3D Diagram of the orbit of 114 Kassandra
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 (the yellow ball), surrounded by the solar system's innermost planets.
Click and drag the chart to rotate the camera 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 – will come into view.
The date slider lets you move forwards or backwards by a few months to see the motion of the planets along their orbits over time.
The top panel shows where the planets appear in the night sky, as seen 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.
The color coding of the orrery indicates the time of day when each planet is visible. This depends on the direction in which the planet lies, as seen from the Earth. If our line of sight to a planet is widely separated from our sight-line to the Sun, the planet will be easily visible for much of the night. If not, the planet will appear very close to the Sun.
Areas of the chart above which are shaded green are easily visible from the Earth; areas which are red are hidden 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. This color coding can be turned off by deselecting the option "Overlay planet visibility".
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 the points it passes on the first day of each month as it makes its annual circuit around the Sun.