Carl Sagan Would Do Cartwheels...

Lost Cause

It's a wrap!
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Oct 7, 2001
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.....at this latest news! Do you think SETI should focus more on these systems given they are older in origin than our system? Is anybody out there? Or are you a cosmic isolationist?

WASHINGTON (AP) - For the first time, astronomers have found a distant planetary system with at least one planet whose orbit resembles a member of our solar system.

Geoffrey Marcy of the University of California, Berkeley, and Paul Butler of the Carnegie Institution of Washington said Thursday they have found a planet about five times the size of Jupiter circling a sun-like star at an orbital distance very like that of the solar system's biggest planet.

The newly discovered planet is one of three planets circling a star, called 55 Cancri, that is about 51 light years away from Earth.

"This is the first time that we've found a family of planets that has some similarities to our own solar system," Marcy said Thursday at a news conference.

The new planet circles 55 Cancri at a distance of 5.5 Astronomical units, close to the 5.2 AU orbit of Jupiter. An AU is the distance between the Earth and the sun, about 93 million miles.

The two other planets around 55 Cancri are also Jupiter- or Saturn-sized bodies, but they orbit much closer to the parent star. One is in an orbit of about 9 million miles and the other is about 23 million miles.

Marcy and Butler also announced they had found 13 other planets orbiting distant stars, bringing to 91 the total number of known extrasolar planets.

Just a decade ago, the concept of other stars having planets was "in the realm of science fiction," noted Anne Kinney, director of NASA 's astronomy division.

The Marcy-Butler team has found most of the 91 extrasolar planets. The group uses a technique that measures the very slight wobble of a central star and then uses the magnitude of this motion to determine the presence of orbiting planets, the size and shape of their orbits and their mass. The technique works only for larger planets and cannot detect those much smaller than about half the mass of Saturn.

Marcy and Butler said they had a hint years ago that 55 Cancri had a large planet in a Jupiter-like orbit, but to confirm the conclusion required measurements for at least one complete orbit of the planet. The new planet takes about 13 years to circle its star, close to the 11.86 years it takes Jupiter to orbit the sun.

"All other extrasolar planets discovered up to now orbit closer to the parent star and most of them have had elongated, eccentric orbits," said Marcy. "This new planet orbits as far from its star as our own Jupiter orbits the sun."

The planet-hunting team is in the midst of a long-term project to search each sun-like star in the Milky Way up to a distance of 150 light years. A light year is the distance light travels in a year in a vacuum, about 5.8 trillion miles. The Milky Way is the home galaxy of the solar system and contains about 200 billion stars.

The astronomers are using large telescopes at observatories in both the northern and southern hemisphere to probe the entire sky visible from Earth.

Although the 55 Cancri planet is the first to resemble a solar system-like orbit, Butler said he expects the astronomers will find many such planets over the next decade.

The Marcy-Butler team has been trying to detect extrasolar planets for more than a decade. A planet must make one whole orbit of its star before astronomers can be certain of its characteristics. Planet candidates first detected five to 10 years ago are now being confirmed on an almost daily basis, and it is not unusual to confirm two or three new planets a week, he said.

Over the next decade, he said, the team should be able "to give hard numbers" on how many solar systems like our own are in the Milky Way.

Marcy said astronomer Greg Laughlin of the University of California, Santa Cruz, calculated it is possible for an Earth-sized planet to exist in a stable orbit between the two inner planets of 55 Cancri and the giant planet orbiting at 5.5 AU.

The calculations suggest small rocky planets like the Earth or Mars could be present in orbit of 55 Cancri, said Marcy, but that theory cannot yet be tested.

Among the other new planets found by the Marcy-Butler team is what may be the smallest extra-solar system planet yet discovered. Orbiting a star called HD49674, the team found a planet that is just 15 percent the size of Jupiter — only about 40 times larger than the Earth.

___

On the Net:

Planet search: http://exoplanets.org

:D
 
We have no idea how many systems there are out there that have planets, let alone whether any of those planets have any sort of life (let alone intelligent life). I think it's most likely that somewhere out there there is other intelligent life; however, the universe is a huge place.
I don't think we should focus our efforts to look for alien life on just a few systems simply because we know those systems contain planets. Look at how many systems we've found that contain planets in just the past few years - the discoveries will probably continue at this rate, if not speed up. There's a whole universe to explore. And what if said alien life isn't on a planet, but on some kind of spaceship? Or what if they're something Star Trek-y that doesn't need a planet to survive? (Carl Sagan advocated that life didn't necessarily have to be carbon-based, or be on an Earth-like planet, as many other scientists believe. I tend to agree with him.)
However, given all the possible means of communication, and given the way that radio waves disperse through space, I really doubt SETI will find anything in the near future. Yes, it is possible, and yes, it would be an earthshatteringly profound discovery - the discovery that we are not alone in the universe would change our way of life forever - but I doubt it will happen.

But, despite all that, three cheers for SETI :)
 
Here's another article on the same story, from USA Today:

Star systems similar to ours found

By Dan Vergano, USA TODAY

European and U.S. astronomers Thursday
announced the discovery of two solar systems
with planets in orbits similar to our own, a
finding that boosts the odds that they harbor
extraterrestrial life.

In all, astronomers announced they had found
27 previously unknown planets, bringing the
number of known planets orbiting nearby stars
to more than 100.

One group led by Geoffrey Marcy of the
University of California-Berkeley and Paul
Butler of the Carnegie Institution of
Washington, D.C., released details of 15 planets. A European team led by
Swiss astronomer Michel Mayor of the University of Geneva unveiled details of
12 more, several days ahead of a planned announcement at a science meeting.

"There must be billions of planetary systems like our own within our Milky Way
galaxy," Marcy says. His team found that the star 55 Cancri hosts a Jupiter-like
planet occupying a near-circular orbit, much like Jupiter's. The planet, a giant
ball of gas, takes about 14 years to circle 55 Cancri, a star 41 light-years away
in the constellation Cancer. (A light year equals 5.89 trillion miles.)

Marcy's team calculates that a planet like Earth could safely orbit 55 Cancri
without disturbance from planets orbiting the star.

The European team also reports on a different solar system with a planet that
resembles Jupiter in size and its circular orbit.

Astrobiologists say solar systems whose outlying gas giants follow near-circular
orbits might be more likely to have planets with life. In theory, the Jupiter-like
objects would screen smaller, Earth-like planets closer in to their star from
comet impacts, as Jupiter apparently has done over the history of our own solar
system. Plus, a planet with a circular orbit has less chance of disturbing the
orbital stability of other planets.

Says astrophysicist David Spergel of Princeton University, "Now we have the
first report that suddenly our solar system is not that special."
 
I don't have anything upon which to pontificate, really. Just the statement that it would be incredibly egocentric to think that there's absolutely no life out there. Astounding...there must be something out there.

And no, I've never been abducted by aliens.

But don't ask about anal probes...

:p
 
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