QUESTION:
How do you know that Pluto's and Neptune's orbit overlap?  Have you
obtained this information through telescope viewing or have you just
guessed?

ANSWER from Peter Stockman on April 25, 1996:
We haven't actually seen Pluto in front of Neptune, as in a solar eclipse
or the passing of one of Jupter's moons across the face of Jupiter.  But
we have measured the positions of Pluto, Neptune, and the other planets
as they appear from month to month and year to year. From those measurements,
it is possible to calculate the actual orbits of the planets around the
Sun. That was done hundreds of years ago for the brighter planets but
we can only due the calculations for Pluto using relatively modern data.

The agreement between observations and calculated orbits for the planets
and their satellites was one of the foundations of modern astronomy and
physics.So astronomers are pretty confident about such things -- even
though we haven't
seen Pluto go through a complete orbit of the Sun yet!DONE


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