3D Diagram of the orbit of 101 Helena
An orrery is a model of the solar system that shows the positions of the planets along their orbits around the Sun.
The chart above shows the Sun at the centre, surrounded by the solar system's innermost planets.
Click and drag the chart to rotate the viewing angle, or use your mouse wheel to zoom in and out. Alternatively, you can use the slider below the chart to adjust the zoom level. As you zoom out, the solar system's outer planets – Jupiter, Saturn, Uranus and Neptune – come into view.
The date slider allows you to move forwards or backwards by a few months to see the motion of the planets along their orbits.
The top panel shows where the planets appear in the night sky from the Earth. The yellow line marks the zodiac – the annual path of the Sun across the sky – and the grey lines show constellation boundaries.
Planet visibility shading
When enabled, the color coding indicates the time of day when each planet is visible from Earth. If our line of sight to the planet is widely separated from the Sun, the planet will be easily visible for much of the night. But if not, the planet is likely to be lost in the Sun's glare.
Areas of the chart above which are shaded green are visible for much of the night. Areas which are red are obscured by the Sun's glare. Areas which are dark blue are visible in the morning sky, while areas which are light blue are visible in the evening sky.
Labelling of the orbits
By selecting the option "Mark perihelion / aphelion", labels can be added which mark the closest and further points from the Sun along the orbits of each of the planets. The Earth's orbit is additionally labelled with its position at midnight UTC on the first day of each month.