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Jodrell Bank Discovery Centre
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A-level Physics
Planet Pavilion Questions
1. Use the equation to calculate what the diameter of the model Earth should be.
Real Sun Diameter/Model Sun Diameter ≈ 1.5 x 109 m / 1.5 x 10-1 m = 1010
Model Earth Diameter = Real Earth Diameter / 1010 = 1.2 x 107 m / 1010 = 1.2 mm
2. Write a similar equation to the one given, which can be used to calculate the orrery’s
Earth-Sun distance.
Or:
3. Now use your equation to calculate what the orrery’s Earth-Sun distance should be,
if the orrery were built to scale. 15m
Real Earth-Sun Distance / Model Earth-Sun Distance = 1010
Model Earth-Sun Distance = Real Earth-Sun Distance / 1010 = 1.5 x 1011 m / 1010 = 15 m
4. Find and list an example of the following. Also write a brief description about what it
is and/or what causes it.
a. A nebula
 Orion nebula/Carina nebula
 A huge cloud of gas and dust which collapses to form stars
b. A planetary nebula
 Ring nebula
 A ring of gas and dust left after a Sun-like star dies
c. A supernova remnant
 Cassiopeia A, Crab nebula
 A cloud of gas and dust left after a blue-giant star goes supernova
d. A galaxy
 Andromeda galaxy/NGC 2997/Milky Way (radio image stretching across
entire room)/Large or small Magellanic clouds (dwarf irregular galaxies)
 A gravitationally-bound collection of stars and nebulae, usually containing
around 100 billion stars
e. An active galactic nucleus
 Cygnus A (Sagittarius A* is a black hole, but is not active)
 A galaxy whose central supermassive black hole is active; pulling in material
which heats up, sometimes firing jets of material and/or radio waves and xrays from the poles
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Jodrell Bank Discovery Centre
Answers to students’ worksheets
Space Pavilion Questions
1. What part of the EM spectrum do the telescopes at Jodrell Bank observe? Radio
waves
2. What is the diameter of the Lovell telescope? 76.2 metres
3. The dish of the Lovell telescope is a paraboloid shape. Why is this important? It
focuses the radio waves at the receiver
4. What temperature is the receiver on the Lovell telescope and why does it have to be
this temperature? -260°C, to reduce noise in the electronics (caused by vibrating
free electrons)
5. List two sources of interference for the telescopes. Anything that emits RF noise
such as, Wi-Fi, mobile phones, microwave ovens, etc
6. How long after the Big Bang were the following things formed?
a. Hydrogen and Helium nuclei. 3 minutes
b. Atoms. 380,000 years
c. First stars. 400 million years
7. Explain what happens in terms of a flow of charge when you touch the sphere.
Charge flows from the centre of the plasma ball through the gas, through the
person touching the ball, to the ground.
8. The rotational period of a star is the time it takes to spin around once. The Crab
pulsar spins on its axis 30 times a second. What is its rotational period?
Period = 1 / frequency = 1/30 = 0.033 seconds
9. This shows one way of finding exoplanets. The amount of light from the star is being
measured by a camera (in the red circle) and being displayed on screen. Explain how
exoplanets can be discovered by this method.
Telescopes monitor brightness of stars for long periods. If regular dips in light level
are detected, this could be caused by a planet orbiting that star.
10. Which planet (small or large) is easier to detect? Why? Large. The observed dips in
brightness are larger and more frequent.
11. How do astronomers measure the amount a star is wobbling? From the amount of
Doppler shift measured in its spectra.
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Jodrell Bank Discovery Centre
Answers to students’ worksheets
12. What can astronomers find out about an exoplanet from studying a star’s Doppler
wobble? The mass of the planet and its distance from the star
13. The Lovell telescope is the third largest steerable telescope in the world. The second
and first largest are the Effelsberg telescope and the Robert C. Byrd Green Bank
telescope, respectively. What is the (approximate) diameter of these? 100 m
14. Jodrell Bank is home to the project headquarters for the Square Kilometre Array, a
future radio telescope which will be a giant network of many thousands of detectors.
On what two continents will the SKA detectors be based? Australia and (South)
Africa
15. The European Southern Observatory has built many large telescopes in the Chilean
mountains (South America), such as the VLT and ALMA. What is the advantage of
this location? High altitude means thin atmosphere, which decreases atmospheric
distortion.
16. How does this demonstrate one advantage of building big telescopes? Increases
collecting area, so can see fainter (and further) objects
17. What were bright radio sources originally called, when first discovered in the 1940s?
Radio stars
18. Name the two brightest radio sources that are ‘visible’ from Jodrell Bank. Cygnus A
and Cassiopeia A
19. As a result of the interferometry techniques, the Jodrell Bank astronomers realised
some of these very bright radio sources were coming from extremely small point
sources on the sky. What had they discovered? Quasars
20. What is the equivalent size of the UK’s e-MERLIN network of radio telescopes? eMERLIN has the resolving power of a telescope 217km across.
