Which planet revolves the fastest around the Sun?

All planets revolve around the Sun (yes, Pluto too, but it’s not a planet). But which is the fastest to make a turn in its orbit?

Among the many useful little functions that arrived with iOS 16 on the iPhone, the lock screen did not go unnoticed. You can make the solar system appear there, with the position of its stars in real time. Obviously, the movement of the planets that appear on the screen is not noticeable, even if you stare at the image for a few moments.

In our system, each planet does evolve at its own pace around the Sun. But, what is the fastest of all in this movement of revolution around the star? It’s little Mercury : it completes an orbit around the Sun the fastest. It also happens to be the closest planet to the star.

Planets revolving around the Sun (objects not to scale).

Here are the speeds of revolution of the different planets in the solar system (in kilometers per second and in kilometers per hour), and the period of revolution (that is, the length of the year on each, in days or Earth years). Pluto is added to the list, although it is not a planet, but a dwarf planet.

Planet Speed ​​in kilometers per second Speed ​​in kilometers per hour period of revolution
Mercury Speed ​​in kilometers per second47.87km/s Speed ​​in kilometers per hour172,332 km/h period of revolution87.97 days
Venus Speed ​​in kilometers per second35.02km/s Speed ​​in kilometers per hour126,072 km/h period of revolution224.7 days
Earth Speed ​​in kilometers per second29.78km/s Speed ​​in kilometers per hour107,208 km/h period of revolution365.256365 days
March Speed ​​in kilometers per second24.077km/s Speed ​​in kilometers per hour86,677 km/h period of revolution686.93 days
Jupiter Speed ​​in kilometers per second13.07km/s Speed ​​in kilometers per hour47,052 km/h period of revolution11.86 years old
Saturn Speed ​​in kilometers per second9.69km/s Speed ​​in kilometers per hour34,884 km/h period of revolution29.42 years old
Uranus Speed ​​in kilometers per second6.81km/s Speed ​​in kilometers per hour24,516 km/h period of revolution83.75 years old
Neptune Speed ​​in kilometers per second5.43km/s Speed ​​in kilometers per hour19,548 km/h period of revolution163.72 years
Pluto Speed ​​in kilometers per second4.74km/s Speed ​​in kilometers per hour17,064 km/h period of revolution247.92 years

The closer a planet is to the Sun, the faster it is

The fact that the planets are less and less fast, the farther they are from the Sun, is no coincidence. The closer an object is to the star of the solar system, the faster it must go to maintain its orbit. This speed of movement is also not constant. At perihelion, the stars advance more quickly in their orbit: at aphelion, they advance more slowly. However, the variations are quite negligible, since the planets of the solar system have almost circular orbits around the Sun.

For comets, on the other hand, the situation is different, because their orbit around the Sun is very eccentric. We see this with the example of Halley’s comet. In 1948, when the comet was at aphelion (well beyond the orbit of Neptune), it was moving at a speed of 0.91 km/s. In 1986, at perihelion (in the orbit of Venus), the comet had a speed of 54.55 km/s.

All about the star of the solar system, the Sun

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