[meteorite-list] Subject: Re: Habital Planet Discovery Announcement

From: tracy latimer <daistiho_at_meteoritecentral.com>
Date: Sat, 2 Oct 2010 18:30:06 +0000
Message-ID: <SNT120-W6532FA80A617D54FCC2FD4CA6A0_at_phx.gbl>

I have often thought that the Star Trek term "M-class planet", used to designate planets suitable for human-type lifeforms, would not be a bad way to talk about exosolar planets which might support our type of life. It implies other classes with other types of life being possible.
 
Just my 2 dilithium crystals (do they fluoresce, I wonder :)
 
Best!
Tracy Latimer


> Frankly, I have always thought that we have very little
> business deciding what "habitable" means. The very term
> suggests that WE could inhabit the place. The notion that
> WE are the standard by which "life" should be judged is
> highly suspicious to me. It sounds very much like our
> former unjustified assumption that our planet was the
> center of the entire universe.
>
> Is there somewhere a team of alien astronomers going
> over their data on exoplanets with disappointment and
> crossing off the list of targets to pursue further a world
> that's too small, too hot, too wet, and with a significant
> amount of a poisonous gas in its atmosphere. They've
> just eliminated the Earth.
>
> It is very hard for us to conceive of life in any other
> terms than that of the life we know. It's difficult not
> to be a "carbon chauvinist," as Carl Sagan called it.
> It's a very complex system that we know actually
> works. If there is another complex system that works,
> we wouldn't know how it could work, even if we could
> imagine its basics.
>
> As long as we know only one system of living things,
> we lack all basis for judgment. There could be thousands
> of forms of intelligent life in the galaxy, every one with a
> different physical system. Or there could be thousands
> of forms of intelligent life in the galaxy, every one made
> out of carbon, hydrogen, oxygen and nitrogen, and run
> by DNA instructions.
>
> There is no way to calculate the odds of either one.
>
>
> Sterling K. Webb
> ---------------------------------------------------------------------------------
> ----- Original Message -----
> From:
> To: "Sterling K. Webb"
> Cc: ;
> Sent: Friday, October 01, 2010 6:23 AM
> Subject: Re: [meteorite-list] Subject: Re: Habital Planet Discovery
> Announcement
>
>
> > Hi Sterling:
> >
> > I hope that I am not repeating something. Too many emails on too many
> > subjects (not all the metlist) the last few days and getting ready for
> > a
> > conference.
> >
> > One thing seems to be missing in these discussions; how the planets
> > were
> > detected.
> >
> > All of the planets in the Gliese 581 system were detected by
> > spectroscopy.
> > You look at a spectral line from the star and, over time it shifts to
> > the
> > blue and then to the red. This is the Doppler shift as the star moves
> > toward and away from you (respectively) as it is tugged on by it
> > companion
> > planet. It take many orbits of the planet to verify this motion, not
> > just
> > one "signal." The bigger the planet, the more the spectral line
> > shifts,
> > the easier it is to see." The closer the planet is to the star, the
> > shorter the cycle is and the easier it is to see (if the period is a
> > year,
> > it takes several years to see several cycles). This obviously gets
> > very
> > complicated when you have multiple planets and are looking for cycles
> > on
> > cycles.
> >
> > This leads to a very important thing that seems to be left out of all
> > of
> > these discussions.The numbers quoted are MINIMUM masses. The Doppler
> > shift
> > is the shift in the direction of the viewer. These numbers assume that
> > the
> > planet orbits are lined up with the Earth, which would be highly
> > unlikely.
> > For the Gliese planetary system, the inclination of the planets is not
> > known. If their orbits are in reality tilted by say 45 degrees, their
> > masses would be about 1.4 times the numbers quoted. Still not bad. The
> > distance from the star is only dependent on the mass of the star and
> > the
> > distance of the planet from the star (Kepler's Law, orbital period),
> > but
> > the mass is dependent on the inclination of the orbits relative to the
> > Earth.
> >
> > Again, I hope I am not repeating others on this.
> >
> > Larry
> >
> >> Not to doubt the scientific trustworthiness of
> >> the Daily Mail, but they state that the light pulse
> >> was seen December, 2008, "long before it was
> >> announced that the star Gliese 581 has habitable
> >> planets in orbit around it."
> >>
> >> But Gliese 581 c, the first low mass extrasolar
> >> planet found to be near its star's habitable zone,
> >> was discovered in April 2007, and Gliese 581 b,
> >> approximately Neptune-sized and the first planet
> >> detected around Gliese 581, was discovered in
> >> August 2005.
> >>
> >> Discovered at the same time as Gliese 581 c, a third
> >> planet, Gliese 581 d, has a mass of roughly 7 Earths,
> >> or half a Uranus, and an orbit of 66.8 Earth days. It
> >> orbits just within the outer limit of the habitable zone.
> >>
> >> The fourth planet, Gliese 581 e, was announced on
> >> 21 April 2009. This planet, at an estimated minimum
> >> mass of 1.9 Earths, is currently the lowest mass exoplanet
> >> identified around a "normal star." The more distant
> >> Gliese 581 f was found at the same time.
> >>
> >> Gliese 581 was much in the news by December, 2008.
> >> It was known that there were low-mass planets and that
> >> there were planets in the habitable zone. The BEBO
> >> message had been "sent" just two months before, in
> >> October, 2008.
> >>
> >> It is certainly not true that the pulse was "long before it was
> >> announced that the star Gliese 581 has habitable planets
> >> in orbit around it." It was well known.
> >>
> >> Unrepeated signals don't count. Basic rule of SETI.
> >>
> >>
> >> Sterling K. Webb
> >> --------------------------------------------------------------------------
> >> ----- Original Message -----
> >> From:
> >> To:
> >> Sent: Thursday, September 30, 2010 10:40 PM
> >> Subject: [meteorite-list] Subject: Re: Habital Planet Discovery
> >> Announcement
> >>
> >>
> >>> Listees,
> >>>
> >>> And now we have this to contemplate.
> >>>
> >>> http://www.dailymail.co.uk/sciencetech/article-1316538/Gliese-581g-mystery-Scientist-spotted-mysterious-pulse-light-direction-newEarth-planet-year.html
> >>>
> >>> Best to all,
> >>>
> >>> Count Deiro
> >>> IMCA 3536
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Received on Sat 02 Oct 2010 02:30:06 PM PDT