PDA

View Full Version : Could Gliese be the so called planet x/nibiru?



Wakatah
2007-Dec-26, 05:58 AM
I have been looking up somethings and came up with gliese recently
discovered extrasolar planet.

http://en.wikipedia.org/wiki/Gliese_581

I don't know its orbit but its not going to hit earth, but it may be able to debunk
the myth.

Anyone else know any more info about the gliese star systems and red, brown, dwarfs and etc?

I hear one of them may be habitable.

Celestial Mechanic
2007-Dec-26, 03:38 PM
I have been looking up somethings and came up with Gliese recently discovered extrasolar planet.

http://en.wikipedia.org/wiki/Gliese_581

I don't know its orbit but it's not going to hit earth, but it may be able to debunk the myth. [Snip!]
The very first sentence from the Wiki article is most pertinent:

Gliese 581 is an M2.5V red dwarf star located 20.4 light years away from Earth.{Emphasis mine}
It is almost five times farther away than the Alpha Centauri system. It won't hit the Earth in any of our lifetimes. ;)

Of course this won't stop Planet X believers like Nancy L. for whom celestial mechanics has no meaning and planets can just roam about the inner Solar System at will.

As for Nibiru, its believers claim a highly elliptical orbit for it with a period of 3600 years, again something that it couldn't have if it were orbiting some other star.

Eckelston
2007-Dec-26, 07:48 PM
Welcome to the board Wakatah.

Note that Gliese is the name of a catalogue of nearby stars. If you want to refer to an individual star you would use Gliese 581 or Gl581 so we won't confuse it with any other star in the catalogue.

With that out of the way, I'll just add something to what CM said. 20 light years is a lot. It is over 1 million astronomical units (the distance from the Sun to the Earth), or about 1.8 trillion (million million) kms (1.1 trillion miles).

At a speed of 30km/s it would take 60 billion seconds or about 2000 years to get here. Of course it wouldn't just start rushing in our direction for no good reason, this is just illustrate the distances involved.

Generally the distance between stars is huge compared to the distance between planets in a single star system.

Also planets also tend to orbit their own star. The only way they can break orbit is by interacting with another planet in the system. If another planet passes very close by it can transfer some of its kinetic energy allowing the first planet to escape the gravity of the star. These events happen very rarely (on the order of hundreds of millions or billions of years).

grant hutchison
2007-Dec-26, 08:11 PM
In the particular case of Gliese 581, its movement towards us is relatively slow, and its transverse motion is relatively fast. So it will never get much closer than it is at present.
From the figures in the Gliese catalogue, closest approach is 20.01 light years in ~40,500 years time.

In general, very few stars will come within a light year of Earth in the foreseeable future, so extrasolar planetary systems are entirely separate from our own system.

Grant Hutchison

Noclevername
2007-Dec-26, 09:53 PM
I hear one of them may be habitable.

"May be" is a long distance from "is". We know there is a planet that might be within the right distance from Gl581 and the right mass to have liquid water, if it has water, and if it has an atmosphere which can hold enough (but not too much) heat, and if its composition is similar enough to Earth. If all those reqirements are met, and if it has the right chemistry on the surface, then there is an entirely unknown chance that it might have the right conditions for life as we know it. If so, there is another entirely unknown chance that it might have developed life. Lot of ifs, some of them entirely unpredictable.

Eckelston
2007-Dec-27, 12:51 AM
"May be" is a long distance from "is".

"May be" can be a long distance from "is".

Noclevername
2007-Dec-27, 02:16 AM
"May be" can be a long distance from "is".

Nope. May be is a wide field, "is" is a known singleton. The set of "may bes" is a three-dimensional infinity, while "is" is a single point.

Eckelston
2007-Dec-27, 02:59 AM
Nope. May be is a wide field, "is" is a known singleton. The set of "may bes" is a three-dimensional infinity, while "is" is a single point.

That kind of 'is' doesn't exist in science. There is always uncertainty, but sometimes it's so small that we can ignore it.

Noclevername
2007-Dec-27, 03:13 AM
That kind of 'is' doesn't exist in science. There is always uncertainty, but sometimes it's so small that we can ignore it.

Well, then the term doesn't belong in science.

EDIT: Actually, the term wasn't used in science, it was used in a post.

I hear one of them may be habitable.


Having the implication that that means something more than just a range of possiblities.

Eckelston
2007-Dec-27, 11:44 PM
Well, then the term doesn't belong in science.

EDIT: Actually, the term wasn't used in science, it was used in a post.


Certainty doesn't exist anywhere outside of math and logic. There's a continuum between complete uncertainty and 'almost certain'. 'Is' doesn't mean certainty it means very high confidence. This is how it's used in science and this is how it is used in everyday speech.

The only reason why I'm pointing out the blindingly obvious is that you have used this artificial distinction between things we know and we don't as a rhetorical device.


Having the implication that that means something more than just a range of possiblities.

I'm not a native speaker and I may be missing some context but that's not how it sounded to me.

Noclevername
2007-Dec-28, 12:58 AM
The only reason why I'm pointing out the blindingly obvious is that you have used this artificial distinction between things we know and we don't as a rhetorical device.


No, I haven't. I've pointed out that what I thought the OP was implying was not accurate.

And it's no "artificial" distinction, otherwise why have science at all? Its purpose is to increase our knowledge and get us as close to certainly as possible (not entirely certain, just constantly closer-- like lightspeed, it can't be reached but you can keep accelerating).

Eckelston
2007-Dec-28, 02:38 AM
No, I haven't. I've pointed out that what I thought the OP was implying was not accurate. {/quote]

I wasn't reacting to what you thought, I was reacting to what you wrote.

BTW I was also referring to an earlier conversation where you more or less had said that there are facts and there are things we basically don't know anything about (paraphrasing). Since you repeated this in this thread, I couldn't help saying that I disagreed.

[quote]And it's no "artificial" distinction, otherwise why have science at all?

It's artificial to say that we either 'know' or 'don't know' something. Yes, the purpose is to increase our certainty, but not to stuff all statements in either of these categories.

Jim
2007-Dec-28, 04:50 AM
Guys, you're wandering way off topic and threatening to hijack the thread.

If you want to pursue this further, either go to PMs or start a new thread. You could call it, "It depends on what your definition of "is" is." No, wait, that's been used.