As far as astrobiology goes, planets are it. They're the show. And yes, even though these billions of rocky planets in our own Milky Way are in our own backyard, relative to the known universe, the distances between any one of them and us, given the speed limit in physics as we know it (When has Einstein been wrong? Not often.), messages sent between electromagnetically intelligent beings "out there" would take probably 1000 years to send-receive questions/answers/how's it going?-like stuff (that's one helluva delay, eh?), I don't think that's any reason to lose hope of making some sort of contact. I find the distances plus speed of light sobering, though. The 1000 years is probably being overly optimistic, too. It's probably around 100,000 light years across the galaxy from "end to end." But still: billions of other worlds in our galaxy, possibly some with life? Marvelous to think on, no? Some with technologically intelligent life? Who haven't yet made themselves extinct by the time they sent us a message? Beyond marvelous!
search for exoplanets was aptly named after him.
And then maybe rocky planets in habitable zones with water with atmospheres, with...the luck we've had? It could be the details make us very rare. But still: the sheer numbers of possible worlds that could harbor life, and maybe technologically intelligent life...it's a new new thing! It's a scientific revolution. We've seen it happen over just the last 14 years or so. Things have changed at breathtaking speed when it comes to the exoplanet question, and those changes have been accelerating.
In yesterday's post I showed a graph of the exoplanets discovered by year and mass. The graph went up to 19 January, 2012. I hope to convey something of the rapidity of change in this area of science, right now:
Science Daily, 2 February, 2012: a new Super-Earth discovered orbiting a star in a triple-star system. They think it's potentially habitable. The planet, called GJ667Cc (they need to work on this naming thing, right?), has a 28 day orbital period and it's about five times the mass of Earth, and it's "only" 22 light years away. (Light travels at about 186,000 miles per second. That makes for about 6,000,000,000,000 miles a year. That's 6 trillion miles. Times 22 equals 132 trillion miles away. And that's considered fairly "close" to us, considering....) The star this new Super Earth orbits lacks metals our sun has, so it suggests that habitable planets could make up a greater variety of elements than we'd thought. One of the lead discoverers of this new exoplanet says, "This planet is the new best candidate to support liquid water, and perhaps, life as we know it." Yes, maybe.
system for galaxies, based on their shapes. He has a
doozy of a telescope named after him.
BBC, 21 February, 2012: "Distant Water-World Confirmed." Another group has found a planet 40 light years away. It's a Super-Earth, about two and a half times the diameter of Earth but seven times the mass. The Hubble Space Telescope was used. A large fraction of this new world is water! But what kind of water? It's "like no planet we know of," says one researcher. It's about 392 degrees Fahrenheit on the surface, so the mass and pressure and temperature might mean it has a different internal structure than our Earth, and might contain exotic matter like "hot ice" (which I think means sodium acetate?), and something called "superfluid water."Weird stuff. This planet, which I call "Superfluid World," the astronomers call, at present, GJ1214b. It orbits a red dwarf, which for some reason, every time I see that term I think of a David Lynch film. But that's me...
San Francisco Chronicle, 24 February, 2012: Rogue planets may outnumber stars in the Milky Way. Note that the writer and editor of this piece fall prey to what most of us do when we're talking about this stuff, because the numbers and scales are so large and mind-blowing in their implications: early in the article there may be perhaps "thousands" of rogue planets. But the crux is that, for every main-sequence star in the Milky Way - around 200 billion - there may be 100,000 rogue/nomad planets for each star! I don't know what the current scientific consensus is on this idea, but in an intellectual domain already fraught with seemingly absurd data, this seemed to really take the cake for me. These nomadic planets are thought to be Jupiter-like, and according to the team of scientists here, they may be powered by internal radioactivity, possess thick atmospheres, and harbor microbial life. So, this team of researchers, centered at Stanford, posit 200,000,000,000 x 100,000 = the number of homeless, wandering planets in the Milky Way!
How do they figure? They know the mass of the galaxy. They added the mass of all known comets, planets (that are confirmed: by this moment it was 500 confirmed exoplanets and about 1800 pending), and stars in the galaxy. They got a number that was far too low. It didn't come close to the known mass of the galaxy. Hence, rogue Jupiter-like planets. Scads and heaps and hordes of them! Swarms and masses and crowds of them!
Now: I'm merely a generalist, if an overweening one. But could it be possible that these guys and gals with PhDs in astrophysics are hinting at a solution to the Dark Matter problem? It's often been called the "most embarrassing" problem in science: our ignorance of two things that sound alike, but are probably very different: Dark Matter and Dark Energy. Dark Energy makes up about 73% of Everything, and we don't have a decent theory of what The Stuff Is. Dark Energy is about 23% of Everything, and we are having a rough time accounting for it also. That's 96% of Everything we're ignorant about. Here's a little chart that lays out the glaring embarrassment:
28 March, 2012, Wired: Ten Billion Earth-Like Planets May Exist In Our Galaxy. Now it's Earth-Like planets! 10 billion of them. 40% of red dwarf stars may contain Earth-ish planets with the right conditions for life. Red dwarfs aren't as hot, so these things, even if Super-Earths, could orbit at 0.5 of an AU and still be "just right." With water, etc. This article gives "700 confirmed" exoplanets. It seems like only 36 days ago the confirmation number was 500, and indeed it was. We're talking acceleration of knowledge, folks.
New Scientist/Slate, 8 April, 2012: Interview with the founder of 70 of the first 100 exoplanets, Dr. Geoffrey Marcy, given ample space in my previous blogspew. Read the interview. He's the Pioneer of Exoplanet Hunters; now he's got some great ideas for SETI and explains how using lasers is the way we'll contact The Others.
Marcy says we can break planets into three main classes:
- Jupiter-like thingies, consisting of mostly hydrogen and helium. Big, gassy blobs.
- Water-dominated planets that are pretty big, but not as big as Jupiter: Icy Neptune-y and Uranus-ish guys.
- Rocky Ones, like us and our immediate cousins (who, admittedly, have their problems): Venus and Mars.
May 1st, 2012, Phys.org: Four white dwarfs have been caught eating their Earth-like planets. What?
Okay, a white dwarf is at the end of its life as a star. Our star is about halfway through its life-cycle. It still has about another five billion years before it goes Red Giant, totally burns to a crisp Mercury and Venus, and scorches with extreme prejudice the face of Earth. That's what they found orbiting those old white dwarfs: discs of dust containing the tell-tale nickel, sulfur, and iron...stuff that's at the core of our planet. So: for rocky planets at or less than one AU from their own Type G star, they're gonna be toast. After the star goes Red Giant, it contracts, turns into a cooler white dwarf, and loses mass. The bigger outer planets probably lose their moorings; they old star can't keep them tethered any longer, and they...go rogue. They wander. Probably many of them bump into each other, shattering in unspeakably large cataclysmic events into more dust, asteroids, comets...Dark Matter?
"My theology, briefly, if that the universe was dictated but not signed." - Christopher Morley
"At the last dim horizon, we search among the ghostly errors of observations for landmarks that are scarcely more substantial. The urge is older than history. It is not satisfied and will not be oppressed."