Weather on Titan: New Season, New Knowledge

"On Saturn's Moon Titan, Methane Rains on the Desert"
Denise Chow, Space.com (March 17, 2011)

"When photos showed a large patch near the equator of Titan mysteriously darken and then grow lighter within a couple of weeks, scientists knew something big was happening on Saturn's largest moon. But what they found was something they didn't expect: a methane rainstorm in a region of Titan thought to be covered by vast, arid dunes.

"While the large moon is known to have methane lakes at its north and south poles, scientists thought Titan's equatorial region was mostly dry, but the likely cause of the darkness was determined to be an outburst of clouds and methane rain - which suggests Titan's equator has a rainy season.

"The photos taken by NASA's Cassini spacecraft on Sept. 27, 2010, showed a decrease in brightness over an area measuring over 1,200 miles (2,000 kilometers) long and 62 miles (100 km) wide...."

A key word in the article, in the Lemming's opinion, is "suggests." Rain on that part of Titan isn't guesswork, though:

"...Turtle and her colleagues examined other explanations for the darkening seen in Cassini's images, including strong windstorms and volcanism. Through their analyses, however, the researchers found that the effects of possible windstorms and volcanism on Titan were not consistent with the changes observed over such a large area...."

At this point, it looks like Titan's weather systems are like Earth's - but not quite. There's a diagram that shows what seems to be a reasonable model for how Titan's weather works:


(P. Huey/Science © 2011 AAAS, via Space.com, used w/o permission)
"Cloudy with rain. Simplified global atmospheric circulation and precipitation pattern on Titan and Earth. Most precipitation occurs at the intertropical convergence zone, or ITCZ, where air ascends as a result of convergence of surface winds from the northern and southern directions. Titan's ITCZ was previously near the south pole (A) but is currently on its way to the north pole (B). The seasonal migration of the ITCZ on Earth is much smaller (C and D). This image appears in a Perspective by Tetsuya Tokano titled, 'Precipitation Climatology on Titan.'
"CREDIT: P. Huey/Science © 2011 AAAS"

Saturn, and Saturn's moon Titan, go around our sun once for every 29 trips Earth makes - which means that it's going to be a while before we get a full year's worth of seasonal data. The Space.com article notes that Cassini got the Saturn system in 2004 - so data from that probe covers about a quarter of the Saturn/Titan year.

Still, it's more than we knew before.

Related posts:

• " 'Arsenic and Old Lakes' - What a Catchy Title!"
  (January 26, 2011)
• "NASA, Extraterrestrial Life: and Titan is a Moon of Saturn, not Mars"
  (December 1, 2010)
• "Ah,to be On Titan in the Spring"
  (September 25, 2010)
• "Life on Titan! Or, Not"
  (June 7, 2010)
• "Titan, Life Without Water, and 'Messing With Old Definitions' "
  (March 24, 2010)

Saturn's Rings: New Explanation for a Spectacular Sight

"Saturn's Rings May Be Remains of Ripped-Apart Moon"
Mike Wall, Space.com (December 12, 2010)

"Saturn's famous rings are the last remaining shards of a huge moon the planet tore apart long ago, a new study suggests.

"A moon about the size of Titan — Saturn's largest satellite — likely spiraled into the giant planet about 4.5 billion years ago, scientists think. As it made its way, Saturn's powerful gravity stripped off the doomed moon's icy outer layers, thus spawning the planet's magnificent rings, according to the research. [Gallery: The Rings and Moons of Saturn]

"And, in death, this lost moon may have given other satellites life, the study suggests. Over the eons, much of the ring material has glommed together, forming the icy inner moons of Saturn.

" 'This model implies that the rings are primordial, that they formed from the same processes that left Titan as Saturn's only large satellite,' said study author Robin Canup of the Southwest Research Institute in Boulder, Colo. "'And it's the only self-consistent explanation for the ice-rich inner satellites.'..."

Part of the puzzle of Saturn's rings is that they're mostly water ice. Which is odd - since mathematical models which do a good job of explaining how the outer planets formed, and observations, show that material available was ice and rock.

The new model involves a moon like Titan, with a rocky core and water ice near the surface, in a decaying orbit around Saturn. The rocky core eventually fell in, but on the way tidal forces stripped water ice off - part of which formed the rings. Some of the rest, again according to this new model, clumped together to form Saturn's inner satellites.

The new model passes the Occam's Razor test:

"..."The other theories have the rings forming from a sort of random event," Canup said. 'This model reduces the number of things that have to happen, which I think makes it more probable.'..."

