What is the shape of planetary orbits?

Answer Early astronomers believed the shapes of all planetary orbits were circular. In truth, the orbits of solar planets--planets that orbit our sun--are mostly elliptical, bordering on circular, while t... Read More »

Top Q&A For: What is the shape of planetary orbits

What shape are planetary orbits?

The orbits of the planets are ellipses around the sun. According to, an ellipse is "a curved line forming a closed loop, where the sum of the distances from two points (foci) to eve... Read More »

Who surmised the planetary orbits to be elliptical?

In 1609 Johannes Kepler published "Astronomia Nova", in which his first two laws of planetary motion are given. These laws state that the orbits of planets are elliptical and that the area swept by... Read More »

Who discovered that planetary orbits are ellipses?

The fact that the planets orbit the sun in elliptical rather than circular orbits was initially discovered by Johannes Kepler, using astronomical data collected by Tycho Brahe. He formulated three ... Read More »

What orbits Mars?

Two moons -- Phobos and Deimos -- orbit Mars. These moons are significantly smaller than the Earth's moon. Phobos is less than 17 miles wide, and Deimos is less than 10 miles wide. Both have low or... Read More »