Stoopid Science

Phillip Blanchard · **Posted:** Mon Mar 15, 2004 6:27 am

NASA is expected to announce today that a likely planet has been discovered orbiting the sun about 6 billion miles from Earth.If confirmed as our solar system's 10th planet, the super-distant object - tentatively dubbed Sedna by scientists after the Inuit goddess of the sea - would bump Pluto from the back of the pack as the smallest and most distant known planet from the sun.Sedna is made up of ice and rock and has a diameter of about 1,200 miles. It's so far away it would take a space shuttle 40 years to reach it. (New York Post)***It's not really a "planet." And the space shuttle could try for 400 years to reach it and fail.***

Matthew Grieco · **Posted:** Mon Mar 15, 2004 12:25 pm

Isn't there honest dispute as to what constitutes a planet? The jury was still out on Pluto, last I heard.

Phillip Blanchard · **Posted:** Mon Mar 15, 2004 3:43 pm

<blockquote>quote:<hr>Originally posted by Matthew Grieco:
Isn't there honest dispute as to what constitutes a planet? The jury was still out on Pluto, last I heard.<hr></blockquote>Precisely.

Matthew Grieco · **Posted:** Mon Mar 15, 2004 5:02 pm

<blockquote>quote:<hr>Originally posted by blanp:
Precisely.<hr></blockquote>Then why your conclusory statement that it's not a planet?

Phillip Blanchard · **Posted:** Mon Mar 15, 2004 7:05 pm

NASA is calling it a "planetoid."

paulwiggins · **Posted:** Mon Mar 15, 2004 9:49 pm

Does all this mean we are going to have to revise all those honestly written and ethical horoscopes that some of us run?[ March 15, 2004: Message edited by: Paul Wiggins ]

Jackie · **Posted:** Mon Mar 15, 2004 11:34 pm

Big-ass ball of ice takes up too much hed space, I guess.

Rio · **Posted:** Tue Mar 16, 2004 12:16 am

<blockquote>quote:<hr>Originally posted by Matthew Grieco, directed at blanp:
Then why your conclusory statement that it's not a planet?<hr></blockquote>Some historical perspective is required on this.For the first 48 years we knew of Pluto's existence, we thought it was a genuine planet, larger than Mercury. But then in 1978, astronomers discovered that Pluto had a large moon, relative to Pluto anyway. Seems that Pluto itself wasn't really that large after all. Oops! So what were they going to do, rewrite all the astronomy books to say the solar system has only eight planets after all? Actually, some astronomers still think they should.Fortunately, with this latest discovery, scientists have an out. They don't have to declare that Sedna's the 10th planet, given that 1) Pluto is still the smallest acknowledged planet, and 2) Sedna is smaller than Pluto. So they can say, "Sedna's not a planet, it's not large enough to qualify!"Granted, Pluto's not much bigger. And if astronomers later find bigger versions of Sedna out there, scientists may have to rewrite all those grade-school astronomy books, one way or another, after all.[ March 16, 2004: Message edited by: Gary Kirchherr ]

ADKbrown · **Posted:** Tue Mar 16, 2004 12:38 pm

I heard a discussion of this point on NPR this morning. There are three opinions:1. Pluto is a planet, Sedna is a planet and so are many other hunks of ice and rock orbiting the sun that remain undiscovered.2. Only objects large enough so that their own gravity gives them a spherical shape are planets. Plato would qualify. I think they said Sedna would, too.3. Pluto is too dinky to be a planet, and so is Sedna.One suggested criterion is whether the object in question is a lot bigger than the other objects in its neighborhood. But I can't remember where this fits in in the above list.(Yesterday, NPR referred to Sedna as a planet, but BBC called it a planetoid.)

DominEditrix · **Posted:** Tue Mar 16, 2004 3:06 pm

<blockquote>quote:<hr>Originally posted by Paul Wiggins:
Does all this mean we are going to have to revise all those honestly written and ethical horoscopes that some of us run?<hr></blockquote>The astrologers are already at it: Update

Matthew Grieco · **Posted:** Tue Mar 16, 2004 4:00 pm

It figures that my sex life would be governed by a frigid goddess six billion miles away.

Rio · **Posted:** Wed Mar 17, 2004 12:50 am

<blockquote>quote:<hr>Originally posted by ADKbrown, on defining what a "planet" is:
One suggested criterion is whether the object in question is a lot bigger than the other objects in its neighborhood. But I can't remember where this fits in in the above list.<hr></blockquote>If Sedna is pretty much all by its lonesome out there in orbit, presumably the largest thing for millions of miles, that's an argument in favor of calling it a planet. But if a bunch of other Sedna-like things are out there, as some believe, then that argument goes out the window. It's the same reason that even the largest asteroids aren't considered "planets."This "biggest thing around" argument is more useful for explaining why large moons like Ganymede and Titan aren't considered planets, even though they're both bigger than two planets (Mercury and Pluto). Otherwise, some wise guy would be arguing that Jupiter and Ganymede are actually part of a "binary planet system."[ March 17, 2004: Message edited by: Gary Kirchherr ]

Matthew Grieco · **Posted:** Wed Mar 17, 2004 4:48 pm

This story is directly on point.

