No, and nothing is. The distances go from 58 million km to 4,515 million km, so a picture to scale has the inner four planets in one dot; the sizes go from Mercury to a Sun a hundred and nine times wider than Earth, so a picture to scale has no Mercury. The order is right, the ratio of the years is right, and the real numbers are in the panel.

Why does Neptune hardly move?

Because its year is 165 of ours. At the fast setting an Earth year takes two seconds, so Neptune takes five and a half minutes to go round once. That is the correct answer and it is worth letting a class sit with: nobody alive has seen Neptune complete an orbit since it was found.

Why are the names in a list rather than on the planets?

Because a label stuck to a planet going round the Sun goes round with it and spends half its time upside down. The list also gives a much bigger target than a moving circle, which matters at a board.

Are the numbers of moons right?

They were when this was written, and the outer planets keep gaining them: Saturn went from 82 to 146 in a single year of new discoveries. Mercury and Venus have none and Earth has one, and those three are not going to change.

Solar System

Science · Year 5–Year 6

The planets going round the Sun, at the real ratio of their years.

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About the solar system

The planets go round the Sun at the real ratio of their years. One press sets how long an Earth year takes on screen and everything else follows from its own year, so Mercury goes round four times while Earth goes round once, and Neptune barely moves. That ratio is the Year 5 objective and it is the one thing a picture in a book cannot show.

Line them all up and press play, and a class watches Mercury lap the rest. Scattered is what the sky actually looks like: the planets are never in a line.

The Moon goes round the Earth, twelve times to the Earth's one, which is the other half of the objective.

Tap a planet in the list and the board gives its distance from the Sun, how long its year is, how wide it is and how many moons it has. The list is also a much easier target than a moving circle on a whiteboard.

The picture is not to scale, and no picture of the solar system is. To scale for distance, the inner four planets are one dot beside the Sun and Neptune is off the end of the board. To scale for size, the Sun is a hundred and nine times wider than Earth and Mercury is invisible. What is true here is the order, the ratio of the years, and every number in the panel.

How to use it on your whiteboard

1Speed sets how long an Earth year takes: twenty seconds, eight, two, or Stop.
2Lined up starts them all from the same line, which is the quickest way to see which one gets round first.
3Tap a planet in the list, or tap the planet itself when they are stopped, to read about it.
4Moon hides the Moon going round the Earth.
5Tap Fullscreen to fill the board.

Questions

Is it to scale?: No, and nothing is. The distances go from 58 million km to 4,515 million km, so a picture to scale has the inner four planets in one dot; the sizes go from Mercury to a Sun a hundred and nine times wider than Earth, so a picture to scale has no Mercury. The order is right, the ratio of the years is right, and the real numbers are in the panel.
Why does Neptune hardly move?: Because its year is 165 of ours. At the fast setting an Earth year takes two seconds, so Neptune takes five and a half minutes to go round once. That is the correct answer and it is worth letting a class sit with: nobody alive has seen Neptune complete an orbit since it was found.
Why are the names in a list rather than on the planets?: Because a label stuck to a planet going round the Sun goes round with it and spends half its time upside down. The list also gives a much bigger target than a moving circle, which matters at a board.
Are the numbers of moons right?: They were when this was written, and the outer planets keep gaining them: Saturn went from 82 to 146 in a single year of new discoveries. Mercury and Venus have none and Earth has one, and those three are not going to change.