Why stars differ in brightness, space telescopes and a human sundial
Answers are for parents and teachers.
1
Write a claim, evidence and reasoning to answer: why does the Sun look so much brighter than other stars?
Claim: it is much closer. Evidence: a torch looks dimmer when farther away. Reasoning: light spreads out, so less reaches our eyes from far away.
2
Make a fact card about the Hubble or the Webb telescope: when launched, where it is, one thing it studies.
Hubble: 1990, orbits Earth, visible and ultraviolet light. Webb: 2021, far beyond the Moon, infrared light.
3
A shadow is 180 cm at 10:00 and 140 cm at 11:00. How much did it shorten in the hour? If it keeps shortening by the same amount, how long is it at 12:00?
180 − 140 = 40 cm shorter; at 12:00 it would be 140 − 40 = 100 cm (in real life it shortens less near noon).
4
Explain why a sundial that is turned round will show the wrong time.
The marks were made for one direction. If the dial is turned, the shadow falls on the wrong marks.
5
Name three safety rules for the human sundial and say why each matters.
Never look at the Sun (eyes can be damaged); wear a hat and drink water (heat); have a grown-up with you (help and safety).