Galaxy Full of Other Earths

Well, maybe it matters to listen to TED Talks…

Seems that the population of planets in the Galaxy is dominated by smaller sized planets, 2 x Earth or smaller.

Kepler Finds Lots of Earth Like Planets

This is from back about June of 2010, so I’m getting to it a bit late, still, it matters.

Only thing is, this news was leaked in a TED Talk instead of officially announced. Would have been nice to have been officially recognized. Oh well, ‘all in good time’ I guess.

“The Galaxy is rich in small Earth like planets” … about “100 Million planets have habitable potential”.

More in the story at:

http://news.discovery.com/space/kepler-scientist-galaxy-is-rich-in-earth-like-planets.html

The TED Talk is by Dimitar Sassilov and the major point he is trying to make is that the progress in ‘synthetic biology’ where we make processes in the lab similar to how life formed is moving toward the answer of ‘how much life and it is like us?’ from one direction while ‘how many earth like planets?’ is moving toward that answer from another. Toward the end he makes a point about “If we are to be good stewards” that wasn’t real clear to me ( he wants us to ‘do it’ but it’s a bit unclear to me what we are to do… be ‘stewards’ or find life or…) But my sense of it is that he’s saying the probability of other life in the galaxy is now quite high, and we, though a small planet, have a long history of live, so we ought to protect it better. ( I think…)

At any rate, the Drake Equation is slowly getting filled out with answers, and the answers all tend to point toward a Galaxy full of life. (Though SETI implies they don’t use the radio much…)

Double Your Pleasure

Then, last September, NASA announced a planet found in a binary star system. This is a ‘big deal’ as some folks had asserted the instability of gravitational forces around binaries might prevent or reduce planet formation. As most starts are binaries, it’s important to know they can have planets too. (To me it was always a no brainer that they would be fine. Look at Jupiter, Saturn, and all their moons. Just ‘scale it up’ a bit and we would have a binary system right here…). What makes this announcement interesting, though, was that the planet was found to be mutually orbiting both stars. Kind of like finding a planet out in the Kuiper Belt that’s orbiting the center of mass of the solar system and doesn’t really care if Jupiter were glowing…

http://science.nasa.gov/science-news/science-at-nasa/2011/15sep_doublesuns/

“This discovery confirms a new class of planetary systems that could harbor life,” Kepler principal investigator William Borucki said. “Given that most stars in our galaxy are part of a binary system, this means the opportunities for life are much broader than if planets form only around single stars. This milestone discovery confirms a theory that scientists have had for decades but could not prove until now.”
[…]
Astronomers further observed that the brightness of the system dipped even when the stars were not eclipsing one another, hinting at a third body. The additional dimming in brightness events, called the tertiary and quaternary eclipses, reappeared at irregular intervals of time, indicating the stars were in different positions in their orbit each time the third body passed. This showed the third body was circling, not just one, but both stars, in a wide circumbinary orbit.

New News?

So that’s all old news. Any “new news”?

From NASA on 26 Jan 2012:

http://www.nasa.gov/home/hqnews/2012/jan/HQ_12-032_Kepler_23-33.html

RELEASE : 12-032
NASA’s Kepler Announces 11 Planetary Systems Hosting 26 Planets

MOFFET FIELD, Calif. — NASA’s Kepler mission has discovered 11 new planetary systems hosting 26 confirmed planets. These discoveries nearly double the number of verified planets and triple the number of stars known to have more than one planet that transits, or passes in front of, the star. Such systems will help astronomers better understand how planets form.

The planets orbit close to their host stars and range in size from 1.5 times the radius of Earth to larger than Jupiter. Fifteen are between Earth and Neptune in size. Further observations will be required to determine which are rocky like Earth and which have thick gaseous atmospheres like Neptune. The planets orbit their host star once every six to 143 days. All are closer to their host star than Venus is to our sun.

