How many planets in our solar system? - part 2
- Thread starter mike wightman
- Start date
M
Malenfant
Guest
Blimey, that was quick with the moon announcement, I only heard about this yesterday!
Interesting stuff. And yes, there could be more out there.
Interesting stuff. And yes, there could be more out there.
M
Malenfant
Guest
Um. Hot on the heels of 2003 EL61, astronomers have found another one - and this could be a whopper bigger than Pluto!
http://news.bbc.co.uk/1/hi/sci/tech/4730061.stm
http://www.gps.caltech.edu/~mbrown/planetlila/
Might still be preliminary, but... erk!!!
http://news.bbc.co.uk/1/hi/sci/tech/4730061.stm
http://www.gps.caltech.edu/~mbrown/planetlila/
Might still be preliminary, but... erk!!!
M
Malenfant
Guest
Nope.
The IAU hasn't actually determined a definition for what a planet is anyway - til that is agreed on then we won't really know how many planets we have. I'd agre that we have eight major bodies orbiting the sun, but how many planets we have depends on what definition they end up using.
For now Pluto is the ninth planet though - the IAU have already stated that they are not going to drop that, for historical reasons and frankly I think they'd be right to keep its planet status for those reasons too. Now that a larger object has been found though, it remains to be seen whether that will be referred to as a "10th planet".
Technically Pluto is merely a large (and now not the largest) member of the Kuiper Belt, but I think that can be acknowledged while still referring to it as a planet. I think it's OK to make a single exception to the rule for historical reasons surely, as long as that is made clear.
The IAU hasn't actually determined a definition for what a planet is anyway - til that is agreed on then we won't really know how many planets we have. I'd agre that we have eight major bodies orbiting the sun, but how many planets we have depends on what definition they end up using.
For now Pluto is the ninth planet though - the IAU have already stated that they are not going to drop that, for historical reasons and frankly I think they'd be right to keep its planet status for those reasons too. Now that a larger object has been found though, it remains to be seen whether that will be referred to as a "10th planet".
Technically Pluto is merely a large (and now not the largest) member of the Kuiper Belt, but I think that can be acknowledged while still referring to it as a planet. I think it's OK to make a single exception to the rule for historical reasons surely, as long as that is made clear.
mike wightman
SOC-14 10K
How are you going to include them in your system design rules Mal?
Roll 2d, DM subtract no. of gas giants in the system, for number of planets in the system's Kuiper Belt, perhaps?
Roll 2d, DM subtract no. of gas giants in the system, for number of planets in the system's Kuiper Belt, perhaps?
M
Malenfant
Guest
Oh I dunno, just roll 2d and be done with it probably.Originally posted by Sigg Oddra:
How are you going to include them in your system design rules Mal?
Roll 2d, DM subtract no. of gas giants in the system, for number of planets in the system's Kuiper Belt, perhaps?
mike wightman
SOC-14 10K
Mal, are there any "educated guesses" for how many more of these things may be out there?
Could there be something larger still waiting to be discovered?
Could there be something larger still waiting to be discovered?
M
Malenfant
Guest
I think one of the articles mentions the possibility of Mars- or even Earth-sized KBOs out there.
I don't know about guesses as to exactly how many bigger objects are out there, but I suspect 'more' would be a good ballpark
.
I don't know about guesses as to exactly how many bigger objects are out there, but I suspect 'more' would be a good ballpark
Despite the IAU, I really think we should think of our Solar System as having eight planetary bodies.
Not precicely on-topic, but I remember several years ago an hypothesis that Sol was a double star but that its companion had 'burnt out' exhausted its nuclear fuel. I presume that theory has now died the death.
Not precicely on-topic, but I remember several years ago an hypothesis that Sol was a double star but that its companion had 'burnt out' exhausted its nuclear fuel. I presume that theory has now died the death.
Fritz_Brown
Super Moderator
Cardinal, the theory might have died, but the concept is intriguing....
Mal! Besides wiggly orbits, what would this concept do to our Solar system? Would it be a ways out there (beyond Pluto/Neptune)? How close would it have to be to muck up life on Earth? Could it have a dead civilization on a planet in its hab zone?
Mal! Besides wiggly orbits, what would this concept do to our Solar system? Would it be a ways out there (beyond Pluto/Neptune)? How close would it have to be to muck up life on Earth? Could it have a dead civilization on a planet in its hab zone?
I believe he's talking about Nemesis, a theoretical star with a 26 million year orbit. It was theorized by observing a series of species extinction events which seemed to take place every 26 million years (with some gaps). Supposedly, the last major extinction event was 13 million years ago, meaning Nemesis - if it exists - is at its aphelion.
Assuming Nemesis gets no closer than Pluto's average distance (30 AU?), and is at aphelion, what would be its expected distance from the sun now? (I don't know how to calculate that, so yes, it's a question.) If that distance is more than about a lightyear, then it's well within possibility that such an object had its orbit altered by some other neighboring star and therefore the theory should be considered disproven (until observation proves it right).
Assuming Nemesis gets no closer than Pluto's average distance (30 AU?), and is at aphelion, what would be its expected distance from the sun now? (I don't know how to calculate that, so yes, it's a question.) If that distance is more than about a lightyear, then it's well within possibility that such an object had its orbit altered by some other neighboring star and therefore the theory should be considered disproven (until observation proves it right).
M
Malenfant
Guest
http://www.space.com/scienceastronomy/solarsystem/nemesis_010320-1.html
Provides some info on Nemesis. It's not impossible, but so far we haven't found any such companion.
Provides some info on Nemesis. It's not impossible, but so far we haven't found any such companion.
Keklas Rekobah
SOC-14 1K
The Sol system has four planets and a lot of insignificant dust-specks; none of which are named "Nemesis."
-KR-
-KR-
M
Malenfant
Guest
Erm, where'd you get only 'four planets' from?
far-trader
SOC-14 10K
I'm guessing the Heretic KR is only counting rocky bodies of significant size, not gas giants and iffy planetismals
It's like new math
It's like new math
Keklas Rekobah
SOC-14 1K
Four planets: Jupiter, Saturn, Uranus, and Neptune. Everthing else is a dustball by comparison.
I seem to remember this as a quote from a Traveller-based story... or was it a GURPS sidebar?
Doesn't matter.
I seem to remember this as a quote from a Traveller-based story... or was it a GURPS sidebar?
Doesn't matter.
