The Rhythmic Sky Page 10

3. Earth's orbit around the Sun

Both Earth and Moon while orbiting each other, are moving in an orbit around the Sun.
One complete revolution takes about 365 days or one year. But we are not the only one to orbit the Sun of course. There are more planets in our Solar System.

Check the box "trace orbits" and click the play button

Note that the closer the planets are to the Sun, the faster they move. That is a logical consequence of Kepler's laws of orbital motion. For that reason, the outer planets take much longer to orbit the Sun.

Therefore the length of a year is different for each planet.

Earth completes one revolution in 365.25 days.
This means that Earth has a linear speed through the Solar System of about 17,110 kph.

Remember that in all these views we are looking down onto the Earth's North Pole as a convention.

Flashlet Heather Welch


We see that all planets are moving counter-clockwise around the Sun. This relates to the way the Solar System was formed. Read more about that in our EBook "Solar System".