"Extra Solar Planets - what a ripoff!" Topic

I'm sick of these constant announcements, "Hey, we found a planet!"

link

Sure, this is a darn good scientific accomplishment, but, if you recall, the recent brouhaha over Pluto revealed to us that we don't really know what a planet is. In most people's minds, its this thing we're standing on. You could go walk around on Mars, so that's a planet, too. Hopefully we can go live there one day. It would be great to find these things you could live on out there beyond our solar system.

But what do they keep showing us? Gas giants. I understand that this is because the current limits on our methods of detection mean that we could never spot a planet like the one every single human being lives on. For that matter, the entire set of made up aliens includes no notable examples of any beings that could life on these "planets." But when we see a headline that says "Earthlike Planet Found" it always seems to have a hundred times the Earth's mass, meaning that walking around on it is entirely out of the question.

So, by the power of the internet I now pronounce my opinions:

#1 Let's quit arguing about what is and is not a planet. Pluto is Pluto. Unless the Plutonians start gearing up for an invasion, no one cares about it. With a gravity of .06 you can't walk around on it. There are millions of ice balls like it. It has an important place in the history of the discovery of our solar system. Yay for Pluto.

#2 Gas giants are not planets. Sure, they orbit stars, but lots of stars orbit stars and not all gas giants orbit stars. "Gas giants are failed stars' is a problematic statement because it assumes they were trying to be stars, or that all large balls of gravity-coalesced gas should want to be stars. They're big balls of gas. Yay for gas giants.

#3 Moons of gas giants can't be planets, because they're moons. Never mind that two moons in our solar system are larger than Mercury (and a third is smaller by a hair). They can, I suppose, be worlds.

#4 Instead of "Many Early Men Just Sat Up Nights Planning," we will now say "Many Early Men Just Sat Up Nights."

#5 The recent leaps forward in studying the non-star members of other star systems are very important, but please don't try to get us excited by telling us you found a planet. At least, not until you find something we can walk on.

I'm only very mildly annoyed that my opinions contain many contradictions. Let me just swing the bat one more time and be done…

#6 "Planet" is undergoing a tough time in its life right now. It was always on shaky ground, we just didn't realize the trouble it was in. It needs its friends and family to stand by it right now, and not try to stretch its definition even further.

"330 times the Earth-Sun distance from its parent star" my eye. Pluto is only 30 to 50 times the Earth Sun distance.

Andrew

It does seem to be getting to the point where you can't get your PhD in Astronomy without discovering an extra-solar planet.

"this is a darn good scientific accomplishment"

Or is it a demonstration of observational skill? The first one was science. The second one was reprodusing the experience. What are we learning from these now? If you could program an orbiting robot to do it, is it new science anymore?

Of course, astronomy publicises itself through pretty pictures. If someone has developed a new theory of planetary formation that can be tested by finding (or not finding) an extrasolar planet, that would be science.

But could you get the popular press to publich a picture that says "there shouldn't be an extra-solar planet here, and buy gosh there isn't?"

Let's That means Saturn, Jupiter and probable Neptune are not planets. Nope I can't accept that. I'd be more inclined to drop Earth from the list. It wasn't one of the original ones.

Being able to walk on it never entered my definition of a planet

x42

Moons are not "Moons" they are "Natural Satellites." Earth's only natural satellite is call "Moon," "Luna," etc.

You could go walk around on Mars, so that's a planet, too . . . Gas giants are not planets . . . please don't try to get us excited by telling us you found a planet. At least, not until you find something we can walk on.

Andrew, either you're being very tongue-in-cheek or you need an astronomy refresher course.

Personally, I'm exhilarated that astronomers have found evidence of more than 300 extra-solar planets thousands of light-years from Earth. I couldn't care less if I could or could not walk on them. If they orbit a star, and they haven't gone thermonuclear, they're planets.

#4 Instead of "Many Early Men Just Sat Up Nights Planning," we will now say "Many Early Men Just Sat Up Nights."