“Prior to the Kepler mission, we knew of perhaps 500 exoplanets across the whole sky,” said Doug Hudgins, Kepler program scientist at NASA Headquarters in Washington. “Now, in just two years staring at a patch of sky not much bigger than your fist, Kepler has discovered more than 60 planets and more than 2,300 planet candidates. This tells us that our galaxy is positively loaded with planets of all sizes and orbits.”

Kepler identifies planet candidates by repeatedly measuring the change in brightness of more than 150,000 stars to detect when a planet passes in front of the star. That passage casts a small shadow toward Earth and the Kepler spacecraft.

Each of the new confirmed planetary systems contains two to five closely spaced transiting planets. In tightly packed planetary systems, the gravitational pull of the planets on each other causes some planets to accelerate and some to decelerate along their orbits. The acceleration causes the orbital period of each planet to change. Kepler detects this effect by measuring the changes, or so-called Transit Timing Variations (TTVs)

Planetary systems with TTVs can be verified without requiring extensive ground-based observations, accelerating confirmation of planet candidates. The TTV detection technique also increases Kepler’s ability to confirm planetary systems around fainter and more distant stars.

Five of the systems (Kepler-25, Kepler-27, Kepler-30, Kepler-31 and Kepler-33) contain a pair of planets where the inner planet orbits the star twice during each orbit of the outer planet. Four of the systems (Kepler-23, Kepler-24, Kepler-28 and Kepler-32) contain a pairing where the outer planet circles the star twice for every three times the inner planet orbits its star.

“These configurations help to amplify the gravitational interactions between the planets, similar to how my sons kick their legs on a swing at the right time to go higher,” said Jason Steffen, the Brinson postdoctoral fellow at Fermilab Center for Particle Astrophysics in Batavia, Ill., and lead author of a paper confirming four of the systems.

Kepler-33, a star that is older and more massive than our sun, had the most planets. The system hosts five planets, ranging in size from 1.5 to 5 times that of Earth. All of the planets are located closer to their star than any planet is to our sun.

The properties of a star provide clues for planet detection. The decrease in the star’s brightness and duration of a planet transit, combined with the properties of its host star, present a recognizable signature. When astronomers detect planet candidates that exhibit similar signatures around the same star, the likelihood of any of these planet candidates being a false positive is very low.

“The approach used to verify the Kepler-33 planets shows the overall reliability is quite high,” said Jack Lissauer, planetary scientist at NASA Ames Research Center at Moffett Field, Calif., and lead author of the paper on Kepler-33. “This is a validation by multiplicity.”

These discoveries are published in four different papers in the Astrophysical Journal and the Monthly Notices of the Royal Astronomical Society.

Notice how many of these were stated as being in orbits “closer to the star than” and various limits like “any planet” in our system or ‘Venus’ or… That’s because they are detecting transits, so a planet with an orbital period of 100 years is going to take several years to make a transit. The planets far from their suns will take a lot longer to find. THAT means this is a lower bound on planets in those systems, not an upper bound.

I also note in passing that we are seeing orbital resonance in those systems, too. This is nice in that it confirms that our system with lots of orbital resonance is the norm, not some oddball.

So Much Space

With so much space, and so many stars, and so many of them full of planets (now being confirmed) and lots of them in the habitable zones (numbers to rise over time as longer orbital period objects are found) and the chemicals of life being found scattered all over the solar system (and spontaneously forming in the lab): Heck, they might even start to suspect that life will be about as common as planets that can support it.

Next thing you know, they will start to figure out that some of it will have existed for a few Billion years before ours got started. That during that time it will have got off its rock and moved on into space. And even at a fractional percent of the speed of light, some of them will have been wandering off to look at other interesting rocks with life-like signatures on them…

I suspect we are slowly approaching the point where we can admit:

1) We are not alone.
2) They are smarter than we are.
3) They have been here, but see no reason to talk to us much.

I’m pretty sure our historical accounts of beings from the sky and of alien visitors have truth in them. IF that is true, we can see how they reacted. Kind of like our VISTA and Peace Corps. A few folks who run off to some hole somewhere and try to make the folks lives better for a while, teach them a few things, then head back home. Some other groups looking to get a Ph.D. in “Alien Earth Biology” establishing ‘blinds’ so they can observe the primitive culture.