"Occam's Razor?" Essentially, it's that a simpler solution is more likely to be true. ("THEY are After McCain: Conspiracy Theories, Anyone?," Another War-on-Terror Blog (April 4, 2008))

NASA, Extraterrestrial Life: and Titan is a Moon of Saturn, not Mars

---

Update (December 2, 2010)
More on the NASA announcement:

• "Arsenic and Old Science: NASA and Extraterrestrial Life"
  (December 2, 2010)

---

Another reason why the Lemming takes what's in the news with a few truckloads of salt:

"Rumor Roundup: Has NASA Discovered Alien Life?"
Air & Space, FOXNews (December 1, 2010)

"A NASA press release announcing "an astrobiology finding" -- something that will impact the search for extraterrestrial life -- has sent shockwaves through the blogosphere.

The press release simply announces an event, set for Thursday at 2 p.m. EST, to discuss an astrobiology discovery 'that will impact the search for evidence of extraterrestrial life.' Astrobiology is the study of the origin, evolution, distribution and future of life in the universe.

And the concept of NASA discussing alien life has everyone a-Twitter. Gawker, PC World, New Scientist and others have all speculated about the news -- even suggesting that the space agency may reveal that E.T. has finally arrived.

The reality may be less dramatic, though still intriguing: Based on the background of the four conference participants NASA cites, the announcement will probably concern lifeforms that live off of poisonous arsenic. Popular blogger Jason Kottke and others have concluded that the announcement will tie into the quest for life on the Martian moon Titan.

'I'd say that they've discovered arsenic on Titan and maybe even detected chemical evidence of bacteria utilizing it for photosynthesis,' Kottke theorizes, a hypothesis short of actually confirming alien life...."

Again, a link to the Kottke post:

• "Has NASA discovered extraterrestrial life?"
  Kottke.org (November 29, 2010)

Mr. Kottke, by the way, identifies Titan - correctly - as a moon of SATURN, not Mars.

Yes: Mars has moons. Two of them. Really tiny moons. They're called Phobos and Demos.

Mars is not Saturn. Saturn is an entirely different planet. Titan orbits Saturn.

The NASA media advisory ("NASA Sets News Conference on Astrobiology Discovery; Science Journal Has Embargoed Details Until 2 p.m. EST On Dec. 2" (November 29, 2010)) doesn't mention Titan, Saturn, or Mars, by the way.

FOXNews sometimes identifies an article's writer: not this time. Just as well, maybe. This isn't the sort of gaffe a reporter - or editor - would want 'on the record.'

It's a little like a sports writer referring to the Super Bowl as a basketball game, or someone covering international news writing, "in Hong Kong, the capital of Germany...."

The Lemming speculates that the 'Titan is a moon of Saturn' reporter may have been lead astray by the Gawker article.


(NASA, cited by Gawker, used w/o permission)
Red, yes; Mars, no.

Gawker displays an artist's impression of a lake on Titan: and identifies it as such, at the end of their article. So I suppose a reporter could have seen the picture, noticed that it was red, associated red -> red planet -> The Angry Red Planet -> Mars: and did not noticed the "Did NASA Discover Life on One of Saturn's Moons?" headline right above the picture.

Still - "the Martian moon Titan"?!!

Related posts:

• "Viking Life Experiments, Revisited"
  (September 14, 2010)
• "Organic Compounds in Murchison Meteor: Lots of Them"
  (February 16, 2010)
• "Another Hot Jupiter With Organic Compounds"
  (October 21, 2009)
• "DNA - A Universal Pattern? Could Be"
  (April 8, 2009)
• "Life on Ceres? Could Be"
  (March 5, 2009)
  Particularly
  • Exploding Martians and the Viking Life Experiment

More related posts, at

• "Mars, Mostly"
• "A Serious Search for Other Worlds, Life, and - Maybe - Extra-Terrestrial Intelligence"

Ah, to be On Titan in the Spring

"Springtime for Northern Titan: Seven Years of Clearer Skies"
Space.com (September 24, 2010)

"The clouds are clearing on Titan as spring takes hold in its northern hemisphere, signaling a shift in the weather patterns on Saturn's largest moon, a new study finds.

"Titan is poised for a mostly sunny spring, one that will last seven Earth years, researchers have found. Seasons on Titan last so long because it takes the moon and Saturn about 30 years to orbit the sun. [New photo of Titan clouds.]

"Scientists analyzed data from the last six years of observations by NASA's Cassini spacecraft to piece together how Titan's weather cycle works. They found that conditions have changed since August 2009 - when the sun was directly over Titan's equator during its latest equinox..."

