Studying space; final review

The Sun is a star: it gives off light and heat itself. Eight planets orbit the Sun: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. Planets do not give off light; they reflect sunlight. Moons orbit them: the Earth’s natural satellite is the Moon. Earth is the only planet known to have life: it has water, air and a suitable temperature. Stars are very far away and look like tiny points at night. Space is observed with telescopes; space telescopes work outside the Earth’s atmosphere. Robot spacecraft are sent to far planets. Never look at the Sun directly, with a telescope or binoculars — it damages the eyes; a special protective filter is needed.