1. Select mode by clicking on 'Earth' or 'Sun' in the top right:
Earth mode (default) - shows a close-up of the Earth.
Sun mode - shows the Earth orbiting the Sun.
2. Earth mode:
Change the view by clicking on the view buttons. Custom view allows you to rotate the whole simulation (including where the light-source is) by clicking and holding on the left and right buttons.
Pause/Resume rotation allows you to control the Earth's motion.
Click and drag anywhere on the left panel to manually rotate the Earth.
Time of year - Drag the slider to change the axial tilt, simulating different times of year.
Day night lighting - toggling this on and off changes between universal lighting and 'realistic lighting' which illuminates the Earth with a Sun off to the right of the screen.
Show Sunbeam places a beam of light directed at the Earth (and places the view into custom mode), adjusting the Left/Right buttons will bring the beam into clearer view. Adjusting the 'Sunbeam latitude' slider will raise or lower the beam, with both the shape of its circle, and its shading showing how the Sun's light is less intense as you move to the poles.
Clicking the Day-night length toggle enables you to do a short experiment to explore the length of a day at different points, and at different times of year (toggling this on will temporarily disable a range of other functionality).
Click anywhere on the Earth's surface to make a red dot appear.
Clicking start will cause the Earth to complete one full rotation below, and the timers below will track how long the spot spends in the darkness and in the light.
Press reset to enable another measurement to be taken, and to re-enable any temporarily disabled functionality.
Sun mode:
Click Pause/Resume orbit to control the orbital motion, it is set to complete one orbit every 60 seconds.
Click Pause/Resume rotation to control the rotation of the Earth.
Drag the Time of Year slider to move the Earth to specific points in its orbit.
Toggle the Display UK button to place a marker over the UK.
EarthSun
View
Rotation
X-rotation
-90°0°90°
Time of year
Dec 21Mar 20Jun 21Sep 22Dec 21
Display
Sunbeam latitude (vertical; position)
SouthNorth
Day-night length
Click on the Earth's surface to set a location, then click start to track how many hours in a day that spot spends in the daylight, and how long in the night. Click pause to pause this process, and reset to reset it and enable you to change the time of year or location.