As the Lemming has written before, sometimes data shows that the mathematical models scientists developed to account for an earlier set of data don't fit what's really happening. Other times, they do. Either way, something's learned.

In this case, so far, it looks like the models are on the same page as the reality.

"...These findings match predictions by computer models developed by other researchers in the past. Rodriguez and his team combined those models with the actual Titan observations to understand Titan's evolving cloud patterns.

"Different cloud-formation mechanisms are likely at work in the different hemispheres, the researchers said...."

It a way, Titan is more like Earth than is Mars. Both worlds have a relatively thick atmosphere with lots of nitrogen, lakes, rivers, clouds and rain.

There are differences, of course:

"...Titan and its weather have intrigued scientists for decades. Some think Earth resembled Titan before life took hold — only not nearly as cold. Titan's surface averages 290 degrees below zero Fahrenheit (minus 179 degrees Celsius).

"Titan has a thick, nitrogen-rich atmosphere, and its surface features have been carved by the action of liquid hydrocarbons like methane, which is the chief component of natural gas here on Earth. Methane rain drizzles from Titan's clouds, pooling in frigid liquid lakes...."

Which brings up another point: Earth might have been more like Titan, only warmer, before runaway photosynthesis polluted this planet's atmosphere with that dangerously reactive gas, oxygen.

Sure: (Most) animals use oxygen these days - and (most) other organisms can endure it. But we're pretty sure it wasn't always that way. (April 9, 2010)

Change happens. And the Lemming is repeating himself again.

Related posts:

• "Life on Titan! Or, Not"
  (June 7, 2010)
• "Animals That Don't Need Oxygen - It Gets Weirder"
  (April 9, 2010)
• "Titan, Life Without Water, and 'Messing With Old Definitions' "
  (March 24, 2010)

Life on Titan! Or, Not

"Strange Discovery on Titan Leads to Speculation of Alien Life "
Space.com (June 7, 2010)

"New findings have roused a great deal of hoopla over the possibility of life on Saturn's moon Titan, which some news reports have further hyped up as hints of extraterrestrials.

"However, scientists also caution that aliens might have nothing to do with these findings.

"All this excitement is rooted in analyses of chemical data returned by NASA's Cassini spacecraft. One study suggested that hydrogen was flowing down through Titan's atmosphere and disappearing at the surface. Astrobiologist Chris McKay at NASA Ames Research Center speculated this could be a tantalizing hint that hydrogen is getting consumed by life.

" 'It's the obvious gas for life to consume on Titan, similar to the way we consume oxygen on Earth,' McKay said.

"Another study investigating hydrocarbons on Titan's surface found a lack of acetylene, a compound that could be consumed as food by life that relies on liquid methane instead of liquid water to live...."

Or, there could be chemistry and/or physics happening on Titan that isn't biological, isn't living.

We just don't know. Yet.

One thing the scientists expected to find was acetylene on the surface. They didn't. That could mean that there are acetylene-eating critters on Titan - or radiation is converting acetylene in the atmosphere into compounds that don't show up on instruments (or haven't been linked to the acetylene dearth) - or something else is going on.

Whatever is going on: there's a lot more to learn about that moon of Saturn's.

Related posts, not all in this blog:

• "Alien Life will Most Likely be - Alien"
  Drifting at the Edge of Time and Space (April 12, 2010)
• "Titan, Life Without Water, and 'Messing With Old Definitions'"
  (March 24, 2010)
• "Beautiful Space Princesses, Almost Certainly Not: Flying Whales, Maybe"
  Drifting at the Edge ot Time and Space (December 8, 2009)
• "Life on Ceres? Could Be"
  (March 5, 2009)
  Particularly
  Exploding Martians and the Viking Life Experiment

---

Related posts, at

• "A Serious Search for Other Worlds, Life, and - Maybe - Extra-Terrestrial Intelligence"

Early Earth Didn't Freeze: Why?!

"How Early Earth Got Warm and Hospitable"
Space.com (June 3, 2010)

"Our planet might have kept warm in the super-ancient past when the sun was substantially dimmer than it is today because of a complex brew of global warming gases much like that now enveloping Saturn's moon Titan, scientists reveal.

"These new findings could also shed light on how the building blocks of life might have formed on Earth.

"When the sun was young, models suggest it was just 70 percent as bright as it is now. However, during the first two billion years or so of Earth's history, the surface of the planet was warm enough for glaciers to not form and early life to emerge...."

