A research team is deciding where to operate three instruments used for separate observing programmes. Only one instrument can be placed in orbit.
Results from earlier trials are shown. For each radiation type, the ground and orbit instruments had equal effective collecting areas and equal observing times. The signal readings were also corrected for differences in detector sensitivity.
A smaller star image diameter indicates a sharper image.
| Instrument | Ground trial result | Orbit trial result |
|---|---|---|
| Radio telescope | 147 counts | 151 counts |
| Gamma-ray detector | 0 counts | 93 counts |
| Visible-light telescope | star image diameter of 7.2 detector pixels | star image diameter of 2.1 detector pixels |
Explain which instrument should be placed in orbit.
The visible-light telescope will be used on the ground. Explain how the diameter of the star image would change on a night when the air is moving more than during the trial.
75 exam-style questions on Edexcel GCSE Physics 7.3 Stars, covering 7.3.1 Evolution of stars similar to the Sun, 7.3.2 Evolution of massive stars, and 7.3.3 Observing the Universe. Each one has a worked solution and a mark scheme showing where the marks go.