This graph shows all eight planets. Hover, tap, or use the Tab key to read any planet's distance and orbital period, then answer the questions below.
About this graph
What it shows. Each point is one of the eight planets. The bottom axis shows how far the planet is from the Sun in astronomical units (AU); one AU is the average distance from Earth to the Sun, about 150 million kilometers. The left axis shows the orbital period, which is how long the planet takes to travel once around the Sun, measured in Earth years.
Why the curve gets steeper. A planet farther from the Sun has a longer path to travel and also moves more slowly, because the Sun's pull is weaker far away. A longer path at a slower speed means the year grows faster than the distance, so doubling the distance more than doubles the year. This pattern is Kepler's third law of planetary motion.
Why it matters. Knowing how long each planet takes to orbit lets scientists predict where a planet will be far into the future. Mission planners and astrodynamics engineers use this to time spacecraft launches so a probe and a moving planet reach the same place at the same time, sometimes years later.