21. Describe/sketch the view of galaxy M82 with the following sections active.
a. Central core only. Only broad details visible – image is fuzzy
b. Some spiral arms only. Some of the brighter finer details seen, but little to
no large scale structure (depends on how many arms active)
c. Central core and all arms active. (High resolution, large and small scale
structure visible)
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Jodrell Bank Discovery Centre
Answers to students’ worksheets
Planet Path Questions
1. The Earth disc is 70 cm in diameter. Approximate the diameter of the Mars disc.
Around 35 cm (Mars is approximately half the diameter of Earth). 37.2 cm if
calculated exactly from figures given.
2. Venus lies approximately 108 km from the Sun.
a. How far from the model Sun does the Venus disc lay?
108km=1011m. Since 1m=1010m, distance = 1011/1010 = 10m
b. How far is Venus from the Sun in AU?
10m/15m = 2/3, therefore Venus is 2/3 AU away.
3. The total radiation output from the Sun is spread out over an expanding area as it
propagates away from the Sun’s surface. This area is given by the area of a sphere 𝟒𝝅𝒓𝟐 ,
where r is the distance from the Sun. How much more of the Sun’s radiation per square
metre will fall on Venus’ surface than on the Earth’s?
Venus is 2/3 the distance from the Sun, compared to Earth.
Area of the sphere will therefore be smaller by a factor of (2/3)2 = 4/9.
Sun’s radiation per metre squared falling on Venus will therefore be greater
by a factor of 9/4 = 2.25 (approximately 2).
4. Venus’ surface temperature is over 30 times higher than the Earth’s (470°C compared to
15°C). Can this be explained by your calculation in question 3? If not, suggest an
alternative explanation.
This cannot be explained by approximately twice as much radiation falling
per square metre of the surface.
Venus’ atmosphere is thick and high in CO2. This traps infrared radiation; a
massive greenhouse effect causing runaway global warming.
In fact, if we ignore the effect of Venus’ and Earth’s atmospheres and just
calculate their temperature from the Sun’s radiation, Venus is within the
Goldilocks Zone of the Sun and Earth is beyond it.
5. The Mars disc lies 7.5 m from the Earth disc. How far is Mars from the Sun in AU?
(assume the Earth and Mars discs lie on the same radius from the Sun)
7.5m+15m=22.5m. This is 1.5 times the distance from the Sun to Earth.
Therefore Mars lies 1.5 AU from the Sun.
6. The Curiosity rover landed on Mars 6th August 2012. If the planets were in the positions
assumed above, how long would it take a radio signal to travel from the Earth, to the
Curiosity rover on Mars? (speed of light = 3 x 108 ms-1)
The Mars disc lies 7.5m from Earth. 7.5m = 7.5x1010m.
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Jodrell Bank Discovery Centre
Answers to students’ worksheets
Time = distance/speed = 7.5x1010 m/3x108 ms-1 = 250s (4 mins, 10 s)
7. The mass of Jupiter is 318 times that of Earth and Jupiter is 5.2 AU from the Sun.
Approximately how much greater is the force of gravity between the Sun and Jupiter,
compared to the Sun and Earth?
G and M will remain the same. m increases by 318 (≈325), r increases by 5.2 (≈5).
Therefore F increases by factor of 325/55 = 325/25 = 13.
8. The Sun does not have enough mass to become a black hole at the end of its life.
Imagine however, that all the matter in the Sun suddenly collapsed into sphere with a
radius of 3km, thus forming a black hole. What effect would this have on the force of
gravity between the Sun and Jupiter?
None. Although volume has changed, mass (M) and distance (r) has not. Jupiter
(and other planets) will continue to orbit as normal.
9. Saturn is 9.5 AU from the Sun.
a. How far from the model Sun is the Saturn disc?
9.5 x 15 ≈ 10 x 15 = 150m (142.5m if calculated exactly)
b. How long does it take sunlight to travel from the surface of the Sun, to Saturn?
150m = 150 x 1010m
Time = distance/speed = 150 x 1010 m/3 x 108 ms-1 = 50 x 102 s = 5,000 s
(83 mins)
Telescope Path Questions
1.
Sir Bernard Lovell detected these in 1945 using radar equipment. Meteors
2.
Charles Husband was the engineer who built the Lovell telescope.
3.
The Lovell telescope is so powerful it could detect a mobile phone signal on Mars.
4.
What is the diameter of the Lovell telescope’s dish? 76metres
5.
The gear racks on the Lovell telescope are recycled 15-inch gun turrets.
6.
In the 1920s astronomer Edwin Hubble discovered that this is expanding. Universe
7.
The Lovell telescope is painted white to reflect sunlight and stop the metal warping.
8.
The first artificial satellite in space (tracked by the Lovell telescope). Sputnik
9.
Quasars release massive amounts of energy as gas falls into a black hole.
10. What do astronomers call the spinning collapsed core of an exploded giant star?
Pulsar
11. Using radio waves we can peer deep into the heart of our galaxy.
The bold squares spell out the word: OBSERVATORY
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