Space and gravity, Year 7: more practice

6

HintDivide the angle by the angle turned each hour.

The why90 ÷ 15 = 6 hours. A full turn of 360° takes 24 hours.

The spinning of the Earth

HintWhich body is really moving?

The whyThe Earth rotates once a day, so the Sun seems to cross the sky from east to west.

Your part of the Earth is facing away from the Sun

HintHalf of the planet is always lit.

The whyAs the Earth turns, your place moves into the half that faces away from the Sun, which is in shadow.

Winter

HintThe two hemispheres lean in opposite ways.

The whyWhen the northern hemisphere is tilted towards the Sun, the southern hemisphere is tilted away from it.

The light is spread over a smaller area

HintThink of a torch shone straight down or at a slant.

The whyA higher Sun means the rays hit the ground more steeply and are concentrated on a smaller area, so each square metre receives more energy.

Summer

HintThink about which hemisphere is tilted towards the Sun.

The whyThe northern hemisphere leans towards the Sun in summer, so the Sun spends longer above the horizon. Longest day is about 21 June.

Mercury

HintIt is also the smallest planet.

The whyMercury orbits closest to the Sun.

Jupiter

HintIt is a gas giant.

The whyJupiter is more massive than all the other planets combined.

Venus

HintA thick atmosphere traps heat.

The whyVenus's atmosphere of carbon dioxide traps heat, making it hotter than Mercury, even though Mercury is nearer the Sun.

Neptune

HintThe Solar System's last planet.

The whyNeptune is the eighth and outermost planet.