven't started.

The light arriving from distant galaxies provides scientists with evidence to support the 'Big Bang' theory. Explain how.

Light shows a red shift so galaxies are moving away.

Explain what the conditions need to be for a star to remain stable.

Gravitational forces balanced by radiation pressure.

What is red-shift ?

Wavelength increase.

Describe what will happen to a star, originally much more massive than the Sun, after it reaches its red giant stage.

Explode as supernova. Outer layer thrown into space.

Explain how, and when, atoms of different elements may be distributed throughout the Universe.

Supernova. When stars die.

Hubble's constant, H0, represents:

the ratio of the speed at which the galaxy is moving away from the Earth to its distance from the Earth

Hubble's Constant equation

v = H0 x d ( In the equation,

v is the velocity of a receding galaxy, d

is the distance to the galaxy and H0 is the Hubble's constant.

Hubble's constant is approximately

2.2 × 10–18 per second (where distance is in meters)