[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

[stevesliva]

Three (or more) issues here:

1. The IAU definition sucks.
2. The IAU lacked authority.
3. 'Planet' could end up being as imprecise a term as 'continent' or as precise a term as 'metal.'

You go in an infinite loop from #3 back to #1 because of the whole "cleared its neighborhood" crapola. So a planet is the biggest thing around? Right, like lakes are bigger than the biggest ponds around. Mountains are bigger than the biggest hills around.

A lot of people are either bothered or not bothered by number 3. With some terminology that predated science, like the word 'metal,' we have been blessed with some rather precise terms. This is generally because they had specific, quantized characteristics, and not relative characteristics. Metals were defined as ductile, shiny, malleable, whatever. They were not defined as less shiny than diamonds and more shiny than rocks. Turns out there is conductivity, electrons, etc, but what is a metal and what is not has been relatively constant.

On the other hand, 'Continent' has somehow not seen obsolescence due to science discovering plate tectonics, even though we now know there is a fault above India and not one between Europe and Asia. So Europe isn't really a continent, and India is??? Try to read wikipedia for a precise definition of 'continent.' It's all about "convention." Try telling every grade school teacher that we now have the continents of Eurasia and India. In my opinion, either way would be fine, but you are just redefining an admittedly imprecise term. The maps of the world on wikipedia's plate tectonics article and wikipedia's continent article do not match. Science doesn't match the pre-existing term, yet it will still adopt it when discussing "supercontinents" and the like. Schools still teach students the continents, even though it's not a precise term.

You can count me as not bothered by #3-- I'd take it either way-- precise, or defined "by convention." But I certainly understand the disgust with the IAU's botched attempt at "precise."