Paper 1 - Astrophysics

Question 1

What is a universe?

Answer 1

a large collection of billions of galaxies

Question 2

What is a galaxy?

Answer 2

a large collection of billions of stars

Question 3

What is our solar system located in?

Answer 3

The Milky Way galaxy

Question 4

why does gravitational field strength vary?

Answer 4

• GFS depends on the mass of the body creating the field and the distance from the body
• The larger the mass of the body, the stronger the magnetic field
• The closer to the body you are, the stronger the GFS is

Question 5

Why is GFS different on the Moon compared to on Earth?

Answer 5

The earth is more massive an object should weigh more on the moon

Question 6

How does gravitational force cause a body to orbit another body

Answer 6

The body that is less massive will orbit the body that is more massive as it has a weaker gravitational force

Question 7

Describe the differences in the orbits of comets, moons and planets.

Answer 7

• Comets orbit the sun but have very elliptical orbits with the sun at one focus
• Whereas, the orbits of moons and planets are only slightly elliptical

Question 8

How are stars classified according to their colour?

Answer 8

• The coolest stars are Red and emit most of their visible light at the lowest frequency
• The hottest stars are blue and emit more high frequency light than low-frequency light
• The order from hottest to coolest surface temperature is:
  Blue
  White
  Yellow
  Orange
  Red

Question 9

describe the evolution of stars of similar mass to the Sun

Answer 9

• Stars initially form from a cloud of dust and gas called a Nebula
• The gravitational force pulls the dust and gas together to form a protostar. The temperature rises, the star gets denser and nuclear fusion of hydrogen nuclei occurs to form helium nuclei.
• The energy produced expands the star which balances the gravitational force. The star is stable now and is called a Main Sequence Star
• Eventually, the hydrogen in the core runs out and the gravitational force is larger than the pressure of expansion. The star is compressed until it is dense and hot enough that the energy expands the outer layers of the star again and the star becomes a Red Giant. The star’s surface cools and becomes red
• The star becomes unstable and ejects its outer layer of dust and gas which leaves behind the hot, dense solid core - a white dwarf

Question 10

Stars initially form from a cloud of dust and gas called a Nebula
- The gravitational force pulls the dust and gas together to form a protostar. The temperature rises, the star gets denser and nuclear fusion of hydrogen nuclei occurs to form helium nuclei.
- The energy produced expands the star which balances the gravitational force of gravity. The star is stable now and is called a Main Sequence Star
- Eventually, the hydrogen in the core runs out and the gravitational force is larger than the pressure of expansion. The star is compressed until it is dense and hot enough that the energy expands the outer layers of the star again and the star becomes a Red Supergiant. The star’s surface cools and becomes red
- The star starts to glow brightly again as it undergoes more fusion. The balance between gravity and thermal expansion shifts and eventually the star explodes in a supernova
- The exploding superrnova throws outer layers of dust and gas into space, leaving a very dense core called a neutron star. If the star is massive enough, it will collapse and become a black hole