Science Fiction
Dictionary
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
 |
Habitable Planet Gliese 581g Is A 'Ribbon World'
Gliese 581g lies right in its star's habitable zone, where it liquid water can exist. It is one of six planets orbiting Gliese 581, a red dwarf just 20 light-years from Earth.
The new planet is about three times the mass of Earth, which indicates it is probably rocky and has enough surface gravity to sustain a stable atmosphere. It orbits its star once every 36.6 Earth days at a distance of just 13 million miles.
That means the planet has a blazing-hot daytime side, a frigid nighttime side, and a band of eternal sunrise or sunset where water — and perhaps life — could subsist comfortably. Any life on this exotic world would be confined to this perpetual twilight zone, Steven Vogt says, but there’s room for a lot of diversity. [Astronomer Steven Vogt of the University of California, Santa Cruz, who designed some of the instruments that helped find the planet.]
“You can get any temperature you want on this planet, you just have to move around on its surface,” Vogt said. “There’s a great range of eco-longitudes that will create a lot of different niches for different kinds of life to evolve stably.”
One reason that this is a big deal is that stable, hydrogen-burning, M dwarf stars make up about 75% of all stars in the galaxy; therefore the probability that there are life-sustaining planets has just improved.
Update: One reader questioned why it was stated in my source article that "gravity dictates" that the planet is tidally locked. Good question! I looked in the scientific paper that announced the discovery (referenced below), and here is the relevant quote:
Also, the following statistics for Gliese 581g were cited, that it is "minimum-mass 3.1 M⊕ planet orbiting at 0.146 AU with a period of 36.6 days," showing that it is much closer to its star than Mercury is to our sun. Apparently, this characteristic has a close correlation with spin-synchrony.
Here is a short quote from a 2007 article in Astrobiology:
Comments from knowledgeable astronomers are invited. And thanks for asking, Murgatroyd666.
End update.
In his 1952 novel Foundation and Empire, Isaac Asimov called a planet like this a ribbon world:
Such a world invariably sounds uninviting to those who have not tried it, but there exist spots, strategically placed – and Radole City was located in such a one. It spread along the soft slopes of the foothills before the hacked-out mountains that backed it along the rim of the cold hemisphere and held off the frightful ice.
The warm, dry air of the sun-half spilled over, and from the mountains was piped the water-and between the two, Radole City became a continuous garden, swimming in the eternal morning of an eternal June.
Via Wired; also, read the scientific paper that announced this discovery at A 3.1 M⊕ Planet in the Habitable Zone of the Nearby M3V Star Gliese 581. Thanks to Winchell Chung for the tip and the reference on this story (you can also follow him @Nyrath).
“The threshold has now been crossed,” said astronomer R. Paul Butler of the Carnegie Institution of Washington, one of the planet’s discoverers, in a press briefing Sept. 29. “The data says this planet is at the right distance for liquid water, and the right mass to hold on to a substantial atmosphere.”
Gliese 581g is likely to have evolved to a spin-synchronous configuration, leading to one hemisphere of the planet lying in perpetual darkness. Joshi et al. (1997) presented three-dimensional simulations of the atmospheres of synchronously rotating planets in the habitable zones of M dwarfs and concluded that such tidally-locked planets can support atmospheres over a wide range of conditions, and despite constraints involving stellar activity, are very likely to remain viable candidates for habitability. Joshi (2003) presented a more sophisticated three-dimensional global atmospheric circulation model that expanded on the previous work of Joshi et al. (1997) and evaluated the climate of a spin-synchronous planet orbiting an M dwarf star. The results of that study reinforced the conclusions of Joshi et al. (1997) that synchronously rotating planets within the circumstellar habitable zones of M dwarf stars should be habitable.
While low mass stars have much longer lifetimes, their luminosity is so feeble that any planet would need to be nestled very close to the star to permit the possibility of having a surface temperature conducive to liquid water, which seems to be the sine qua non of life as we know it. In such small orbits [0.1–0.35 astronomical units (AU) for an M0 star, and closer still for smaller stars], any planet would become tidally locked to the star.