ADKbrown · **Posted:** Thu Mar 18, 2004 12:38 pm

One thing I don't understand: I keep reading that Sedna is a ball of rock and ice. It was a big deal when we found evidence that water existed on Mars. So why isn't it a big deal if ice (and hence water, unless they mean another kind of ice) exists on Sedna? And how do we know it contains ice?

Rio · **Posted:** Thu Mar 18, 2004 1:27 pm

<blockquote>quote:<hr>Originally posted by ADKbrown:
It was a big deal when we found evidence that water existed on Mars. So why isn't it a big deal if ice (and hence water, unless they mean another kind of ice) exists on Sedna? And how do we know it contains ice?<hr></blockquote>Water ice on Mars would be a big deal because it would make a manned mission there far more feasible. Not just because of the water itself, but because it could provide a source of oxygen. Scientists were looking for evidence of underwater polar ice on the moon for the same reason. Ice on Sedna, on the other hand, will be a who-cares issue until Zefram Cochrane gets around to inventing warp drive.As for how one can tell whether a planet contains water, I believe astronomers can get an idea of a heavenly body's chemical composition with the help of radio telescopes, which indicate which atoms and molecules it has.

ADKbrown · **Posted:** Thu Mar 18, 2004 3:21 pm

I didn't follow the story closely, but I thought people were excited because if water is/was present, then Mars might have supported life at one time.

Rio · **Posted:** Fri Mar 19, 2004 12:08 am

There was that, too. Fair to say, the reason why the discovery caused so much excitement depended a lot on whom you talked to.

nstockdale · **Posted:** Fri Mar 19, 2004 1:39 am

Glad some of you are on top of this. Thanks for keeping the rest of us on point!

adering · **Posted:** Fri Mar 19, 2004 10:05 am

<blockquote>quote:<hr>Originally posted by Gary Kirchherr:
Seems that Pluto itself wasn't really that large after all. Oops! So what were they going to do, rewrite all the astronomy books to say the solar system has only eight planets after all? Actually, some astronomers still think they should.<hr></blockquote>Well, isn't that the whole point of science? That you do rewrite the text books? And from another post about why some of Jupiter's moons aren't called planets. Wouldn't that be because they orbit a planet in addition to the sun?

Rio · **Posted:** Fri Mar 19, 2004 12:04 pm

<blockquote>quote:<hr>Originally posted by Fussbudget Alex:
Well, isn't that the whole point of science? That you do rewrite the text books?<hr></blockquote>
Sure. But read the article that Matthew links to in his previous post. There's a lot of resistance to reclassifying Pluto, not just from scientists but from the population at large. Until now, this wasn't a fight that the "eight planets" advocates could hope to win.When Pluto was thought to be the only planetlike thing in its part of the solar system, traditionalists had a stronger argument for maintaining the nine-planet status quo. If on the other hand Pluto and Charon, its moon, are among many Sedna-like objects beyond Neptune, the case for stripping Pluto of its "planet" status becomes stronger. But scientists are going to have to find more planetoids before that can happen. <blockquote>quote:<hr>And from another post about why some of Jupiter's moons aren't called planets. Wouldn't that be because they orbit a planet in addition to the sun?<hr></blockquote>That's too simple a criterion, given that two heavenly bodies in each other's respective gravity technically orbit each other.That argument appears to be easy to dismiss because in most cases a planet is so much larger than its moons, but what about Pluto and Charon, which are relatively close to the same size?The point is, if you're going to say a planet is anything that's a given size, or spherical, then you're going to need "the largest thing around" rule too, or else acknowledge that Ganymede's part of a binary planet system. You can't leave the definition of "planet" and "moon" nebulous (no pun intended); that's what got us into so much trouble with Pluto's status in the first place.

Phillip Blanchard · **Posted:** Tue Mar 23, 2004 2:36 am

From 1999: "We've already found objects 1/3rd the diameter of Pluto," says David Jewitt [of the University of Hawaii], "even though we have examined only a tiny fraction of the sky. An example is 1996 TO66, which is 800 km diameter. It would be incredible in its own right if Pluto proved to be the only 2000 km object. I think we'll have Pluto II, Pluto III....within a few years." (Science at NASA)

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