The Astronomy Thread

[Arioch]

And New Horizons will be at Pluto in July... it's going to be cool.

[Sweforce]

And New Horizons will be at Pluto in July... it's going to be cool.

Pluto have bunch of moons of it's own and they still pulled it's status as a planet. five of them. A mighty dwarf that. http://en.wikipedia.org/wiki/Moons_of_Pluto so yes this will be cool.

[Zakharra]

http://www.telegraph.co.uk/news/science ... verse.html

If true, that's an interesting find. And empty space in the universe that is relatively close to our galaxy.

[GeoModder]

Pluto have bunch of moons of it's own and they still pulled it's status as a planet. five of them. A mighty dwarf that. http://en.wikipedia.org/wiki/Moons_of_Pluto so yes this will be cool.

Why not call the Moon a planet then? Some mighty 'moon' we have there floating in the neighbourhood. I mean, its even more massive then all known dwarf planets combined, and the Sun has more of a gravitational grip on it then Earth...

[icekatze]

hi hi

That, or you could call the Earth a dwarf planet, since it hasn't cleared its orbit of like objects.

[GeoModder]

I guess that's where the barycenter comes into play.

[icekatze]

hi hi

Big news in the world of astronomy: New Horizons passed its closest approach to Pluto today!

[Arioch]

Unfortunately, it will take more than a year to download all of the data from the probe, to say nothing of analyzing it.

It is neat to finally have a picture of what Pluto looks like, though.

[GeoModder]

I wonder if next 'Pluto year' the dwarf planet would look different from space. I assume some of those surface 'features' we see now are a result of atmospheric condensing (or the start of that proces since Pluto is still in local 'Summer').

[icekatze]

hi hi

Since Charon has a lot more visible surface features and cratering, I think the general hypothesis is that Pluto probably has some sort of process that is refreshing its surface.

[Arioch]

I wonder if next 'Pluto year' the dwarf planet would look different from space. I assume some of those surface 'features' we see now are a result of atmospheric condensing (or the start of that proces since Pluto is still in local 'Summer').

It was also my thought that the dark equatorial areas could be condensation of some kind of organic compounds... but Pluto's axial tilt is so extreme that right now it should be the north pole that is warmer, not the equator.

Pluto has a lot of surface ice (it's very bright), while Charon seems darker and more rocky at first glance. All of Pluto's 5 moons are in the same weird plane, which suggests they are the remnants of a massive collision.

[GeoModder]

Now I can only hope that during my lifetime there'll be at least a flyby mission to Eris to see if an object a quarter more massive is indeed smaller then Pluto.

[Arioch]

I did find it amusing that they made a big deal about Pluto now being the largest KBO... when the diameter was revised from 2302 km to 2370. As if the estimate for Eris (~2300 km, last I heard) is now suddenly more accurate.

I get the feeling that the New Horizons team suffers a bit from Pluto Inferiority Complex. I notice during the briefings they seem to conspicuously avoid the use of the term "dwarf planet."

[Mr Bojangles]

I watched "Direct From Pluto" on the Science Channel and if it was in anyway accurate, then the New Horizons team is firmly in the camp of "Pluto's still a planet!" I mean, they showed clips of the NH PI at a local school that held a mock protest to have Pluto be called a planet again. Basically, the impression that I got was that they were pretty unhappy with the IAU.

[GeoModder]

Its bound to happen. After all, Pluto is their baby so to speak.
Whether we call it a planet, KBO, dwarf planet, or whatever, I'm happy there's this resurgence of wonder about the mysteries of those objects we still haven't seen from up close.
Its been a good couple years now, with Vesta, Ceres, and now the Pluto/Charon binary revealed as interesting worlds in their own right.
If I could make a list for the next objects to visit, Eris, Chiron, and the moons of Uranus and Neptune would be on it.

[Arioch]

The IAU planet definition is pretty nonsensical; the bit about having to clear its orbit of similar objects is absurd, as I don't see how that has anything to do with the qualities of being a planet. It seems quite common that multiple proto-planets can form in the same orbit (Earth supposedly had a planet called Theia in the same orbit), and though they usually eventually collide, it's possible that with the right orbital resonances with surrounding planets, such a dual-planet orbit could be stable. And, as far as I'm aware, such planets could potentially be extremely massive. How can such an object, potentially more massive than Earth, be classified as a "dwarf planet?" The classification also puts Ceres and Pluto in the same category, when Ceres is a rocky asteroid, and Pluto is an icy Kuiper Belt Object that's more than 100 times more massive.

It's also a distinction without any real scientific value. It's purely for academic bookkeeping; planetarium curators would rather subtract one "planet" from the list than have to constantly be adding new ones.

[Mr Bojangles]

I certainly wasn't surprised to know how the NH team feels towards Pluto's status. Nor am I surprised by how people in general feel about it. Personally, whether we ultimately classify it as a dwarf planet or a regular planet, I don't much care. What I care most about is the apparent lack of scientific rigor applied to the existing definition by the IAU; the decision was rushed and certainly lacked real consensus.

So long as the definition is strong and unambiguous, I'm fine with eight planets or potentially scores of them.

[Razor One]

On the one hand, defining a planet in rigid terms is like trying to define "How long is a piece of string", and Pluto is generally small enough, distant enough, and eccentric enough for them to nudge it off and avoid irritants like adding dozens of new planets because other KBO's are larger and such.

On the other hand, the New Horizons team have been working on this for ten years and long before Pluto was left out in the cold, so it's completely understandable that they're in the Pluto is a Planet camp.

Personally, I'm of the opinion that Pluto should have been grandfathered in. The Voyager and Pioneer plaques both bear a model of our solar system with the nine planets there. Generations of children grew up learning that Pluto was a planet. Yes, there is no scientifically sound reason to do so, but the definition the IAU uses is equally unscientific, since Earth orbit crossing asteroids would deem Earth not to be a planet, since that essentially means Earth has yet to clear its orbit.

Grandfathering Pluto in as a planet and designating all subsequent objects found as KBO's would have been the better solution. It would've been the exception that proved the general rule, would have avoided the awkwardness of redesignation, and would've kept the cantankerous eccentric planet that is Pluto in the family instead of locking it in the attic and hoping it starves.

[Namaphry]

I dunno. If we grandfather it in, then we have to keep explaining it to children hundreds of years down the line, including those born on other worlds and around other stars, and we Terrans would end up looking like sentimental nitwits in the process.

We can set everything beyond Neptune's orbit into its own group... and so long as we're anthropomorphizing Pluto, I've gotta say that giving it the same status as Neptune is pretty demeaning to the big blue thing. Even Neptune's moon Triton is bigger than Pluto.

I prefer the 'Kuiper Belt Object' definition, just like I'd call Ceres an asteroid. The whole 'dwarf planet' thing just seems like it's a half-baked conciliatory gesture. Classifying Pluto as a 'plutoid', though, is pretty funny. I'd let them get away with that as an official definition, if I were hypothetically in a position to intervene.

[icekatze]

hi hi

Speaking of grandfathering things in, we're still going to have to explain to children hundreds of years down the line why the solar system has a completely different classification system for planets than any other system in the universe.