1Can scientific theories change with time?
2Can the distance between the Earth and the Moon, and between the Sun and the Earth, be expressed in the metre and the kilometre that we use in daily life?
3What is the Big Bang theory? What evidence supports it?
4Define the astronomical unit and the light year, and write their values in metres.
5Why is the light year used instead of the kilometre to measure the distances of stars?
6Show by calculation that one light year equals \( 9.46 \times 10^{15} \, \text{m} \).
7Why was Pluto removed from the list of planets?
8What is meant by the Big Crunch?
9'No body in the universe is at rest.' Justify this statement with examples.
10What does the discovery of the planet TOI 700 d show? Give short information about it.