Astrophysics IGCSE Edexel

Definition of universe

A large collection of billion of galaxies

Definition for galaxy

A large collection of billions of stars

Stars may be a part of____

Planetary system

Definition of weight

The force acting on an object due to gravitational attraction

What is the force of weight responsible for

Object staying firmly on the ground

Objects always fall into the ground

Satellites being kept in orbit

The greater the mass of the planet____

The greater its gravitational field strength

The value of g varies with___

The distance from a planet

What does planet orbit

Sun

What does moon orbit

Planet

What does comet orbit

Sun

All planets orbit in__

Same plane

All planets travel in

Same direction

However all planets orbit at

Different distances from the Sun and different speeds

The planets furthest from the Sun take the ______amount of time to orbit the Sun

Longest

The planets closest to the Sun take the_____ Time to orbit the Sun

Shortest

Moons orbit planets in a___ path

Circular

The orbits of comets are

Very elliptical / hyperbolic

The speed of the comet_____ is there distance from the Sun changes

Changes significantly

The comet approaches the Sun it's speed_____

Increases

As the comet moves further away from the Sun it speed____

Decreases

Average orbital speed=

2πr/T

What does T stand for in the average orbital speed equation

Orbital period

Orbital period definition

The time taken for an object to complete one orbit

What does the star’s temperature depend on

Colour

How hot are the blue stars

30000k

How hot are the light blue stars

20000k

How hot are the white stars

10000k

How hot are the yellow stars

6000k

How hot are the Orange stars

4000k

How hot are the red stars

3000k

Astronomical objects cool as they ____

expand

Astronomical objects heat up as they____

contract

What is the order of the life cycle of solar mass stars

Stellar nebula, protostar, main sequence star, red giant, planetary nebula, wide dwarf

What is a nebula

a giant interstellar cloud of gas and dust

How was the protostar formed

The force of gravity within a nebula pulls the particles closer together until a hot bowl of gas forms

What happens once protostar becomes hot enough

Nuclear fusion reactions will begin within its core and the main sequence star is formed

During the main sequence the star is in____

Equilibrium

How does red giant form

The hydrogen causing fusion reactions in the star will begin to run out so the fusion reactions in the cored will start to die down and the start will begin to fuse helium which causes the outer part of the start to expand

How does the red giant become a white dwarf

Once the helium fusion reactions have finished the star collapses and becomes a white dwarf

What happens after the main sequence of larger stars

Red super giant, supernova, and neutron star/ Black hole

Why does the supernova occur

Once fusion reactions inside red super giant cannot continue the core of the star will collapse suddenly and cause gigantic explosion

How's the neutron star formed

At the centre of the supernova explosion a dense body called a neutron star will form

Why is there a possibility of black hole occurring

The neutron star will continue to collapse under the force of gravity forming a black hole

What is a black hole

Extremely dense point in space not even light can escape