Introduction
On October 2, 2003 scienctists were hunting for alien life that could relate to Goldilocks.
For many years they looked around the solar system. Mercury and Venus were too hot. Mars and the outer planets were cold. Only earth could be for life, only because our planet has liquid water, a breathable atmosphere, a suitable amount of sunshine perfect. Gliese 581g is an extra-solar planet candidate within a system that is only 20 light-years from Earth. First announced in 2010 as a planet three to four times Earth's mass in the habitable zone of its host star.
Task
By CALVIN W. JOHNSON, Ph.D., Assistant Professor, Department of Physics, San Diego State University Reprinted with the author’s permission from: http://physics.sdsu.edu/~johnson/writing/climate.html
Is Earth’s favorable climate an accident?
I’ve become acutely aware of climate since moving to Louisiana. The summers here are steamy and the winters fickle. Because Louisiana houses often lack sufficient in- sulation (due to some combination of poverty and optimism) thermostats work hard to moderate the temperature, running either the air conditioner or the heater con- stantly—sometimes both in the same day. Of course, compared to other locales, such as Alaska or the Sahara, Louisiana has a very mild climate.
Compared to other cosmic locales, the Earth itself has a very hospitable climate. Our neighboring planets, Venus and Mars, range the extremes in temperatures: the surface of Venus, at a temperature of 900o F, is hot enough to melt lead, while during Martian nights the tempera- ture drops to 220o F below zero.
Earth’s temperature is comfortably in-between: “just right,” like the bowl of porridge that Goldilocks ate. Thus planetary astronomers talk about the “Goldilocks problem”: is Earth’s favorable climate an ac- cident, or maybe an act of God? Is Venus just hot because it’s closer to the Sun, and Mars cold because it’s farther away?
The answer is no. The more you study any science, such as astron- omy, the more you find that the universe is far from random. There
View of Africa and Saudi Arabia from Apollo 17. NASA
are very deep reasons for the differences in climate among the terrestrial, or Earth-like, planets (as opposed to the Jupiter-like gas giants in the outer solar system), and I mean that literally. Beauty is only skin deep, but climate is not.
warming, but let me save that for later.)
We receive energy from our Sun in the form of light. The Sun is a ball of very hot gas, heated by ther- monuclear reactions at its core. All hot objects emit electromagnetic ra- diation, which includes radio waves, visible light, and X-rays, as well as ultraviolet and infrared radiation. The kind of radiation emitted de- pends on the temperature (the higher the temperature, the shorter the wavelength). For example, a piece of hot metal glows different colors at different temperatures. At “moder- ate” temperatures, metal glows a dull red; then, as it gets hotter, it will be orange in color, and then a brilliant yellow-white—about the same as the surface of the Sun, roughly 9000o F. If you could heat the metal even hotter, it would glow a bluish white, and eventually it would emit energy primarily in the ultraviolet.
But all objects emit electro- magnetic radiation, even relatively cold objects like rocks and people. Objects at room temperature emit infrared radiation, which is how some night-vision scopes see.
So the greenhouse effect works like this: the Sun, being very hot, emits visible light. The light from the Sun passes through the Earth’s atmosphere, which is transparent to visible light (that’s why our eyes evolved to be sensitive to this kind of electromagnetic radiation), and warms the surface of the Earth, which in turn reradiates the energy, now as infrared radiation, because the Earth’s surface isn’t as hot as the Sun.
T
to the Goldilocks problem. The first layer is like insulation, which keeps planets warm (and would keep my townhouse warm if it had any): the infamous greenhouse effect.
From all the debate about the greenhouse effect, it’s easy to get the impression that the greenhouse effect is a great evil. But that’s not true. The greenhouse effect makes Earth cozy. Without the greenhouse effect the Earth would be frozen, more than 60o F colder. I could use my cross- country skis in Louisiana, but that would be a high price to pay. The great bugaboo that has everyone worried, global warming, is actually a very small enhancement to the Earth’s overall greenhouse effect.
Write an expiation on what the Golilock Problem is?
Complete the following as provided to find more information about The Goldilock Zone.
- Go to http://science.nasa.gov/science-news/science-at-nasa/2003/02oct_goldilo…
- Write two paragraphs on the passage you have read.
- Complete the following Assignment attached.
Conclusion
- By now you should know some information about the Golilock Zone, please visit other websites for more fun!