. 24/7 Space News .
Hot Windy Nights

illustration only
by Staff Writers
Tacoma WA (SPX) Jan 18, 2007
Earth's inhabitants are used to temperatures that vary, sometimes greatly, between day and night. New measurements for three planets outside our solar system indicate their temperatures remain fairly constant -- and blazing hot -- from day to night, even though it is likely one side of each planet always faces its sun and the other is in permanent darkness.

The reason apparently is supersonic winds, perhaps as strong as 9,000 miles an hour, that constantly churn the planets' atmospheres and keep temperatures on the dark side from plunging.

The planets, gas giants similar in size to Jupiter, were discovered in the last decade orbiting stars about the same size as our sun and less than 150 light years from Earth. All of them orbit within about 5 million miles of their stars, far less than Mercury's distance from our sun.

Astronomers have wondered whether planets orbiting so close to their stars but with one side in constant daylight and the other permanently dark would exhibit sharp temperature differences between the day side and the night side.

For the three planets in this study, the temperatures appear to be constant, likely because of the strong winds that mix the atmosphere planetwide, said Eric Agol, a University of Washington assistant professor of astronomy and co-author of a poster presenting the findings at the American Astronomical Society national meeting in Seattle.

"We can't say for sure that we've ruled out significant day-night temperature differences, but it seems unlikely there is a very big contrast based on our measurements and what we know about these systems," said Agol, who is lead scientist for a project using the Spitzer Space Telescope to measure the temperature properties of extrasolar planets.

Agol and colleagues Nicolas Cowan, a UW astronomy doctoral student and lead author of the poster, and David Charbonneau of the Harvard-Smithsonian Center for Astrophysics measured infrared light from each of the planetary systems at eight different positions in their orbits in late 2005

They measured the thermal brightness of the systems when the planets' day sides faced the Earth, when the night sides faced the Earth and at various phases in between. They detected no infrared brightness variations in any of the systems, suggesting there are not big differences in temperatures on the day and night sides.

Instead the planets appear to have a fairly uniform temperature of about 925 degrees Celsius, or about 1700 degrees Fahrenheit.

"If heat from the parent star is carried to the dark side, then the overall temperature would be lowered somewhat because the heat is being distributed across the planet," Agol said. "Some theorists believe that supersonic winds are responsible for recirculating the heat."

Measuring the planets' temperatures is a painstaking process because a planet's radiation is drowned out by the light from its host star. Even when a planet goes behind the parent star and disappears completely from view, the decline in light from the entire system is almost imperceptible, on the order of 0.25 percent, Agol said. Making the observations requires precise calibration and light measurements.

The three planets are 51 Pegasi, about 50 light years from our sun, HD179949b about 100 light years distant, and HD209458b about 147 light years away. A light year is about 5.88 trillion miles. In 1995, 51 Pegasi became the first planet orbiting another star to be discovered. Since then numerous planets -- gas giants the mass of Jupiter or larger -- have been observed from Earth.

Most orbit very close to their stars. A common theory is that they formed far away from their stars, perhaps in about the same position as Jupiter is to our sun, and then migrated close to their stars. Their distance makes it difficult to gather much direct data about the planets.

To date no Earth-sized planets have been reported orbiting other stars like our Sun. However, the processes that affect the planetary environments of extrasolar gas giants can still help astrobiologists understand what makes a planet habitable (or inhabitable), and to better define what is known as the 'habitable zone' around distant stars.

Agol noted that the planets probably have the same side always facing the star because they are so close to their parent stars. The effect is the same as the Earth has on the moon, which has had its rotation slowed so much by Earth's gravity that the same side always faces Earth.

"These planets are so close to their host stars that the tidal forces are enormous, a few thousand times as strong as on Earth," he said. "The tides are so strong and form a bulge that distorts the planet so much that the orbit is slowed by the star's tug on the tidal bulge."

Related Links
University of Washington
Stellar Chemistry, The Universe And All Within It



Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News


Checking Out The Stellar Neighborhood
Atlanta GA (SPX) Jan 16, 2007
Ancient astronomers logically focused their efforts on the brightest stars, the ones they could see in the night sky. Many modern astronomers, aided by ever-more-sensitive telescopes, have investigated objects that are unimaginably distant and ancient, phenomenally bright and powerful.







  • Starchaser Industries Wins European Space Agency Contract
  • Russia And Europe Join Forces In Space
  • Europe Forges Long-Term Strategy For Space Exploration
  • Eileen Collins: An Astronaut's Endless Endeavor

  • Europe Faces Crunch Decision Over Mars Rover Mission
  • Opportunity Finds Another Meteorite
  • Spirit Continues To Test New Computer Smarts
  • MRO Conducts Details Survery Of Mars Pathfinder Landing Site And Surroundings

  • Sea Launch Prepares For NSS-8 Mission
  • Launch Window To Open At Poker Flat Research Range
  • All Four Satellites In Healthy Condition After PSLV Launch
  • India Tests Technology For Space Vehicles

  • Egypt Plans First Remote Sensing Satellite
  • Japanese Government Initiates Space-Borne Hyperspectral Payload Program
  • US Climate Satellites Imperiled By Low Federal Funding Say EO Scientists
  • Cartosat-2 Camera Tested

  • Jupiter Encounter Begins For New Horizons Spacecraft On Route To Pluto
  • New Horizons in 2007
  • Pluto Sighted For First Time By New Horizons From Four Billion Kilometers Away
  • Making Old Horizons New

  • Hot Windy Nights
  • Checking Out The Stellar Neighborhood
  • Interactive Binary Stars Show Signs Of Induced Hyperactivity
  • Dust Around Nearby Star Like Powder Snow

  • Moon May Be More Like Earth Than Thought
  • Japan Set To Cancel Delayed Moon Probe Mission
  • Copernicus And the Wild Goose Chase
  • British Plan For Solo Moon Missions Unlikely

  • ESA Chief Says Galileo Test Problems Are Being Fixed
  • One year of Galileo signals
  • L-3 Wins Contract For Three Dimension Locator Systems For First Responders
  • BAE Systems Demonstrates Passive Geo-location Technology

  • The content herein, unless otherwise known to be public domain, are Copyright 1995-2006 - SpaceDaily.AFP and UPI Wire Stories are copyright Agence France-Presse and United Press International. ESA PortalReports are copyright European Space Agency. All NASA sourced material is public domain. Additionalcopyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by SpaceDaily on any Web page published or hosted by SpaceDaily. Privacy Statement