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No signs of life yet

The question of whether life exists on other planets will always remain a curiosity as we continue venturing into space. Movies like "E.T." and "Alien" are just a couple examples of our fascination with such an idea. 

NASA, as our government space agency, is obviously curious as well. But we could be a step closer to answering such questions as NASA has found the first Earth-Size planet in the 'habitable zone' of another star. 

According to NASA, the Kepler Space Telescope found an Earth-sized planet orbiting a star in the habitable zone, which is the range of distance from a star where liquid water might collect on the surface of an orbiting planet -- meaning the possibility of life. 

The new planet has been dubbed Kepler-186f, and it is about 500 light-years from Earth in the constellation Cygnus. It orbits a star -- which is classified as an M dwarf, or red dwarf -- half the size and mass of our sun.

Kepler-186f orbits its star once every 130-days and receives one-third the energy from its star that Earth gets from the sun. This puts it near the outer edge of the habitable zone. 
 
The brightness of its star at high noon is only as bright as Earth's sun appears about an hour before sunset. Further, NASA isn't quite sure yet, but it believes Kepler-186f's surface rocky.
 

A sketch of Kepler-186f [SOURCE: NASA]

Kepler-186f isn't alone over there, though. It has four companion planets, called Kepler-186b, Kepler-186c, Kepler-186d, and Kepler-186e. They make their way around their sun every four, seven, 13, and 22 days respectively, and they're too hot for any life to exist on them. 
 
Size is key here. While planets have been discovered in the habitable zone before, they haven't been the same size as Earth, which makes it harder for us to understand fully. The four companion planets, for example, all measure less than 1.5 times the size of Earth. Also, previously discovered planets in the habitable zone were were at least 40 percent larger in size than Earth. 

With Kepler-186f being about the same size as Earth, we can have a clearer idea of behaviors, topography, etc. But as of right now, its mass and composition are unknown. 

Unfortunately, whether it contains other life is also unknown at this time. But it's always a worthy consideration when stumbling upon new planets in what are considered "habitable" areas. 

"The discovery of Kepler-186f is a significant step toward finding worlds like our planet Earth," said Paul Hertz, NASA's Astrophysics Division director at the agency's headquarters in Washington. "Future NASA missions, like the Transiting Exoplanet Survey Satellite and the James Webb Space Telescope, will discover the nearest rocky exoplanets and determine their composition and atmospheric conditions, continuing humankind's quest to find truly Earth-like worlds."

Source: NASA



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RE: Absurd Methodology
By dgingerich on 4/18/2014 4:48:09 PM , Rating: 2
Something like the CE would probably be water-ice based and develop in an Oort cloud area.

Honestly, we use Earth as a template for finding other planets with possible life because we really don't know enough to look for life under other conditions.

This planet has a year equal to 130 of our days, and may have a much slower rotational period than Earth thanks to its close orbit. It is also around a much smaller and redder star than ours, and would not work well for what plant life we know about. Photosynthesis would be much less efficient with that wavelength of light. We wouldn't have to worry about sunburn, though.

I hope they find a Earth sized planet in the habitable zone of a blue giant. It would probably have about a 10,000 day year and be covered with superflora. However, the ultraviolet radiation would be extremely harsh. I think it'd be fun.


RE: Absurd Methodology
By Solandri on 4/18/2014 5:32:25 PM , Rating: 2
quote:
It is also around a much smaller and redder star than ours, and would not work well for what plant life we know about. Photosynthesis would be much less efficient with that wavelength of light.

Actually, the chlorophyll molecules used for photosynthesis are most efficient in the blue and red spectrum. They're rather poor at green, where our sun's light is strongest. That's why leaves appear green - it's the color that's been absorbed the least by chlorophyll.


RE: Absurd Methodology
By WLee40 on 4/19/2014 5:59:40 PM , Rating: 3
Actually, our sun is strongest at yellow, not green. Green is the wavelength our eyes are most sensitive to.


RE: Absurd Methodology
By maugrimtr on 4/22/2014 11:24:39 AM , Rating: 3
quote:
Using everything about the planet Earth as a blueprint to find other life is incredibly short-sighted in my opinion. It ignores the possibility that life evolved elsewhere under radically different conditions.

As far as I'm concerned, the playing field is wide open. There is no such thing as a "habitable zone". Even on Earth we have life where it was previously thought to be impossible to exist.


Nematodes (a sort of worm) and bacteria have been located miles beneath the Earth's surface. We simply haven't gone any deeper to see just how far down the...sorry!...rabbit hole...life lives. Other microbes have been found flourishing around underwater volcanic vents where water temperatures can reach almost 300 degrees F. You want alien lifeforms? We have plenty of them. We humans are outnumbered by them millions to one.

Take a look at the magnificently alien creature called a Tardigrade. It was discovered in the 1770s, a tiny little 8 legged animal about 0.5 mm in length when fully grown: http://en.wikipedia.org/wiki/Tardigrades

quote:
Tardigrades can withstand temperatures from just above absolute zero to well above the boiling point of water, pressures about six times greater than those found in the deepest ocean trenches, ionizing radiation at doses hundreds of times higher than the lethal dose for a human, and the vacuum of outer space. They can go without food or water for more than 10 years, drying out to the point where they are 3% or less water, only to rehydrate, forage, and reproduce.


Do not underestimate just how alien Earth really is. Scientists are not shortsighted, they have spent a lot of time researching extreme life. Tardigrade are about as extreme as it gets - though their impressive survivability isn't forever - they can survive vacuum for about a week (I think). These amazing creatures certainly do live anywhere.

quote:
I tend to agree, but maybe that's because I'm a Trek fan, and I believe in the possibility of silicon-based lifeforms, etc. (No, not the type that reside in LA, south-beach or Rio).


Unfortunately, this is science fiction. Where Carbon can bond to a huge range of other atoms, Silicon is far more limited. Your DNA, proteins, enzymes, sugars? All the result of Carbon's incredible flexibility to create a massive range of molecules. Silicon does not have the same range - it's an unavoidable fact of basic chemistry. Another unavoidable fact is that long chained Silicon molecules are simply not that stable - and spontaneously decompose to boot.

Silicon is just a really bad substitute for Carbon. 90% of the Earth's crust is silicate minerals (no kidding - Silicon is literally as common as dirt!). Yet life still chose to use a far rarer element, Carbon, instead.

quote:
This planet has a year equal to 130 of our days, and may have a much slower rotational period than Earth thanks to its close orbit. It is also around a much smaller and redder star than ours, and would not work well for what plant life we know about. Photosynthesis would be much less efficient with that wavelength of light. We wouldn't have to worry about sunburn, though.


There's another possibility. With the abundance of sunlight at the Sun's wavelengths, photosynthesis on Earth might not be as efficient as it could be. The Sun has a limited useful range (you need specific wavelengths so maybe 40%+ of sunlight is actually unusable by plants), usable light will reflect off leaf surfaces, plants still need to commit leaf area to intaking CO2 and expelling O2, etc., instead of photosynthesis and so on.

Lots of room for evolution to improve given a different star with different priorities for life compared to Earth.


RE: Absurd Methodology
By asgallant on 4/19/2014 11:57:05 AM , Rating: 2
Blue giants don't last long enough for any significant life to evolve - and probably no life at all, given that giant main-sequence stars have life spans on the order of millions of years, and it took billions of years before life could arise here. Even if life did arise, it likely wouldn't have sufficient time to evolve beyond the equivalent of early single cell organisms here or Earth before the star self-destructs.


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