The article gives a pretty good overview of what's been discussed over the last several decades, about what Earth was like a really long time ago. Including the continuing story of ammonia in Earth's atmosphere. If you take ammonia and methane, and add electrical sparks: you get amino acids and other organic building blocks. Not life - but the parts you'd need for living organisms.

Just one problem - ultraviolet light destroys ammonia, and there would have been a whole lot of ultraviolet light back then.

Or, not. Something called fractal size distribution in the gasses we're pretty sure were in Earth's atmosphere should have blocked the shorter ultraviolet wavelengths, preserving ammonia, and let in longer visible light: keeping our planet warm.

Fascinating! If you're interested in that sort of thing.

If there's a lesson to be learned here: Change happens.

---

Related posts, at

• "Change, American Culture, Trilobites, Humanity's History, and the Big Picture"
• "A Serious Search for Other Worlds, Life, and - Maybe - Extra-Terrestrial Intelligence"

Titan, Life Without Water, and "Messing With Old Definitions"

"Can Life on Titan Thrive Without Water?"
Space.com (March 23, 2010)

"New discoveries have a way of messing with old definitions. Take, for example, the concept of a habitable world.

"The standard definition of a 'habitable world' is a world with liquid water at its surface; the "habitable zone" around a star is defined as that Goldilocks region — not too hot, not too cold — where a watery planet or moon can exist.

"And then there's Titan. Saturn's giant moon Titan lies about as far from the standard definition of habitable as one can get. The temperature at its surface hovers around 94 degrees Kelvin (minus 179 C, or minus 290 F). At that temperature, water is a rock as hard as granite.

"And yet many scientists now believe life may have found a way to take hold on Titan. Water may all be frozen solid, but methane and ethane are liquids. In the past few years, instruments on NASA's Cassini spacecraft and images captured by ESA's Huygens probe have revealed an astonishing world with a complete liquid cycle, much like the hydrologic cycle on Earth, but based on methane and ethane rather than on water...."

Actually, the idea that life didn't necessarily need water isn't particularly new. A former professor (of chemistry, apparently) at Boston University put together a pretty good argument for a half-dozen life chemistries that might plausibly work in temperatures ranging from near red-hot to near absolute zero:

1. Fluorosilicone in fluorosilicone
2. Fluorocarbon in sulfur
3. Nucleic acid/protein (O) in water
4. Nucleic acid/protein (N) in ammonia
5. Lipid in methane
6. Lipid in hydrogen
   "View from a Height" Isaac Asimov (1963), Lancer Books (p. 63)

Isaac Asimov might be shaky on the sciences of ecology and physics - at least in his fiction - but that was in his professional field: chemistry. I'm inclined to take his view seriously, that life-as-we-know-it isn't necessarily the only sort. We're #3 on that list, by the way.

Back to the article:

"...The chance to discover a form of life with a different chemical basis than life on Earth has led some researchers to consider Titan the most important world on which to search for extraterrestrial life. In a recent paper in the journal Astrobiology, Robert Shapiro, a professor of chemistry at New York University, and Dirk Shulze-Makuch of Washington State University rated Titan a higher-priority target for investigation than even Mars...."

Not everybody agrees, of course.

I can see the other point of view. The only sort of life we know exists involves nucleic acids and proteins. Nucleic acids and proteins on earth have more oxygen atoms than nitrogen atoms - indicated by (O) in Dr.¹ Asimov's list. He pointed out that (as of the early sixties) it wasn't unreasonable to suppose that nucleic acids and proteins with more nitrogen atoms than oxygen - indicated by (N) - couldn't exist. We don't find them on Earth, but considering how boiling hot it is here, that shouldn't be a surprise. (Ammonia is a gas in our home world's temperature range.)

I'm inclined to take Shapiro and Dirk Shulze-Makuch - and Asimov - seriously. At least, I see their points of view as being a trifle more reasonable than a more familiar 'I never thought of such a thing: therefore it doesn't exist' attitude. (More: Exploding Martians and the Viking Life Experiment (March 5, 2009))

Related posts:

• "Earth May Not Be a 'Class M' Planet"
  (December 5, 2009)
• "Life on Ceres? Could Be"
  (March 5, 2009)
  Particularly
  Exploding Martians and the Viking Life Experiment

---

Related posts, at

• "A Serious Search for Other Worlds, Life, and - Maybe - Extra-Terrestrial Intelligence"

---

¹ Doctorate in chemistry, 1948. ("Isaac Asimov" Columbia 250)

Robot Buoy to Titan - Maybe

"Nuclear-Powered Robot Ship Could Sail Seas of Titan"
Space.com (October 14, 2009)

"One of NASA's next great adventures could take place with a raindrop-flecked camera bobbing around on extraterrestrial waves. Or at least, that's the hope of several researchers who want to sail an unmanned, nuclear-powered capsule on Saturn's moon Titan.