(From A Reappraisal of the Habitability of Planets Around M Dwarf Stars)
Radole was a small world – and, in military potential, perhaps the weakest of the twenty-seven. That, by the way, was another factor in the logic of the choice. It was a ribbon world – of which the Galaxy boasts sufficient, but among which, the inhabited variety is a rarity for the physical requirements are difficult to meet. It was a world, in other words, where the two halves face the monotonous extremes of heat and cold, while the region of possible life is the girdling ribbon of the twilight zone.
Scroll down for more stories in the same category. (Story submitted 9/30/2010)
Follow this kind of news @Technovelgy.| Email | RSS | Blog It | Stumble | del.icio.us | Digg | Reddit |
Would
you like to contribute a story tip?
It's easy:
Get the URL of the story, and the related sf author, and add
it here.
Comment/Join discussion ( 6 )
Related News Stories - (" Space Tech ")
First Trips To Mars Announced By Elon Musk
'I had determined that my first attempt should be a visit to Mars.' Percy Greg, 1880.
Lava Tubes On Moon And Mars
'...it never was built, or anything like that; it's just a big volcanic bubble.' - Robert Heinlein, 1957.
SpaceX EVA Spacesuit Tested By Polaris Dawn Crew
'Now, except for weight and heat, the same conditions prevail in this chamber as in space.' - Otto Willi Gail, 1929.
ESA To Build Moon Bases Brick By Printed LEGO Brick
'We made a crude , small cell and were delighted - and, I admit, somewhat surprised - to find it worked.' - John W. Campbell, 1950.
Technovelgy (that's tech-novel-gee!) is devoted to the creative science inventions and ideas of sf authors. Look for the Invention Category that interests you, the Glossary, the Invention Timeline, or see what's New.
Science Fiction
Timeline
1600-1899
1900-1939
1940's 1950's
1960's 1970's
1980's 1990's
2000's 2010's
Current News
California Fireman Arrested For Starting Fires
'Fire is bright and fire is clean.'
Robots Need A Better Sense Of Touch
'First, it rubbed my arms...'
MouthPad Supports Head And Tongue Tracking
'The operation that had transformed half his body... had located the control switchboard in his teeth.'
REALLY Remote Control Excavators
'It takes over a second for the signal to get to the Moon...'
Disney Helping Robots Dance
Dance, Robots, Dance.
Kolors Virtual-Try-On Predicted, And TRIED, By Harry Harrison
'Bill blinked at his own face under the plumed helmet...'
Detecting Drones In Ukraine With Candy (Sukork)
'...a robot detector circuit closed, activating a bell."
Nevada Will Use AI To Decide Worker Benefits
'They had screwed up and been blacklisted by Manna.'
Tether Cryptocurrency Flow Rate US$190Bn Per Day
'Alex did not find it surprising that people... were electronically minting their own cash.'
First Trips To Mars Announced By Elon Musk
'I had determined that my first attempt should be a visit to Mars.'
WaPOCHI Micro-Mobility Robot Follows Like A Pet With Your Bags
To follow the user like a pet while carrying their cargo!
Ultra-Realistic Robotic Arowana Robo-Fish
'Deveet unhooked his catch and laid it on the bank beside him. It was a metal fish.'
GITAI R1 Lunar Rover Like NASA Robonaut Centaur
'...waldoes in the screen followed in exact, simultaneous parallelism.'
Meshworm Soft Robot, With Peristaltic Crawling, Is Getting Better
'Seen close it was not completely flexible, but made instead of pivoted and smoothly finished segments.'
Mushroom 'Robot' Is Just A Start
'Some unknown race ... decided to help them out.'
Tesla Electric 'Giga Train' Operational In Germany
'...the cars are wedge-shaped at both ends.'
