Discovering a New Planet!

Suppose you are part of the scientific investigation team which has just discovered a new planet orbiting a sun-like star named 51 Pegasi, 42 light years from Earth. A periodic shift in the spectrum emitted by the star indicates that the newly discovered planet has an orbital period of 4.2 days. Other information indicates the planet has a mass which must be at least half that of Jupiter.

Your task is to estimate the mean orbital radius of the planet about thestar. A press release about this discovery will beforthcoming shortly, and you need to be sure that you have all the facts right!

#1 Record your estimate for the mean orbital radius of the planet about 51 Pegasi.

Orbital Radius = m

#2 How does this distance compare to the Sun-Earth distance? How about the Sun-Mercury distance?

Would you like more information about this actual October 1995 discovery? Check it out!
Click here to return to the Lesson Map