"Titan eerily resembles Earth with characteristics such as wind, rain and lakes, but all within the bounds of a frigid environment where methane and ethane replace liquid water. The many lakes dotting the moon's surface suggested an alternative mission proposal compared to the usual rovers and hard surface landers that NASA has sent to other destinations.

" 'We got funded to look at the possibility of sending a lake lander to Titan,' said Ellen Stofan, a geologist with Proxemy Research in Maryland. 'Scientifically, it's sort of a beyond obvious thing to do.'..."

On radar maps, quite a lot of Titan's northern hemisphere, above around 60° latitude looks like the lake country, north of my home here in Minnesota. The 'water' there is most likely hydrocarbons and the temperature averages around -292 degrees Fahrenheit or -180 Celsius: substantially colder than a Minnesota winter.

Still, the article says that two of Titan's lakes are about the size of North America's Great Lakes or Eurasia's Black Sea: big enough to be quite certain of landing a probe in the lake, and not on the surrounding land.

Sure, the lake's 'water' is ethane and/or methane; and really cold: but it's liquid. Which is much easier to land - safely - in than solid ground. That's why America landed its pre-shuttle spacecraft in water - and the former Soviet Union and now Russia probably would have, except that Russia is frustratingly short on usable seaports.

The roboship - if it gets funded - would probably be powered by an ASRG - Advanced Stirling Radioisotope Generator.

Horrors! Was That "Radioisotope"?!!

Yeah: a (shudder) nuclear reactor.

Sort of. The things use heat from nuclear decay - not actual fission. The heat runs a piston which in turn runs an electrical generator. Compact, fairly efficient, and the new generators use about a quarter of the plutonium needed by earlier models.

Why the (shudder)? Well, as anybody who's seen "Godzilla" and "The Swarm" knows, nuclear anything is pretty much awful and dangerous and shouldn't ever be used because something dreadful will happen. (The Lemming is lazy today: I used the same two movies in this blog's last post.)

If the Titan lake lander gets launched, I'm pretty sure there will be the usual protesters with signs. I'm concerned about the (remote) possibility of plutonium getting dropped, if something goes wrong during launch. But I also recognize that life is inherently risky: and that the benefit/risk ratio in this case seems very favorable.

But then, I'm rather of the 'follow knowledge like a sinking star, beyond the utmost bounds of human thought' sort. I like knowledge.

And dangerous pollution is nothing new.

Smog Blows Away - - -

Before internal combustion engines replaced horses as a power source for vehicles, cities like London had pollution problems that'd give your standard-issue environmentalist activist fits. For good reason: I've shoveled enough of the stuff, myself - and it's no picnic to handle, even for someone without much of a sense of smell.

Great Science; Doable Technology; Funding Could be a Problem

The lake lander mission may never get off the ground. NASA has a finite budget and may not give the go-ahead for the project.

Which will be a bit of a disappointment, but hardly the end of the road for landing a buoy in Titan's lakes.

It'll take a while for private-sector efforts to get the vehicle inventory and investors for a project like that, but my guess that even if NASA abandoned Saturn-system exploration entirely, my children - or their children - would see the launch of a non-government robotic expedition to Titan. (October 4, 2009)

Think Jacques Cousteau and the Calypso in space.

Cool Maps

(NASA/JPL, via Space.com, used w/o permission)


(NASA/JPL, used w/o permission)
"Titan's North Polar Region"
(October 11, 2007)
"This Cassini false-color mosaic shows all synthetic-aperture radar images to date of Titan's north polar region. Approximately 60 percent of Titan's north polar region, above 60 degrees north latitude, is now mapped with radar. About 14 percent of the mapped region is covered by what is interpreted as liquid hydrocarbon lakes.

"Features appearing darkest to the radar, which are thought to be liquid, are shown in blue and black, and the radar-bright areas likely to be solid surface are tinted brown. The terrain in the top center of this mosaic is imaged at lower resolution than the remainder of the image...."
(NASA/JPL)

Vaguely related posts:

• "When it's Time to Build Spaceships, People Will Build Spaceships"
  (October 4, 2009)
• "Two Decades Later: Voyager 1 Flyby of Triton, August 21, 1989"
  (August 21, 2009)
• "Atomic Science Set"
  (March 30, 2009)
• "Futurists Through the Centuries"
  (November 1, 2007)

Two Decades Later: Voyager 1 Flyby of Triton, August 21, 1989

"Aug. 21, 1989: Voyager 2 Reaches Triton"
This Day in Tech, Wired (August 21, 2009)

"1989: Twelve years and one day after liftoff, Voyager 2 reaches Triton, the largest of Neptune's eight moons and the coldest, most unusual satellite in our solar system.