Darn! I always wanted to walk on Venus.

Okay…

…tongue in cheek, yes,

…Venus – you know, I thought that looked short.

…"If they orbit a star, and they haven't gone thermonuclear, they're planets."

Well, see that includes asteroids, comets, the Oort cloud, a lot of grit and gas, things like whatever Pluto is now, and probably some other stuff.

I feel like we should drop the word "planet" (and ditto for "planetoid") and use a list of things that orbit stars, each of which deserves a new name…

gas giants (probably need a better word since they're only giant relative to the other things that we used to collectively refer to as planets)

rocks

asteroids (rocks with regolith)

frozen gas asteroids

terrestrial planets

comets/Oort cloud objects (the difference being orbit)

It just makes no sense to have a word that includes Earth and Jupiter, but somehow excludes Pluto, Ceres, and Haley's comet. Surely Earth and Ceres have more in common than Earth and Jupiter?

And as for excluding Earth, that makes perfect sense given the origin of the word. The Earth does not "planet" as Pluto and Ceres, non-planets, do.

I guess this stems from years ago, when I learned that a large percentage of stars (most, it was thought at one time) are in double and triple star systems. That makes you take another look at Jupiter-Saturn-Uranus-Neptune. Given a different collective radial velocity at the outset they could have formed one mass, and ignited, and we'd have a two star system with no life anywhere (yes, that's a leap, whatever).

Andrew

We have 9 planets. That includes Pluto, Jupiter, etc. I know this because I learned it in 5th Grade.

Pluto is a planet. Period. End of discussion.

Maybe they just wanted to deserve a new steakhouse burger.

Is Pluto a Planet? by David A. Weintraub is an astronomer's look at the historical and modern understanding of what is (and is not) a planet. Great book, and highly recommended. (And no, you don't have to be a PhD to understand it.)

My brain hurts.

I think finding a gas-giant orbiting a distant star at an insane orbital distance is incredibly cool. Especially since we can resolve it optically.

I also don't complain that current spacecraft are lame because they don't measure up to SF depictions.
-Kle.

Mary's Violet Eyes Make Amorous John Sit Up Nights Pondering. That's how I learned it so that's how the world is ordered. The rest of yez is wrong.

…"If they orbit a star, and they haven't gone thermonuclear, they're planets." Well, see that includes asteroids, comets, the Oort cloud, a lot of grit and gas, things like whatever Pluto is now, and probably some other stuff.

I should have been clearer. I was referring specifically to the extra-solar planets that have been discovered, whether gas giants or otherwise, and your statement that, if you can't walk on them, they're not planets. I certainly agree that the *definition* of "planet" is much more exacting than my statement (as evidenced by Pluto's recent de-planeting). And I, too, recommend Weintraub's book: link

The best definition I read was "big enough to be round and too small to be a star". Yes, that includes Pluto and dozens of other things (Ceres, for one, I think), but so be it

If you want, you can add "and not orbiting another planet", if you don't want to count moons as planets.

Earth's second one is called Cruithne. It was discovered in 1986 and it takes a convoluted horseshoe path around our planet as it is tossed about by the Earth's and the Moon's gravity.

Sorry

Actually, 3753 Cruithne is not a satellite of the Earth; it simply orbits the Sun in a similar orbit, and every so often exchanges gravitational potential energy, as the orbits 'catch up'.

link (footnote 5)

Frankly I'm fascinated by exoplanets. Each new discovery that gets chalked up is a like a mini voyage of discovery. Damn your eyes, Carruthers! Can't you see it? New worlds, by Jove!

We're within 20 years of finding a rocky planet in the Habitable Zone around another star. Life on other planets… something we've been taught to forget about except in Sci-Fi.

I think then humans will truly start getting a handle on their place in their Universe. Nebulae and quasars and black holes don't matter to Joe Average. If there IS life on other planets, complex, evolved life, a lot of societal re-examining may occur.

Maybe it'll cause us to treat our fellow humans and earth animals a bit better… in which case, it'll be well worth it.