Mysterious Planet May Be Cruising For a Bruising 104
sciencehabit writes "Something is orbiting the bright star Fomalhaut in the constellation known as the Southern Fish, but no one knows exactly what it is. New observations carried out last year with the Hubble Space Telescope confirm that the mysterious object, known as Fomalhaut b, is traveling on a highly elongated path, but they haven't convincingly nailed down its true nature. But if it is a planet, as one team of astronomers thinks, we may be in for some celestial fireworks in 2032, when Fomalhaut b starts to plough through a broad belt of debris that surrounds the star and icy comets within the belt smash into the planet's atmosphere."
Meanwhile, astronomers recently announced the discovery of the most Earth-like exoplanet yet seen, which orbits a G-type star, has a radius 1.5 times that of Earth and a year of about 242 days.
Re:25 Ly away (Score:5, Interesting)
Minkowski spacetime does not work that way. There is no "already" in relativity.
Correct. I find that most people have a very hard time grasping that time is a local phenomenon, and that there is no universal clock that ticks for both us and distant space. We observe time everywhere as linear, so we think it is both linear and universal.
Words like "since" and "then" can only apply to our local time, and no time has passed "since" the light left the distant star - that "since" is only valid in our time frame, not outside our cone of causality.
Words like "light year" and "light minute" add to the confusion, because in our Newtonian frame of mind we then think that "the" time actually ticks when light goes from A to B, but there is no "the" time.
As Einstein said, "I came to realize that time itself is suspect".
Re:It's not a planet (Score:5, Interesting)
*devil's advocate (lame attempt)
Ok, so basically what you are saying is:
"One of these things is not like the others, but rather than actually give due dilligence to a truly thoughtful definition of what a planet is (and thus, what it isn't) that would apply amid the growing dataset of observed orbiting non-stellar objects, we will just pull something out of our asses because we don't want to let pluto into our arbitrarilly segregated "so definately a planet" club, because we don't want to admit such a dinky object, because if we did, then all that rabble would have to be entered too!"
Here's a better definition for planet.
A substellar mass that has achieved a stable, non-random orbit with a stellar mass, and engages in stable harmonic relationships with other orbiting substellar masses.
That would include pluto, due to its harmonic relationship with neptune, and its orderly orbit, even if that orbit is highly eccentric. It also enables objects like extrasolar hot jupiters to be planets, where arbitrary requirements for the shape of the orderly orbit would cause exclusion; many hot jupiters race in toward their parent stars and get roasted regularly due to highly eccentric orbits. Eccentricity is therefor not a quality to cause exclusion, since eccentric orbits are far more prevelent than nearly circular ones. This drives home the point about stable harmonic relationships with other orbiting masses. Crossing eccentric orbits can be harmonically stable.
So, basically, the GP's post about the definition being made specifically to exclude pluto for nebulous and arbitrary reasons is absolutely true, given that eccentrically orbiting extrasolar masses that cross each other's orbits at intervals are abundantly prevelent in the observed galaxy?