Shadowy Man

Unfortunately, the story at the link provided by Tom Sawyer doesn't give much information.

Remember, the mass of the planet discovered, assuming that it is done in the typical manner, is a lower limit. What is actually derived is M*sin(i), where i is the inclination of the planet's orbit.

So, this planet they discovered around a sun-like star is at least twice the mass of Jupiter and orbiting at almost half the Sun-Jupiter distance. I would imagine that if the planet is too massive, it may be difficult to have an earth-like planet close in because of gravitational perturbations.

Rhaedas

Earth technically moves our sun, but so minorly I'm not even sure we could see it here in our system. Just not enough mass.

Correct, plus we flew by Neptune with Voyager 2, and got nice pictures.

Arken

Don't most physicists now believe that the universe is not, in fact, endless? Wouldn't an infinitely large universe violate some basic precepts?

Shadowy Man

Actually, Pluto's discovery was more accidental. The calculations that predicted a planet beyond the orbit of Neptune proved later to be in error. It was just plain luck that Tombaugh found Pluto where he did.

Shadowy Man

According to Marcy & Butler's Review on the Detection of Extrasolar Giant Planets , the stellar radial velocity induced by an orbiting companion is



putting in the values for the Earth and the Sun, you get about 5 cm/s (times sin(i)).

Current technology allows us to get to about 3 m/s, maybe 1 m/s under the best conditions. So, we still need almost two orders of magnitude improvement on the current technique (or change techniques) before we can detect an Earth around a Sol.

Rhaedas

Thanks Shadowy Man for the numbers...

Plus, the inclination of the orbit has to be pointed somewhat at us. We detect the wobble by doppler changes in the star's light; if we're looking at the star system from the poles, there aren't any changes, nor would a large planet block light.

Shadowy Man

Yep, that's why there's a sin(i) in there.

Rhaedas

I figured...just wanted to clarify the rareness of detection.

Or actually, due to that rareness of angle, the fact we find a lot of stuff orbiting other stars, albeit only the big ones we can see so far, it speaks to how common solar systems probably are. So given the number of stars, there has to be a lot of similiar conditions that are hospitable to self-replicating forms.

Arken

Saying that there 'has to be' is a bit premature considering that we don't even know for certain what is needed for life to begin yet. I think it's safer to say 'it is very likely'

Rhaedas

You're correct of course...my opinion crept in there.

Would my earlier statement on finding something else in our system raise that probability to 1 though? It seems to me that the chances of having two freak abiogenesis events in one place, but nowhere else in the universe, is virtually zero.