George Dishman wrote:

According to this, no:

http://www.iau2006.org/mirror/www.ia...602/index.html

A planet must be "in orbit around the Sun". Even
if the dwarf were part of a binary with another
main sequence star, it would be a planet, just
as "extra-solar planets" are no longer planets!


Hello, there, and while I'm not sure about the first part of
your statement (may we could clarify this binary star
situation you raise), I think that I can clarify the
second point concerning "extra-solar planets."

Actually IAU Resolution 5A restricts its domain to
classifying objects in our own solar system; the question
of defining planets elsewhere is simply left unaddressed,
and likely reserved for a future meeting (the next one in
Rio, 2009).

Thus the resolution doesn't directly affect the status of
any extra-solar planet, much less remove its planethood,
which is simply left officially unaddressed.

It's a bit like the situation in the USA where each of the
50 States might have its own legislation about how towns
or municipalities should be organized. If New York passes
legislation defining a "city" in that State, it doesn't
mean that there are no cities in the State of Massachusetts,
or that what clearly seem cities there are no longer in
that category.

We can debate whether the IAU was wise to adopt a planetary
taxonomy for objects in our own solar system only, as well as
the wisdom of its specific conclusions. However, I would
emphasize that extra-solar planets are just as much planets
as they were on August 23, the day before the resolution was
adopted.

Hmmm, is that really the version that was adopted?

In my post in this thread I include a proposal giving the
text of the adopted version plus some suggested changes so
that people can "correctly" refer to a dwarf planet as "a
planet broadly speaking" in a more relaxed usage. Otherwise
the text is as in the official version, and a vital point
is that they are dividing objects in _our_ solar system into
three main categories, reserving other solar systems for
consideration another time.

Within our solar system, the only domain being considered in
this resolution, the "in orbit around the Sun" might mean
something that isn't a free-floating "planet mass object"
or "planemo" for short as Gibor Basri calls it just drifting
through interstellar space that happens to pass near the Sun;
or a satellite in orbit arounnd some body in our solar system
other than the Sun (e.g. a moon). At least that's how I'd
interpret it.

If it's in orbit around a star other than our Sun, then it's
simply "off the radar screen" for the purpose of this
resolution -- and has the same status (not yet officially
defined) that it did before the resolution.


George



Most respectfully,

Margo Schulter