NPR talks about Goldilocks planet that may hold keys to search for extra-terrestial life

NPR takes a look at a recently discovered planet, Gliese 581-g, which is located about 20 light-years from Earth. Scientists say that the planet is rocky, about Earth-sized, and lies within the temperate zone of star Gliese 581, which is a red dwarf.

Red dwarf stars have barely enough mass to become true stars. They are not quite failed stars but they are not very powerful stars, either. Red dwarf stars, it is believed, will be the last stars to go out before the universe (such as we know it) becomes a truly dark place.

Can Earth-like life dwell on such a planet? If it has an atmosphere and liquid water, perhaps. The solar radiation from the red dwarf star would be weaker than the solar radiation from our sun, Sol. But that radiation could still be deadly to folks like us if it’s not deflected or filtered.

Earth, because it has an active iron-nickel core — active meaning the core is still hot enough to swirl around — generates a large magnetic field that deflects a huge amount of solar radiation, thus protecting our atmosphere (and us) from certain doom.

Recent research shows us that Venus has lost a huge amount of water to the solar wind. Venus seems to be an inhospitable planet in large part because it is no longer geologically active. Venus’ incredibly weak magnetosphere is induced by the solar wind rather than generated internally by Venus’ core.

Mars’ own magnetosphere has pretty much shut down. There is no longer a planet-wide magnetic field, but rather many smaller magnetic fields scattered across the planet.

Our magnetic field provides us with fairly reliable compass points, beautiful light displays in the distant northern and southern polar regions, and acts as a space shield against dangerous radiation. Our atmosphere, protected by our magnetic field, gives us air to breathe, circulates water around our ecological supersystem, and shelters us from nasty rocks and debris that fall out of the sky.

In order to Earth-like life to flourish, a planet must be situated close enough to a star to experience warm temperatures like our own, possess liquid water, and hold on to its oxygenated atmosphere. But the planet needs to have at least one more key ingredient that neither Mars nor Venus have: a moon about the size of Luna.

To be more precise, the planet needs a tidal rhythm that tugs on it the way Luna tugs on Earth, or in some similar rhythmic way. We’re still figuring out the significance of Luna’s role in the drama of life-on-Earth, but many scientists now argue that had there been no moon — or perhaps too many moons — Earth might not have experienced life at all, certainly not life as we know it.

Thus in an age when scientists can point to formulas that calculate the probability of life arising on millions of planets around the galaxy — and they can point to hundreds of planets we’ve discovered in our vicinity that at least prove that stars commonly have planets — we still have to look at other factors in order to estimate the chances of life like ours arising elsewhere in the galaxy.

In fact, once you start to look at the precise requirements we have identified for Earth-like life, the classic Drake Equation begins to look quaint, perhaps even downright obsolete. It doesn’t begin to take all the necessary factors into consideration.

The Drake Equation was proposed by astronomer Frank Drake in 1961 (actually for the 1962 Green Bank conference). It looks rather simplistic in light of today’s cosmic science but in 1962 it produced some mind-staggering possibilities in the imaginations of an entire generation and even contributed significantly to the formation of and support for SETI (the Search for Extra-Terrestial Intelligence).

The Drake Equation is a mathematical toy without any real credibility. It allows you to blindly plug numbers into some variables and push out a calculation. Any set of numbers is as valid as another in this construction. In reality, we don’t have enough information about the galaxy’s structure to really be able to plug in reliable numbers. However, there are other factors that have to be taken into consideration that the formula isn’t cognizant of.

For example, there are probably sun-like stars near the center of the galaxy but it’s highly doubtful that they are accompanied by habitable planetary systems. At least, such systems could not be inhabited by creatures like us.

And then our own star, Sol, is no longer located near the stars that were formed in its nursery. That is, the stars that are near us now are very different from the stars that Sol was born with. Sol’s siblings might have planetary systems that are much more like Sol’s. If so, knowing that would tell us something important about the formation of stars and planetary systems. If Sol’s siblings have a variety of planetary systems — like the suns near Sol at the present time — that would also tell us something important about the formation of stars and planetary systems.

So far our science is barely able to identify possible Earth-sized planets orbiting stars in our vicinity. Actually, the smallest “Earth-sized planet” we think we have discovered to date is still much larger than Earth. Its greater mass would create more gravity than we are used to. How much does gravity play into the evolution of life? We already know that if we spend long periods of time in low gravity our muscles and bones experience decay (or entropy).

As we add items to the checklist of ingredients that are probably required to produce a world that is truly like Earth, we narrow the odds of finding another Earth-like world even though our advancements in science have increased the odds of finding other Earth-similar worlds.

The cosmic five-hundred-dollar question comes down to this: just how much like Earth does a planet have to be in order to produce Earth-like life? The narrower the bandwidth of tolerance for divergence from the standard that Earth has set, the less likely we will find other Earth-like life in the galaxy.

In other words, science has so far gone farther down the path toward proving that we are more likely unique than common, but that doesn’t mean the matter is even close to be resolved. We are still in our infancy in terms of understanding that portion of the universe that lies within our immediate visual range — and we’re orders of magnitude farther away from understanding for yet more remote parts of the universe.

Time will tell if we are truly alone in the universe, or — if not alone — we are essentially unique.

That is why we need to study this Goldilocks planet. Understanding it better will help us understand where and what we are better — and also may shed some light on our chances of finding other Earth-like worlds and, possibly, signs of Earth-like life.