Five planets, including one in the habitable zone of the very nearby star, Tau Ceti have been detected. With planets now tentatively discovered around three very close stars, Alpha Centauri B, Epsilon Eridani, and now, Tau Ceti, the case for extrasolar planets being very plentiful is looking better and better.
The potentially habitable planet is thought to have a mass of about 4.3 times that of Earth. If the planet is Earth-like in its composition, that indicates a diameter of around 12,000 miles, or half again as large as Earth. Such a planet would have a surface gravity about twice that of Earth.
Tau Ceti is thought to be approximately 5.8 billion years old, somewhat over a billion years older than our Sun. This suggests ample time for life to have begun, and progressed to a point well beyond that on Earth.

I have read, elsewhere, some doubts expressed about the viability of intelligent life in a world with twice the surface gravity that we consider normal. I suspect that life is sufficiently adaptable to cope with this, though. Beings evolved in such a world would probably be more sturdily built and stronger than we are. They might consider us abnormally weak and spindly, and so we would be if we visited such a planet.

I hope extraterrestrial life exists, But! Nothing Is Impossible Just Highly Improbable.


Possible habitable zone planet is a mere 12 light years away

Most of the exoplanets we've discovered thus far have been found because they're easy to spot—Jupiter-sized giants orbiting close in to their host stars. But the Kepler mission has been providing a huge catalog of exoplanets and with it we've obtained a very different perspective, finding that planets in general are common and most of them are far smaller than the gas giants first identified. This new perspective has raised the prospect that we can identify some orbiting nearby stars, following identification with direct observations searching for signs that the planet's atmosphere is shaped by life.

_____________________
The universe wastes nothing, it's simply transferred.

I also read that article, quite interesting...

---

rOZZ
Music
Pictures

Some elements and compounds that might be detected in an exoplanet's atmosphere, that could indicate life are: oxygen, water vapor, carbon dioxide, ozone, and methane. The latter three would probably be found in very minute proportions, hundredths of a percent, or less.
It's interesting to speculate what trace gases might be found specifically due to an extraterrestrial civilization. Our own civilization causes an excess of carbon dioxide, ozone and methane due to industrial processes, fuel combustion. and large-scale agriculture.
One might speculate that a sufficiently advanced civilization could seek to control its climate, by altering the mix of trace gases in a planet's atmosphere. We know little of such possibilities, yet already realize that methane, for example, is an especially potent agent of atmospheric warming, much more so that even carbon dioxide.
Conceive of a planet about to enter an an ice age. The resident civilization releases extra methane into the atmosphere, forestalling this, and saving themselves from a hugely disruptive problem. They would also be creating a marker of their civilization, apparently detectable at stellar distances, given astronomical technology we will soon have at our disposal. If we some day detect more methane in a planet's atmosphere than can be readily explained by a primitive flora and fauna, we should give consideration to this scenario.

I think that the ability to detect in detail the gases present in an exo planet's atmosphere will prove to be one of the best means of finding life, either intelligent or not. I also think that now that astronomers are finding planets orbiting stars that previously were thought not to have planets the probability of other civilizations existing in our galaxy has risen greatly. Whether or not we will ever encounter one or more of them I think depends on whether we will ever find a way around the speed of light.

---

Bob DeWoody

My motto: Never do today what you can put off until tomorrow as it may not be required. This no longer applies in light of current events.

A good thing (sometimes) technology keeps on improving!

Three habitable zone planets discovered around red dwarf

---

rOZZ
Music
Pictures

Thanks for that, Julie. A very good find. These three planets seem to orbit remarkably closely to each other. I wonder how they would interact gravitationally. Interesting to hear this point addressed by a good dynamicist.
All three planets appear to be near enough their primary to be tidally locked; to always present nearly the same face toward the star. This doesn't necessarily rule out life, though. A large planet with a substantial atmosphere and good circulation might distribute heat well enough to make the annular zone, equidistant from the sub-stellar, and anti-stellar points, temperate. Winds driven by heated air in the torrid zone could travel to the frigid zone, opposite, and then return, in a planet-wide toroidal convection cell.
Signs of intelligent life on one of these planets, such a artificial lights or radio waves could probably be readily detected on either of the other two. This could act as a very strong stimulus to the development of interplanetary space travel, if any two, or all three of the planets are host to intelligent life.