Saturday May 12th… Dear Diary. The main purpose of this ongoing post will be to track United States extreme or record temperatures related to climate change. Any reports I see of ETs will be listed below the main topic of the day. I’ll refer to extreme or record temperatures as ETs (not extraterrestrials)😊. Here is today’s main climate change related topic:
Earth in the Goldilocks Zone
Some people know that if I had not done a dendrochronology science fair project for school in the 10th grade I may have selected astronomy as my field of study instead of meteorology and climatology. I remain a member of the Planetary Society and love to read about new NASA studies, especially on exoplanets, or those new worlds discovered outside our own solar system. What fascinates me is the study of the “Goldilocks Zone,” or physical habitable zone in which a planet, such as Earth, can sustain life. Of course, as far as we know Earth is the only planet that has life in the Universe, yet a multitude of suspected habitable exoplanets are discovered each year. My big questions are just how delicately placed Earth is in our own Goldilocks Zone and exactly how wide the zone is for our planet given its atmospheric composition? This post won’t specifically answer these questions given the current state of the science of astronomy but will begin to peel back the old proverbial onion some to garner better understanding of just how robust our environment is.
I’ve pulled up this diagram from Wikipedia depicting recently discovered exoplanets in relation to the solar system’s habitable zone:
A diagram depicting the Habitable Zone (HZ) boundaries, and how the boundaries are affected by star type. This new plot includes solar system planets (Venus, Earth, and Mars) as well as especially significant exoplanets such as TRAPPIST-1d, Kepler-186f, and our nearest neighbor Proxima Centauri b.
Notice that Earth is fairly close to the yellow line depicting the inner boundary of the “conservative” habitable zone. After doing more research I noticed this article:
It’s interesting that astronomers are using Venus with its runaway greenhouse effect as a measuring divice to try to determine how likely life would occur on certain exoplanets. Quoting from this article:
“We believe the Earth and Venus had similar starts in terms of their atmospheric evolution,” he said. “Something changed at one point, and the obvious difference between the two is proximity to the sun.”
Kane and his team defined the Venus Zone based on solar flux — the amount of stellar energy that orbiting planets receive. The outer edge of the zone is the point at which a runaway greenhouse effect would take hold, with a planet’s temperature soaring thanks to heat-trapping gases in its atmosphere. The inner boundary, meanwhile, is the distance at which stellar radiation would completely strip away a planet’s air.
The thinking is similar to that behind the “habitable zone” — the just-right range of distances from a star at which liquid water, and perhaps life as we know it, may be able to exist.
The dimensions of these astronomical zones vary from star to star, since some stars are hotter than others. In our own solar system, the Venus Zone’s outer boundary lies just inside the orbit of Earth, researchers said.
Future space-based instruments — such as NASA’s $8.8 billion James Webb Space Telescope, scheduled to launch in 2018 — will be able to analyze some exoplanets’ atmospheres, helping scientists refine the Venus Zone concept, researchers said.
“If we find all of these planets in the Venus Zone have a runaway greenhouse-gas effect, then we know that the distance a planet is from its star is a major determining factor. That’s helpful to understanding the history between Venus and Earth,” Kane said.
“This is ultimately about putting our solar system in context,” he added. “We want to know if various aspects of our solar system are rare or common.”
All of this leads me to believe that our climatic system is in a delicate, precarious situation since the Earth might be closer to the sun than is optimum for humans. Of course through paleontology we know that the Earth’s climate system is unstable, but life itself is very flexible having arisen as microbes about 4 billion years ago and surviving various mass extinctions of species from becoming a near ice ball to undergoing all polar ice melt to overcoming large impacts.
Will we push our climactic system beyond the bounds of human habitation? Scientists may find that due to Earth’s distance from the sun it is a lot easier to push the climate towards a greenhouse nightmare scenario than was previously thought…or not. We just don’t know since science is in its infancy regarding the study of exoplanets. I’ll revisit this subject as more expert science comes on line.
I’ll add ET data should I see some later today.
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