Exoplanet (for astronomers) is simply any planet not in this solar system. Are any in that “goldilocks zone”, which give the capability of harboring life as we know it? Can we even see it, given its immense distance?
One must define “goldilocks zone” properly: [Habitable zone - Wikipedia, the free encyclopedia ]. That zone is considered the habitable area just far enough away from its sun, where it’s warm enough life can flourish, but not too cold to freeze water.
Astronomer Michael Hart’s computer simulations describe a habitable planet in the “goldilocks zone”. Its orbit must be almost circular, and must make the right sized orbit. Calculations indicate a 5% smaller orbit point to a runaway “greenhouse effect”, or a 1% larger orbit would have resulted in a glacier effect—the freezing of all oceans.
The solar system must be free of large planets with elliptical orbits, which would eject or destroy other planets. Large planets with circular orbits are needed to clear out rogue asteroids that would strike inner planets much more frequently.
An inhabited planet has to be large enough to hold an atmosphere, while small enough so its gravity doesn’t crush inhabitants. The planet must have a moderate temperature. The planet must have a mass between 0.85 and 1.33 of earth’s mass, or within 2 billion years temperature variations would render the planet uninhabitable. [Extraterrestrials, Where Are They?, Second Edition, Edited by Ben Zuckerman and Michael Hart (Cambridge, England: Cambridge University Press, 1995), p. 217].
More importantly, a habitable planet must have some mechanism to keep CO2 from disappearing from the atmosphere. Liquid water begins a chain reaction depleting the atmosphere of CO2 [Ron Cohen, “Interplanetary Odyssey”, Science News (September 28th, 1996), p. 205].
Parts of earth’s surface continually sink where carbonate decomposes to CO2. It then recycles to the surface from volcanic activity, where it refills the atmosphere. We haven’t observed any other planet with similar tectonic activity.
Most extrasolar planets are too distant to detect their weather. Because exoplanets are invisible to the telescope “eye”, any atmosphere is examined by its infrared light, or heat. Infrared measurements are used to map the temperature of the entire surface.
But an observable exoplanet has got to be a transiting planet---it has to cross directly in front and behind its star when viewed from Earth. As an extrasolar planet passes in front of its star, it blocks out a small fraction of the star's light, and a host of information about the exoplanet can be learned: size, temperature, orbit, etcetera. Because of their location in the plane of sight relative to their orbited star, billions of exoplanets cannot be detected yet.
Over 300 extrasolar planets have been located and measured by this method, and are called “hot Jupiters” for a reason. Jupiter has many characteristics similar to exoplanets. It is a gas giant, with a crust far beneath the surrounding gas.
The Coriolis Effect cause cyclones and anti-cyclones on Earth. Greatly magnified on Jupiter, these cyclones have a revolution 2.5x faster than Earth’s cyclones. Sheer distance makes cyclones on any exoplanets invisible.
Jupiter has many atmospheric disturbances, with stronger ones absorbing the weaker ones. This may explain the size of the largest spot on Jupiter---the Great Red Spot (GRS). Man has observed this spot for almost 400 years, or as long as the telescope existed. Over two earths would fit within this storm.
The GRS is anti-cyclonic in Jupiter’s southern hemisphere, and high pressure. It seems to be about 5 miles higher than other cloud tops. A hurricane on earth rotates clockwise, being low pressure. GRS however, has been shrinking at 230 miles/yr. But at half the size of the GRS, Jupiter also has the “Oval BA”, which appeared in 2000. This was the result of three smaller spots merging. Scientists determined the Oval BA has winds up to 384 miles per hour.
Jupiter's Three Red Spots (5/23/08)
Credit NASA, ESA, M. Wong, I. de Pater (UC Berkeley), et al.
All three spots are in this image made on 5/9/98 (Hubble Space Telescope). Jupiter's spots are probably indicative of large scale climate change. It is getting warmer near the equator. The GRS is also warmer. “Warm”, in this case, translates to -250 oF. Surrounding temperatures are colder at -256 oF. Even that difference generates questions concerning global warming. Changes in Jupiter's weather give rise to debate over perceived climate change on earth.
In 1998, scientists decided to launch an atmospheric probe into Jupiter . It finally crumpled in 23x higher pressure than earth’s.
On Earth, anticyclones usually indicate fair weather. Jupiter's anticyclones are also high pressure centers, while cyclones are low pressure. Jupiter is shrinking in size due to gravity. Actually a heat source, it radiates 1.6x more energy than it receives from the Sun.
Juno launched from Cape Canaveral on 8/5/2011, to begin its five-year journey to Jupiter. In 2016, many questions will be answered from Juno’s Jupiter encounter.
Is climate change a normal result of CO2 activity on Jupiter? Obviously not because of CO2, with essentially “zero” content. Runaway “greenhouse effects” can occur with a 5% smaller orbit in a “goldilocks zone”, but it’s never due to CO2. It’s always due to orbiting distance.
One almost has to be an exo-atmospheric-meteorologist to understand planetary weather. Likely, the science may have changed in the past few years.
Kevin M. Roeten can be reached at firstname.lastname@example.org.