[X] My Assistant

[SFJCody]

http://groups.yahoo.com/group/mpml/message/15111

[Guest_BruceMoomaw_*]

Alan Stern: "The one comment I'll make here is that we have been
careful not to insist that an object BE spherical, only that it be massive enough
to become spherical. This avoids issues like the one you brought up (who
spherical does it have to be?), as well as issues related to rotational
flattening (ala Jupiter and Earth)."

Ah, but whether an object is "massive enough to become spherical" depends on what kind of substance it's made of, and thus how rigid it is. And determining that is a lot more difficult than determining how spherical it actually is.

Moreover, we once again have the problem of fuzzy borders. Pallas (which Mongo accidentally left off his list of Class 3 planets) and Vesta are mildly but significantly non-spherical, and NOT because of rotational flattening. Among the moons, so are Iapetus and Mimas -- to say nothing of Neptune's second-biggest moon Proteus, which looks like nothing so much as a giant marshmallow. And given the number of KBOs, there are bound to be a lot of them that fall into this "Is it spherical or not?" category.

Parenthetically, has anyone come up with a convincing explanation for why Pallas -- alone of all significantly large asteroids -- has that incredible 30-degree orbital tilt? Either something really big ran into it (in which case one would tend to think its parent body would have shattered into multiple objects), or something even bigger brushed past it and tidally yanked it into that orbit.

[abalone]

Alan Stern: "The one comment I'll make here is that we have been
careful not to insist that an object BE spherical, only that it be massive enough
to become spherical. This avoids issues like the one you brought up (who
spherical does it have to be?), as well as issues related to rotational
flattening (ala Jupiter and Earth)."

The chondrules that make up carbonaceous chondrites what about them?

"A roughly spherical aggregate of coarse crystals formed from the rapid cooling and solidification of a melt at about 1400°C. Large numbers of chondrules are found in all chondrites except for the CI group of carbonaceous chondrites. Chondrules are typically 0.5 to 2 mm in diameter and are usually composed of iron, aluminum, or magnesium silicates in the form of the minerals olivine and pyroxene, with smaller amounts of glass and iron-nickel. Together with calcium aluminium inclusions, which predate them by a couple of million years, they are among the oldest objects in the Solar System with an age of about 4.57 billion years. They formed when dusty regions of the solar nebula were heated to very high temperatures, became molten, and then resolidified as tiny droplets. "
From http://www.daviddarling.info/index.html

Were they all once planets and are there enough combinations of letters to name them all if they were?

This shows the pointlessness of trying to invent rules where none are needed.

[Alan Stern]

Chonrules are spherical due to surface tension, not gravity. It's not that
an object *is* spherical, the thing that counts, that reveals it acts like a planet in
a fundamental way, is that it is massive enough to have its shape controlled
by self-gravity.