"Launched from Cape Canaveral on Aug. 20, 1977, Voyager 2, as the name suggests, was the second of two identical deep-space probes originally dispatched by NASA to gather data on Jupiter and Saturn. Their primary mission completed, Voyager 2 continued on to make observations of Uranus and Neptune, while Voyager 1 hightailed it toward the edge of the solar system. Voyager 2’s flyby of Triton was the spacecraft's last contact with a major heavenly body before heading off in the direction of Voyager 1 and interstellar space...."

That was 20 years ago, today. This short Wired article gives a brief overview of the Voyager 1 flyby of Triton and the two Voyager missions. A day over 32 years after Voyager 1's launch, both spacecraft are still active, coasting through the outer parts of our sun's heliopause, and expected to keep sending data until 2025.

NASA has a bit more information about Triton: "Neptune: Moons: Triton;" a more complete description of that color image displayed by Wired; and a 26-image gallery, including a few artistic composites and quite a number of images.

Including this color image, which seems to be the original of Wired's version:

"PIA00317: Global Color Mosaic of Triton "


"Global color mosaic of Triton, taken in 1989 by Voyager 2 during its flyby of the Neptune system. Color was synthesized by combining high-resolution images taken through orange, violet, and ultraviolet filters; these images were displayed as red, green, and blue images and combined to create this color version. With a radius of 1,350 (839 mi), about 22% smaller than Earth's moon, Triton is by far the largest satellite of Neptune. It is one of only three objects in the Solar System known to have a nitrogen-dominated atmosphere (the others are Earth and Saturn's giant moon, Titan)...."

A Serious Search for Other Worlds, Life, and - Maybe - Extra-Terrestrial Intelligence

Searching the stars for "new life and new civilizations" is the stuff of science fiction. And, to an increasing extent, the job of professional scientists.

We're living at a point in history where humanity is rapidly discovering new worlds: some so strange that scientists are having to change old assumptions, and develop new models to explain what their instruments detect.

I would be very surprised if my children's children see something like Star Trek's warp drive. On the other hand, Alcubierre's intriguing equations suggest that we'll be able to travel faster than the speed of light: as soon as we figure out how to build machines that can warp space-time on a fairly large scale.

While physicists are exploring the horizon of their field, speculating on how a practical interstellar spaceship could be designed, and biologists are learning more about how life works, astronomers and others are putting together an increasingly extensive list of places to check out:

• "Planets: Rocky, Smaller than Earth, Three of Them"
  (January 23, 2012)
• "The 'Christmas Planet:' Kepler-22b"
  (December 12, 2011)
• "Exoplanets: Over 700 Found to Date; Latest Batch of 18 are Jupiter-Size"
  (December 5, 2011)
• "Mexico's Crystal Cave and Astrobiologist Boston"
  (June 3, 2011)
• "Gliese 581d: Rocky, Close (sort of), and Liquid Water (could be, maybe)"
  (May 18, 2011)
• "55 Cancri e - A Fairly Dense, Fairly Big, Very Intriguing, Exoplanet"
  (May 2, 2011)
• "Apex Chert: Microfossils, Microfractures, or Maybe Both"
  (April 23, 2011)
• "Kepler 11: A Tightly-Packed Planetary System"
  (February 2, 2011)
• "'Arsenic and Old Lakes' - What a Catchy Title!"
  (January 26, 2011)
• "Kepler-10b: Hot, Rocky, and the Smallest Exoplanet Yet"
  (January 11, 2011)
• "Beware Warmonger Imperialist Space Aliens!?"
  (January 11, 2011)
• "Viking Life Experiments: Another Look at Organic Stuff on Mars"
  (January 6, 2011)
• "Shifty Surface on Mars?"
  (January 5, 2011)
• "GJ 1214b: Super-Earth, With an Interesting Atmosphere"
  (December 2, 2010)
• "Arsenic and Old Science: NASA and Extraterrestrial Life"
  (December 2, 2010)
• "NASA, Extraterrestrial Life: and Titan is a Moon of Saturn, not Mars"
  (December 1, 2010)
• "Life on Mars Might be Life From Earth"
  (November 2, 2010)
• "Two Planets, Each Orbiting the Same Two Stars"
  (October 26, 2010)
• "Gliese 581g: Then Again, Maybe So"
  (October 14, 2010)
  • Or, looking at all the data
• "Gliese 581g? Maybe Not"
  (October 13, 2010)
• "Gliese 581g, Space Aliens, and the Canals of Mars"
  (October 12, 2010)
• "Gliese 581g, Alien Angst, and the Lemming"
  (October 4, 2010)
• "Gliese 581g: Life? Maybe"
  (October 2, 2010)
• "Gliese 581 Planetary System: Possible Habitable Planet"
  (October 1, 2010)
• "Nuclear Weapons, Space Aliens, Conspiracy Theories, and Getting a Grip"
  (September 24, 2010)
• "Looks Like a Cosmic Constant - Isn't"
  (September 16, 2010)
  
