Lessons · Teaching · day, year, seasons and phases
Tilt gives seasons, spin gives day, orbit gives the year
The Earth spins once a day, which makes day and night. It orbits the sun once a year. Its axis is tilted, and that tilt is what makes seasons: the hemisphere tilted towards the sun gets more direct light for longer, and is warmer. Distance from the sun is not the cause.
Hone is a place to practise a career, one idea a day. This is one of its lessons, written out in full and free to read without an account.
In beta. This lesson was written for Hone and has not yet been checked by a state certification officer. Practice material, not professional advice. What that means.
What it is for
'Summer is when we are closer to the sun' is held by most adults, and it is easy to dismantle: it is summer in Australia when it is winter here, and the whole planet is the same distance. The tilt explains that; distance cannot.
How to think about it
Separate the three motions and give each one its consequence, then never mix them. Spin gives day. Orbit gives year. Tilt gives seasons. Moon phases are a fourth thing entirely, caused by how much of the lit half of the moon we can see.
Worked example
Spin on its axis, once a day, gives day and nightNothing to do with the sun moving.
Orbit round the sun, once a year, gives the yearAnd by itself would give no seasons at all.
Tilt of the axis gives seasons: more direct light, for longer, on the tilted hemisphereWhich is why the two hemispheres have opposite seasons at once.
Moon phases come from how much of its lit half faces us, not from the Earth's shadowThe Earth's shadow gives an eclipse, which is a rare event and not a monthly one.
Your turn
Name what causes the seasons.
Seasons are caused by the of the Earth's axis
Solve one, graded on the server
The trap
Explaining moon phases with the Earth's shadow. That is a lunar eclipse, which happens rarely. Phases happen every month and are about which part of the lit half is turned towards us.