New
New
Year 11
OCR
Higher
Observing the universe
I can describe what redshift is and how it is measured.
New
New
Year 11
OCR
Higher
Observing the universe
I can describe what redshift is and how it is measured.
These resources will be removed by end of Summer Term 2025.
Switch to our new teaching resources now - designed by teachers and leading subject experts, and tested in classrooms.
Lesson details
Key learning points
- Telescopes extended what was visible after their invention in the seventeenth century.
- Images detected by telescopes in space are not distorted by effects of the Earth’s atmosphere.
- A galaxy is a group of hundreds of billions of stars, and there are many galaxies spread across the universe.
- A visible spectrum of light emitted from stars or galaxies shows dark lines of frequencies of light.
- Red shift is the movement of hydrogen lines towards the red end of the visible spectrum.
Keywords
Space telescope - is a telescope positioned in space to avoid atmospheric interference and observe parts of the spectrum which cannot reach the Earth’s surface
Galaxy - is a collection of many millions or billions of stars held together by gravitational forces
Redshift - is the increase in the wavelength of light (and decrease in its frequency) cause by the movement of a star or galaxy away from us
Common misconception
Stars twinkle (change brightness rapidly).
Explore the ideas that Earth’s atmosphere is made of moving air that refracts light from stars in changing directions to distort the light coming from stars.
This lesson goes beyond the syllabus in places in order to provide pupils with an understanding of redshift, which is necessary for understanding the big bang theory for the origin of the universe.
Teacher tip
Licence
This content is © Oak National Academy Limited (2025), licensed on
Open Government Licence version 3.0
except where otherwise stated. See Oak's terms & conditions (Collection 2).Lesson video
Loading...
Starter quiz
Download starter quiz
6 Questions
Q1.
A star fuses hydrogen in its core. It is stable for long periods of time (often billions of years).
Q2.
What type of star will the Sun change into next, after it stops fusing hydrogen in its core (in about 5 000 000 000 years)?
red dwarf star
white dwarf star
white dwarf star
Q3.
Sort the following stages of a star's life, for a star similar in size to the Sun, into the order in which they take place.
Q4.
What is a giant exploding star called?
Q5.
What is a neutron star that is formed from the core of a supernova?
a very large and hot white dwarf star
an incredibly hot ball of plasma and gas
an incredibly dense ball of atoms
Q6.
What is a black hole that is formed from the core of a particularly large supernova?
the core of a massive star compressed to a few thousand metres across
the core of a massive star compressed to a few hundred metres across
the core of a massive star compressed to a few metres across
Exit quiz
Download exit quiz
6 Questions
Q1.
Which of the following optical instruments can improve what we can see in space?
microscopes
stethoscopes
Q2.
What makes a star appear to twinkle in the night sky?
clouds
gases around the star
nebulae in space
Q3.
What are the advantages of using a space telescope compared to a telescope on Earth?
It is very expensive to construct and launch.
It is smaller in size.
Q4.
How do Messier objects that can be seen with a telescope differ in appearance from stars?
They are much brighter.
They have distinct colours.
Their brightness varies in a regular pattern.
Q5.
What are absorption lines in a spectrum of light from a star?
coloured lines that add together to make a visible spectrum
black lines on a visible spectrum caused by a telescope
black lines on a visible spectrum caused by air in Earth's atmosphere
Q6.
What observation shows that redshift has occurred and that the wavelength of light from a distance galaxy has increased?
there is less red light in the visible spectrum of the galaxy
there is more red light in the visible spectrum of the galaxy
absorption lines in its spectrum have higher than expected frequencies