• "Mars, Mud Volcanoes, and the Search for Life"
  (August 20, 2010)
• "Sinister Bias in Life's Chemicals Linked to Supernovas"
  (August 17, 2010)
• "Report of a UFO Would 'Destroy One's Belief in the Church?!' "
  A Catholic Citizen in America (August 6, 2010)
• " 'More Than 100 Earth-Like Planets' Found? Well, No: Not Really"
  (July 24, 2010)
• "Planets Gone Wild, Life as We Know It, and Orbital Mechanics"
  (July 10, 2010)
• "Life Around a Red Dwarf Star? Could be"
  (July 7, 2010)
• "Another Martian Cave: Discovered by Seventh Graders"
  (June 22, 2010)
• "Earth and Moon May Be Younger Than Thought - But Not By Much"
  (June 12, 2010)
• "Life on Titan! Or, Not "
  (June 7, 2010)
• "Early Earth Didn't Freeze: Why?!"
  (June 6, 2010)
• "Thar's Oxygen in That There Moon! - Maybe"
  (May 29, 2010)
• "Upsilon Andromedae, Tilted Orbits, and Habitable Worlds"
  (May 25, 2010)
• "Mars isn't Earth, Earth isn't Mars: And Why That Matters"
  (May 12, 2010)
• "More Earth-Like Worlds Than We Thought? Another Look"
  (April 13, 2010)
• "A Star and a Planet; or Two Planets; or a Brown Dwarf and a Planet; or Something Else"
  (April 10, 2010)
• "Titan, Life Without Water, and 'Messing With Old Definitions' "
  (March 24, 2010)
• "Another Hot Jupiter: Much Farther From Its Star Than Others"
  (March 19, 2010)
• "Planets Found Circling Other Stars: 429 So Far"
  (February 15, 2010)
• "Alien Dust, HD 131488, and the Puzzle of Planets"
  (January 15, 2010)
• "Second Smallest Exoplanet Found: HD 156668b (Caution! Geeky Content!)"
  (January 10, 2010)
• "Early Returns From Galactic Census: Not As Many Planets as Expected"
  (January 9, 2010)
• "Earth Exists: New Planetary Formation Model Explains Why"
  (January 8, 2010)
• "Outer Solar System: More Planets? And What to Do With Them"
  (January 5, 2010)
• "Mars Rover Breakdown Leads to New Data"
  (December 23, 2009)
• "Probable Super-Earths Found: One Nearby"
  (December 14, 2009)
• "Spectacular UFO and the Norwegian Space Centre"
  (December 11, 2009)
• "How to Handle Mars Rocks"
  (December 5, 2009)
• "Earth May Not Be a 'Class M' Planet"
  (December 5, 2009)
• "Kids, Try This at Home: Man's Search for Aliens Got Him Fired"
  (December 2, 2009)
• "Water - On the Moon?!"
  (November 15, 2009)
• "Low on Lithium? If the Star's the Size of the Sun: It's Probably Got Planets"
  (November 11, 2009)
• "Very Young Planetary System: HR 8799"
  (November 11, 2009)
• "Space Aliens, the News, and Those Catholics"
  (November 11, 2009)
• "Space Aliens, Stars, Scientists, and This is Where I Came In"
  (November 5, 2009)
• "NASA Studying Recipe for a Planet"
  (October 29, 2009)
• "The Caves of Mars"
  (October 26, 2009)
• "Another Hot Jupiter With Organic Compounds"
  (October 21, 2009)
• "Water, Water Everywhere - Even on the Moon - Again"
  (September 28, 2009)
• "Left-Handed Life: Why are We So Sinister?"
  (September 17, 2009)
• "Bee Communication and Non-Human Intelligence; And a Dying Planet"
  (August 28, 2009)
• "Death Rays From Space - No, Really"
  (August 28, 2009)
• "Bugs in Space, Day 2: or, Stop Earthlings Now!"
  (August 26, 2009)
• "Planets, Stars: What's the Difference? Good Question"
  (August 17, 2009)
• "Life on Other Worlds: Evolution, Orbits, and the Galactic Environment"
