View Full Version : Found! Two planets in a class of their own

Johannes de León
Wednesday, September 1st, 2004, 07:07 PM

A new class of planets has been found orbiting stars outside our solar system, in a possible giant leap forward in the search for Earth-like planets that might harbour life, scientists said.

"We can't quite see the Earth-like planets yet, but we are seeing their big brothers, and hopefully we will be bearing down on these small-mass planets soon," said Dr Paul Butler of the Carnegie Institution of Washington (http://www.ciw.edu/), the co-discoverer of one of the new planets.

The two new planets are about 15 to 20 times more massive than Earth and are about the mass of Neptune.

They have diameters about two or three times the size of our home planet, astronomers said.


The newly discovered Neptune-sized extrasolar planet circling the star Gliese 436 (Image: NASA)

That makes these new bodies different from most of the other so-called exoplanets found in the past decade outside our solar system.

These other planets, more than 100 of them, are generally about the mass of Jupiter, about 318 times Earth's mass, and are thought to be balls of gas, completely inhospitable to life as we know it.

But the newly discovered planets indicate that planetary systems around other stars could have the same assortment of planets as in our solar system: big gassy ones like Jupiter, middle-weight rocky ones like Neptune and just possibly, relatively small rocks like Earth.

If scientists find an Earth-mass planet, they could then search for one just the right distance from its star, making it temperate enough to allow for the presence of water on its surface, considered a requirement for life.

No-one has ever seen an extrasolar planet. Most have been detected by looking for a characteristic wobble in a distant star, a sign that a planet's gravity is tugging on the star in a specific way.

Zipping around the stars

Butler and fellow planet-hunter Professor Geoffrey Marcy of the University of California (http://www.berkeley.edu/), Berkeley, discovered one of the Neptune-mass planets around a small star called Gliese 436, some 30 light-years away in the constellation Leo, a stone's throw in cosmic terms.

The other neptunian planet was discovered by Barbara McArthur of the University of Texas (http://www.utexas.edu/), Austin. This one is orbiting the star 55 Cancri in the constellation Cancer, about 40 light-years away. A light-year is about 10 trillion kilometres, the distance light travels in a year.

Both zip around their respective stars in three days or less, at a small fraction of the distance that Earth orbits the sun.


This artist's concept shows the newfound Neptune-sized planet, one of the smallest extrasolar planets detected to date, circling the star 55 Cancri (Image: NASA)

The planet around 55 Cancri is the fourth planet detected there, but the others in that system fit the gas-giant mold, the scientists said.

The two new discoveries are the smallest planets found so far around sun-like stars, the U.S. astronomers said.

They acknowledged that a European team of astronomers announced last week the discovery of a planet some 14 times Earth's mass, a so-called super Earth.

But Dr Alan Boss of the Carnegie Institution said credit for such discoveries is based on when academic papers are submitted for publication, not on when they are announced to the media.

Under this rule, Boss said, the European team would get credit for discovering the third Neptune-mass planet.

But the U.S. team would get credit for the first and second as its research has been accepted for publication in the Astrophysical Journal (http://www.journals.uchicago.edu/ApJ/).

"It's a stiff competition but we're quite friendly," Marcy said of the European planet-hunting team. "... We recognise that the best science is done when there's a bit of tension, a bit of competition, but friendly, with science as the ultimate goal."

Comet man dies

In other astronomy news, the U.S. researcher who originated the idea that comets were comprised of ice and mineral dust, Professor Fred Whipple, has died at the age of 97.

Whipple's 'icy conglomerates' theory explained why some comets arrived at destinations earlier or later than predicted and refuted a notion widely held in the early 1950s that comets were comprised of sand held together by gravity.

Ultimately, close-up pictures of Halley's comet proved Whipple's 'dirty snowball' theory correct.

He also influenced space flight by inventing the Whipple Shield, a thin outer skin of metal on spacecrafts to prevent damage from meteors. The mechanism explodes a meteor on contact and improved versions are still in use.

Whipple had been director of the Harvard-Smithsonian Center for Astrophysics (http://cfa-www.harvard.edu/) for almost two decades.

[ Source (http://www.abc.net.au/science/news/stories/s1189762.htm) ]

Mistress Klaus
Wednesday, September 1st, 2004, 08:28 PM
Earth is such a speck in the universe. I dare anyone to say that we are the only living entities with any so-called 'intelligence'. Our planet barely makes the status of a Tonka toy in relation to the grand vortex of the universe. :) :) ....

Hail the unknown and what can Never be fully understood by mankind. :)

Wednesday, September 1st, 2004, 08:53 PM
That's really fascinating, maybe there is a first sign of a second galaxy like our own, with a second earth. After all, the Indians knew 2300 years before (Rig-Veda) that such Spheres exist (each with their own Gods and Planets), and that impresses me much.
And, like Skadi Ju87 said, I doubt that we are the only (more-or-less) intelligent beings out there.