Astrophysics
4 marks · EasyStars can be classified by their colour and temperature. The diagram below shows stars of different classes.
| Class | Surface temperature (K) | Colour |
|---|---|---|
| O | >33,000 | Blue |
| G | 6,000–5,200 | Yellow |
| M | 2,000–3,700 | Red |
Which class does the Sun belong to? State the reason for your answer.
Describe how the colour of a star tells us about its surface temperature.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
Show answer
(a) Class G. Because the Sun's surface temperature is about 6000 K and it is yellow.
(b) Hot stars are blue, medium temperature stars (like the Sun) are yellow, and cooler stars are red.
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · Gives the correct class: 'G'.
B1 (a) · 1 mark · Correct reason: refers to Sun's temperature or colour.
B1 (b) · 2 marks · Correctly relates colour to temperature for blue/hot, yellow/medium, and red/cool.
Worked solution
(a) The Sun is a class G star because its surface temperature is about 6000 K and it appears yellow.
(b) The colour of a star tells us its surface temperature: blue stars are the hottest, yellow stars are medium, and red stars are the coolest.