Monday, December 18

Discovery: New Earth: A Thrilling Find For All Astronomers

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British television news recently featured the discovery of a new, potentially Earthlike planet, Gliese 581g. Good news indeed. So I had a read into it. Seems they have found about 7 or so planets revolving around a red dwarf star about 20 light years from us. As stars go, that’s quite local. Even better, Gliese 581g is located in the star’s “Goldilocks Zone”: just the right distance away from its sun to avoid being as hot as Venus or as cold as Mars. Furthermore, said planet is likely to be no more than twice the size of Earth, which ticks another box for being suitable to sustain life. So, one scientist at least rates the existence of life there as a “certainty”.

However, reading on, I find the “small print” less promising, if intriguing. Apparently the planet is “so close” to its sun that it is “tidally locked”. That means it has one “face” constantly bathed in sunshine, while the other face is always under the night stars (clouds permitting). Just like our Moon presents the same face to our Earth, this new planet always shows the same side to its sun. Think about what that means.

Surely anyone standing at the equator nearest the sun (on this new world) will be roasted. Anyone on the opposite side of that world would be frozen. The best chance of finding somewhere “equable” would be about half way between these extreme points: on a latitude where the sun is always low in the sky. I picture a “green belt” running like a halo round that hot central area where the sun is high up above.

Another item from the “small print”: unlike the Earth, this planet’s axis does not tilt. That means no seasons! So, no hint of seasons, and therefore years. The sun always in the same spot in the sky. No days as such, no nights, no dawns or sunsets. Indeed timeless. Do they sleep there? Do trees ever shed their leaves? Imagine it.

Let’s not forget, also that most stars are red dwarves. Red dwarves usually have relatively narrow Goldilocks Zones located very close to each star. Does that not mean that most planets orbiting red dwarves will be tidally locked too? So is the quest for Life really coming to a close?


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