5.5 - Astrophysics and Cosmology

Question 1

Define Planet

Answer 1

Large objects which orbit a star. where no nuclear fusion occurs and the object has cleared its orbit of other objects.

Question 2

Define a Planetary Satellite

Answer 2

Objects that orbit a planet e.g Moons, artificial satellites

Question 3

Define a Comet

Answer 3

Small, irregularly sized balls of rock, dust and ice. They orbit the sun in eccentric elliptical orbits

Question 4

Define a Solar system

Answer 4

The systems containing stars and orbiting objects like plannets.

Question 5

Define a Galaxy

Answer 5

Collection of stars, dust and gas. each galaxy contains about 100 billion stars and are held together by gravitational attraction

Question 6

Define Universe

Answer 6

All existing matter and space in which it is contained

Question 7

Describe the process of forming a star

Answer 7

A collection of dust and gas called a nebula is pulled together by gravitational attraction to form clouds.

As they come closer, the gas loses GPE which is converted to kinetic energy, increasing the temp of gas.

Eventually, the gas has high enough kinetic energy that nuclear fusion starts to occur, producing photons which when absorbed by the outer layers of gas exerts a radiation pressure which keeps the star in an equilibrium state for billions of years.