Planetary 'runaway greenhouse' more easily triggered, research shows

Planetary 'runaway greenhouse' more easily triggered, research shows

In the runaway greenhouse stage, a planet absorbs more solar energy than it can give off to retain equilibrium. As a result, the world overheats, boiling its oceans and filling its atmosphere with steam, which leaves the planet glowing-hot and forever uninhabitable, as Venus is now.

One estimate of the inner edge of a star's "habitable zone" is where the runaway greenhouse process begins. The habitable zone is that ring of space around a star that's just right for water to remain in liquid form on an orbiting rocky planet's surface, thus giving life a chance.

Revisiting this classic planetary science scenario with new computer modeling, the astronomers found a lower thermal radiation threshold for the runaway greenhouse process, meaning that stage may be easier to initiate than had been previously thought.

"The habitable zone becomes much narrower, in the sense that you can no longer get as close to the star as we thought before going into a runaway greenhouse," said Tyler Robinson, a UW astronomy postdoctoral researcher and second author on the paper. The lead author is Colin Goldblatt of the University of Victoria.

Though further research is called for, the findings could lead to a recalibration of where the habitable zone begins and ends, with some planets having their candidacy as possible habitable worlds revoked.

"These worlds on the very edge got 'pushed in,' from our perspective -- they are now beyond the runaway greenhouse threshold," Robinson said.

Subsequent research, the astronomers say, is needed in part because their computer modeling was done in a "single-column, clear-sky model," or a one-dimensional measure averaged around a planetary sphere that does not account for the atmospheric effect of clouds.

The findings apply to planet Earth as well. As the sun increases in brightness over time, Earth, too, will move into the runaway greenhouse stage -- but not for a billion and a half years or so. Still, it inspired the astronomers to write, "As the solar constant increases with time, Earth's future is analogous to Venus's past."

Other co-authors are Kevin J. Zahnle of the NASA Ames Research Center in Moffett Field, Calif.; and David Crisp of the Jet Propulsion Laboratory in Pasadena, Calif.

Welcome to SUV System Ltd!

SUV System Ltd is ISO 90012008 Certified electronics distributor with 10 years of experiences.

We have built up long term business relationship with about many companies which are stockers and authorized agents. we have a steady and reliable supply to meet customer's demands to the greatest extent .Confidently, we are able to lower your cost and support your business with our years of professional service.

SUV System Ltd is Electronic Components Distributor Supplies,Find Quality Electronic Components Supplies Products IC(Integrated Circuits),Connectors,Capacitor,Resistors,Diodes,Transistors,LED at Suvsystem.com. Sourcing Other Energy, Environment, Excess Inventory Products from Manufacturers and Suppliers at Suvsystem.com

Electronic Components distributor:http://www.suvsystem.com

Connectors Distributor:http://www.suvsystem.com/l/Connectors-1.html

IC Distributor:http://www.suvsystem.com/l/IC(Integrated-Circuits)-1.html

LED Distributor:http://www.suvsystem.com/l/LED-1.html

Capacitor Distributor:http://www.suvsystem.com/l/Capacitor-1.html

Transistor Distributor:http://www.suvsystem.com/l/Transistors-1.html

Resistor Distributor:http://www.suvsystem.com/l/Resistors-1.html

Diode Distributor:http://www.suvsystem.com/l/Diodes-1.html

SUV System Ltd insists on the managing faith ofsincereness,speciality,foresight, win-win,so we build up stable-relationship customers located all over the world, including the States, Europe, Argentina, UAE, Malaysia, Australia,and India etc

we are focus on the following fields,and hope we can help you.

Transistors Freescale Industrial IC IC(Integrated Circuits) VISHAY IC INFLNEON Diodes Multi-units Transistors Chip Inductors Electronic News ST Transistors Discrete Semiconductor Transistors Current Sensors Resistors TOSHIBA Transistors MAXIM IC LED AD IC Chip Ferrite Beads NS IC chip Filter saws Vishay resistors components Renesas parts IC Dialight LED Resistor Arrays Fleld Effect Transistors Fast Recovery Diodes NEC Diodes INTERSIL IC Resistor Networks Diodes TOSHIBA Diodes SANYO IC Low Ohmic Resistors Civil IC About US Texas Instruments(TI) IC ON Diodes IR Diodes YAGEO Resistors Chip Fuses Infineon Technologies Transistors
http://www.suvsystem.com/a/4496.aspx