[X] My Assistant

[JRehling]

Probably some perfect "grand tour" type alignment, where each spacecraft-planet encounter is as close-in to the planet as possible for a departure trajectory that's approximately tangent to the planet's orbit or as close to tangent as possible.

Eris is also well off of the ecliptic at present (and for a long time coming). I doubt that keeping things in the ecliptic for three flybys then counting on Neptune to provide all of the work to acquire a high inclination is feasible. Maybe a Jupiter-Saturn combo could do it, assuming the rings weren't a problem.

That would actually be a scenario that would unfold fairly often.

Uranus is actually in a pretty good position right now for an assist to Eris, but it'll soon move out of that good position and not come back for 8 decades. Neptune, however, is moving into position, but again, Neptune can't bend the path down in very good proportion to Jupiter's bending it out.

In only 230 years or so, Eris will come within 40 AU of the Sun. Let's plan on an Eris Orbiter/Lander then. Start the buzz now.

[Alan Stern]

You probably already know about The Great Planet Debate meeting coming this week near DC, if not, see:
gpd.jhuapl.edu.

To register for Great Planet Debate conference web participation, click: http://tinyurl.com/6xcqec
Watch the talks and debate on line!

-Alan

[dvandorn]

Do also remember that whatever definition of planet upon which we achieve consensus doesn't only need to account for solar system objects. Such a definition ought also to include bodies orbiting other stars.

I can conceive of a lot of solar systems in which major planets have not (yet) cleared their orbital neighborhoods. Young systems, for example, where accretion is *nearly* finished, or older systems where large planets are migrating closer to, or farther away from, their stars. Or systems in which a hot mega-Jupiter, orbiting its star in two or three days, finally spirals in and hits the Roche limit.

Are all of the bodies in such systems not planets because of these circumstances? Does "planet" only and forever describe only eight bodies in orbit around our Sun, disregarding bodies that are already described as "extrasolar planets"?

Or do we need to get better data on other systems to find out just how many adjustments we need to make to *any* definition of planet based only on our experience of our own solar system?

-the other Doug