Yes, the “Ancient Aliens” ideas. Look, we’ve got written records. The interpretation as Gods and Angels only came later, in many cases.

So think about it for a minute. In a galaxy full of planets and life, with Nova and Supernova events on a fairly regular schedule, sitting on your original rock waiting to become extinct is not going to be an attractive option for any intelligent species. (Though most of humanity is happy with it… something to ponder…)

Once they decided to head into space, why hang around any one star? Especially once you know it, or one near it, is likely to explode? So there will be generational ships (if not faster) wandering around looking for nice long lived yellow stars to visit. Picking up asteroids and space rocks for building materials will be boring after a while, too. At that time, the occasional scout ship sent off on a study party to ‘That interesting primitive tribal life’ over there… well, it’s just going to happen.

One of the easier ways to do it will be gravity assisted orbits. Lots of loops and long approaches. So maybe “Nemesis” isn’t a planet as we know it. Perhaps it is just a very large generational ship in a ‘few thousand year’ highly elliptical orbit. One that conserves some of that valuable velocity (should they decide to visit somewhere else) and keeps them away from the local riff-raff most of the time, but occasionally brings them in for a pass by the resources mines of the asteroids and to pick up some more plasma and hydrogen for the fusion reactors.

Describe such a craft to a primitive culture without the concept of ‘generational ship’, and they will record it as a planet. Describe your fusion reactors as being like the sun, and they will picture a wandering star.

Such a visiting generational ship could explain a lot. The long periods between ‘interventions’. The low contact rates (just a few folks from scout ships most of the time, larger contacts on very long cycles). Tendency to indifference, really. (A bit of a ‘humanitarian’ sharing of a few good ideas, but mostly hands off with ‘the natives’).

Is this “Crazy Talk”? I don’t think so. It is just reacting to the numbers and the highest probabilities. We now KNOW the galaxy is crammed with planets. We now KNOW that life is not hard to form and the building blocks both form spontaneously and are found floating around the solar system. We now KNOW that other systems have been around for at least 10 Billion years longer than our, relatively new, system. And we know that a rational advanced species would not sit on it’s rock and wait to die as it’s sun exploded. The only logical conclusion is that the galaxy will be filled with various space faring life, some of it quite ancient.

It will also be the case that The Wanderers will need to wander out toward the ‘newer’ regions toward the spiral arms. Why? Because the black hole in the center of the galaxy will eventually suck in and doom anything staying too close for too long. Because it is older near the center and, thus, will be more fully explored, owned, and unavailable. Because there will be more opportunity for new places, new materials, new adventures, and, frankly, being left the hell alone; out in the boonies. There is also the geometric imperative that expansion outward gives more opportunities for growth while expansion inward will reach a fill and stop point.

Even if expansion inward happened, after 10 Billion years, it would be full, and things would turn outward.

So while it’s likely that there is life, and lots of it, toward the galactic center (though in the very central regions the place is so crowded and chaotic with stars in crazy complex orbits and lots of interactions that life would be a bit hard…) there ought to be a very complex set of old societies of many different life forms interacting. Unless, of course, one of them is a Borg like “destroyer of worlds”… It is toward the outer edges that a rational society would head. It gives the maximum life span to that society and the most opportunity to develop as they wish, away from the chaos of the core groups.

All of which implies that there simply will be generational ships, some quite large, floating around ‘out here’. Most likely arriving from the direction of the older and more crowded central regions. Most likely NOT interested in advertising their existence too broadly (lest some malevolent society ‘mess with them’). And while they might hang around for a few generations, the general cultural norm will be to ‘move along’. They have already made the leap to space to avoid Star Death, so why would they want to go back to being rock bound?

And that, IMHO, is the simplest answer that accounts for all the facts. Even the new ones about just how crammed full of planets our galaxy happens to be.

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