P 7 20 Questions

Traffic Light Quiz

Rules

• Everyone should reveal their answer at the same time

• Count down: 3, 2, 1, show!

1. The parallax angle of a star is..

twice the angle moved against the background of distant stars in 6 months

half the angle moved against the background of distant stars in 6 months

the angle moved against the background of distant stars in 6 months

2. A smaller parallax angle means..

The star is further away

The star is closer

The star is not as bright

3. What is a parsec?

The distance to a star with a parallax angle of one degree of arc

The distance to a star with a parallax angle of one minute of arc

The distance to a star with a parallax angle of one second of arc

4. What is a light year?

The distance travelled by light in a year

The time it takes light to travel one parsec

The time it takes light to travel around the Sun

5. What is the typical distance between adjacent stars?

A few million km

A few parsecs

A few thousand parsecs

6. The intrinsic brightness (luminosity) of a star depends on…

its distance from us and its colour

its size and its mass

its temperature and its size

7. What is a Cepheid variable?

A star with brightness that changes periodically

A galaxy that contains a wide variety of stars

A star that is changing from a red giant to a white dwarf

8. What does the period of a Cepheid variable depend on?

How far the star is away

How old the star is

How bright the star is

9. What is a galaxy?

A cluster of hundreds of stars

A cluster of billions of stars

A group of millions of planets

10. What did most astronomers believe at the start of the 20th century?

Our galaxy is the only one in the Universe

Our Sun is the only star in our galaxy

Our planet is the only one in the solar system

11. What was the “Curtis-Shapley debate” all about

Whether nebulae were in our galaxy or separate galaxies themselves

Whether Cepheid variables were any use for determining stellar distances

Whether our Universe was expanding or not

12. What is a “megaparsec”

A hundred parsecs

A thousand parsecs

A million parsecs

13. What is the typical distance between galaxies?

A few parsecs

A few thousand parsecs

A few megaparsecs

14. The further a galaxy is away..

the faster it moves away from us

the slower it moves away from us

the slower it moves towards us

15. What was the explanation for Hubble’s observations

The Universe is much bigger than we thought

The Universe started from a big bang

The Universe is expanding

16. All the stars you can see with the naked eye are..

in our solar system

in our galaxy

in our cluster of galaxies

17. Which of these is furthest away from us?

Pluto

Alpha Centauri (a star)

Andromeda (a galaxy)

18. A galaxy is 3 x 1021km away. If the Hubble

constant is 2 x 10-18s-1, what is the speed of recession?

1500km/s

6000km/s

0.66km/s

Speed = Hubble constant x distance

19. What is the correct relationship between galaxy distance and

recession speed?

recession speed = Hubble constant x distance

Hubble constant = recession speed x distance

distance = Hubble constant x recession speed

20. Why are Cepheid variables useful?

They allow us to estimate the mass of distant stars

They allow us to estimate the distance to stars and galaxies

They allow us to estimate the temperature of distant stars