  (August 13, 2009)
• "Planets Collided - Recently - Around a Star Called HD 172555"
  (August 10, 2009)
• "Oceans on Venus; a Very Long Time Ago; Maybe"
  (July 15, 2009)
• "Wet Mars: New Evidence"
  (July 1, 2009)
• "Bottom of the South Pacific: 1,000 Times Less Lively"
  (June 23, 2009)
• "Ancient Lake on Mars - Maybe"
  (June 20, 2009)
• "Warp Drive Might Not Be Stable: Physicists Take Another look at Alcubierre's Work"
  (June 12, 2009)
• "When Worlds Collide: You Wind Up With a Hot Planet"
  (June 11, 2009)
• "Exoplanets With Water: Blue Clue"
  (June 1, 2009)
• "VB 10: Tiny Star, Big Planet, Exciting Possibilities"
  (May 30, 2009)
• "A New Way to Search for Life on Other Worlds"
  (May 28, 2009)
• "Warp Drive: Yes, it May Be Possible; But Don't Hold Your Breath"
  (May 7, 2009)
• "Gliese 581: Lightest Known Expoplanet (Caution! Geeky Content!) "
  (April 21, 2009)
• "SETI and More: Scientific Progress Goes 'BOINC' "
  (April 18, 2009)
• "Red Dwarf Stars: Not the Undesirable Real Estate We Thought?"
  (April 9, 2009)
• "DNA - A Universal Pattern? Could Be"
  (April 8, 2009)
• "Life is Left-Handed on Earth (Caution: Geeky Content)"
  (March 23, 2009)
• "Life on Ceres? Could Be"
  (March 5, 2009)
• "Exoplanets - Wired's Top Five Most Extreme"
  (January 27, 2009)
• "Gliese 581 c: Closest Match to Earth Outside the Solar System"
  (January 15, 2009)
• "Planets Circling Other Stars Photographed"
  (November 13, 2008)
• "Re-Thinking This Galaxy's Habitable Zone"
  (September 23, 2008)
• "The Purple Hills of Earth?"
  (September 6, 2008)
• "Faster-Than-Light Travel: Maybe"
  (August 14, 2008)
• "Diamonds: Ancient Crystals, New Speculation, and the Origin of Life"
  (July 28, 2008)
• "Earth: Filmed as an Alien World"
  (July 19, 2008)
• "Mars: Water? Probably; Life? Eventually"
  (July 17, 2008)
• "Phoenix Mars Lander: Looking for Life as We Know it"
  (June 12, 2008)
• "Life on Mars as a Threat - No Kidding"
  (June 8, 2008)
• "'Thar's Ice in Them Thar Plains!' - Maybe"
  (June 1, 2008)
• "Mars, Mostly"
  (May 29, 2008)
  (Routinely updated list of posts about Mars)
• "Serious Discussions of Warp Drive"
  (May 24, 2008)
• "Vatican Says: 'Belief in Aliens Doesn't Contradict Faith' "
  (May 14, 2008)
• "The Sun as a Swinger? Cardiff U's Title is Better for Mass Extinction Article"
  (May 12, 2008)
• "Interstellar Travel: Difficult, yes; Impossible; No - NASA"
  (April 30, 2008)
• "SETI at Home: A Serious Search for Extraterrestrial Intelligence"
  (March 29, 2008)
• "Methane in Extrasolar Planet's Atmosphere: A First"
  (March 21, 2008)
• "Rocky Planets May be Common as Dirt"
  (February 18, 2008)
• "A Serious Search for Extra-Terrestrial Intelligence: A New Wrinkle in the Maxwell Equations"
  (January 31, 2008)
• "Plate Tectonics, CO2, and Life on Other Planets"
  (January 13, 2008)
• "What Would a Galactic Empire be Like? 'The Physics of Extraterrestrial Civilizations' "
  (January 2, 2008)
• "Galactic Empires and the One Percent Rule"
  (December 10, 2007)
• "Galaxies and Grocery Lists: Keeping Life in Perspective"
  (November 22, 2007)
• "And Now for Something Completely Different: New Planets: Three Hot, One Not"
  (November 8, 2007)
• "Habitable Planets, a Rand Report"
  (August 23, 2007)