Shop Windows to the Universe

Check out the fun Earth science related bumper stickers in our online store! Express yourself!

What is Orbital Velocity?

Click for full size

How fast a planet travels as it orbits around the Sun is called orbital velocity.

Planets that are close to the Sun have large orbital velocities because of Keplerís second law of planetary motion. This means that Mercury, the closest planet to the Sun, is the fastest moving planet in our solar system moving at about 48 km/sec! Earth is orbiting slightly more slowly at a speed of about 30 km/sec and poor Pluto, far from the Sun, travels less than 5 km/sec.


Our Solar System
Click on image for full size (15K GIF)
Windows Original

Learn more about orbital velocity and experiment with Keplerís second law!

Shop Windows to the Universe Science Store!

Our online store includes issues of NESTA's quarterly journal, The Earth Scientist, full of classroom activities on different topics in Earth and space science, as well as books on science education!

Windows to the Universe Community

News

Opportunities

You might also be interested in:

Cool It! Game

Check out our online store - minerals, fossils, books, activities, jewelry, and household items!...more

Kepler's 2nd Law: The Speeds of Planets

Kepler's second law he again discovered by trial and error. Kepler realized that the line connecting the planet and the Sun sweeps out equal area in equal time. Look at the diagram to the left. What Kepler...more

Pluto

Pluto is a frigid ball of ice and rock that orbits far from the Sun on the frozen fringes of our Solar System. Considered a planet, though a rather odd one, from its discovery in 1930 until 2006, it was...more

AU

AU stands for Astronomical Units. It is a useful way to measure the distances in interplanetary space. It is the distance between the Earth and the Sun, which is about 93 million miles. For reference,...more

The Spiral of the IMF

The solar wind is formed as the Sun's top layer blows off into space, carrying magnetic fields still attached to the Sun. Gusts form in the solar wind associated with violent events on the Sun. Particles...more

Spiral Path of Material

For a planet to be affected by a blob of material being ejected by the sun, the planet must be in the path of the blob, as shown in this picture. The Earth and its magnetosphere are shown in the bottom...more

The SAR Arc

The aurora we are most familiar with is the polar aurora. This is what people are talking about when they say the northern or southern lights. But there are other less-known aurora, such as SAR arcs....more

The Effect of Aurora on the Atmosphere

This figure shows the effect of the aurora on the atmosphere. When FAC's enter the atmosphere and create the aurora, they heat the atmosphere suddenly and abruptly. This creates an impulse which travels...more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part by the National Science Foundation and NASA, our Founding Partners (the American Geophysical Union and American Geosciences Institute) as well as through Institutional, Contributing, and Affiliate Partners, individual memberships and generous donors. Thank you for your support! NASA AGU AGI NSF