Chapter 3 Cosmology

Question 1

What is the theory behind the Doppler Shift

Answer 1

The doppler shift is where the wavelengths of light waves from a star moving towards the Earth are shorter than they would be from a star moving away from the Earth

Question 2

What are the two types of Doppler Shifts

Answer 2

Red Shift & Blue Shift

Question 3

What is a Red Shift

Answer 3

A red shift is where the wavelengths of light are longer due to the star emitting them moving away from the Earth, they have a longer wavelength and a lower frequency.

Question 4

Why is this effect called the Red Shift

Answer 4

This effect is known as the Red Shift as when putting the light through spectroscopy the line spectrum formed has a shift towards the red end of the visible light spectrum

Question 5

What is a Blue Shift

Answer 5

A blue shift is where the wavelengths of light are shorter due to the star emitting them moving away from the Earth, they have a shorter wavelength and a higher frequency.

Question 6

Why is this effect called Blue Shift

Answer 6

This effect is known as the Blue Shift as when putting the light through spectroscopy the line spectrum formed has a shift towards the Blue end of the visible light spectrum

Question 7

What does Hubble’s Law state

Answer 7

That galaxies are receding from us, each moving at speed v, that is directly proportional to the distance, d.

Question 8

What is the equation for Hubble’s Law

Answer 8

v = Hd, where v is the velocity, H is Hubble’s Constant and d is the distance

Question 9

What is dark energy

Answer 9

Dark energy is energy which is currently unknown, like dark matter it is used to explain the apparent loss of energy since the Big Bang, as well as to explain the mass of specific universes where the mass of the bodies inside of them does not equal the mass calculated from their gravitational pull.

Question 10

What is a Quasar

Answer 10

A Quasar is among the oldest and most distant objects in the universe, they are made up of fast moving clouds of gases and jets of matter being ejected.

Question 11

What are the characteristics of a Quasar

Answer 11

Very powerful light output, much greater than the light output of a star
Relatively small size, not much larger than a solar system
Large red shift which indicated the fact that they are usually between 5000 and 10000 light years away from the Earth

Question 12

How can Quasars be observed?

Answer 12

Quasars can be observed through optical and radio telescopes

Question 13

How are Quasars formed

Answer 13

Quasars are formed from active Supermassive Black Holes, and it is theorised when looking at them, we are in fact looking at a supermassive black hole in action.

Question 14

What is an Exoplanet

Answer 14

an exoplanet is a planet which orbits a star outside our Solar System

Question 15

What are the main method of detecting exoplanets

Answer 15

Radial Velocity Method & Transit Method

Question 16

What is the Radial Velocity Method of detecting Exoplanets

Answer 16

The Radial Velocity Method involves observing the line spectrum of the light from the star in an attempt to detect a periodic doppler shift in the wavelength of light from the star

Question 17

Why would a periodic doppler shift occur from the wavelengths of light from a star

Answer 17

A periodic doppler shift can occur in the wavelengths of light from a star when a planet or other celestial body moves around it causing the common center of mass to shift and hence cause the star to move away or towards the Earth.

Question 18

What is the Transit Method of detecting exoplanets

Answer 18

The transit method involves measuring and recording the intensity of the light from the star, if there is a regular dip in the intensity of the light, there is a high chance that there is something orbiting that star, with the dip in intensity being proportional to the size of the exoplanet.