Expert: Steven LJ Russo - 2/10/2008

Question
QUESTION: Do all planets travel in their orbits around the Sun at the same speed?

I work with 3rd graders and we are going to model the Solar System with the kids being the planets so we can see that the longer the orbit, the longer time needed to complete one year.  I thought it would be helpful to know the planets' comparative speeds to share that with the kids when we do the activity.

Thank you.



ANSWER: If you go to this link:

http://www.windows.ucar.edu/tour/link=/the_universe/uts/orbits_data.html

you will ind a data table of planetary orbits.

Steve




---------- FOLLOW-UP ----------

QUESTION: Great chart.  I see that as the planets' locations are farther from the Sun, their revolution speed is slower.

So would it be correct to say that the reason some planets have longer "years" is due to a longer orbit as well as a slower speed?

Answer
Sue:

Of course, if a planet is farther from the Sun, it's orbital path will be longer in distance.

It is the Sun's gravity that pulls the planets around, so the Sun's gravity will pull stronger on Mercury (so a fast orbital speed), and weaker on Pluto (so a slower orbital speed).

Steve