Tuesday, February 27, 2007

Very Early Americans

In an enormous variety of distinct fields of inquiry the same general pattern is becoming clear: there is no such thing as "right," the very concept needs to be replaced with "progressively less wrong." ~ Paul Grobstein

A Clovis point (about half way down the page) is a lovely piece of craftsmanship. Named for Clovis, New Mexico, where the first examples were found, it has also been considered to be the signature of the first people to come to the North American continent some 11,500 years ago. According to this theory, people came across the Bering land bridge near the end of the last Ice Age, found an ice-free corridor, and followed it into more temperate climes on the North American land mass. This group spread rapidly from the north to South America, thanks in large part to the advantages provided by the Clovis points which they developed.

A neat and tidy theory to be sure, but one that has been reconsidered of late thanks to recent discoveries and re-evaluations of old ones.

For starters, the idea of “ice-free corridor” has been considered a questionable way for anyone to get here. Tom Koppel's book Lost World points out that such a route would be difficult from a survival standpoint. There may be little or no ice, but there would also be little or no game to be had either. A trek of the length proposed would be difficult to imagine without sources of food. Mr. Koppel's own theory involves an earlier incursion, perhaps 13,000 to 14,000 years ago.

In Mr. Koppel's view, supported by evidence from digs along the Alaskan and Canadian coast, is that the immigrants came by boat, along a shore line that was ice-free. They would have fished and hunted, stopping on islands or on exposed shorelines when necessary. Much evidence, according to Lost World, is underwater now, because the water levels were much lower due to glaciation.

Then there are the Peruvian sites of human habitation that date from around 12,000 years. Even assuming some degree of uncertainty in the 11,500 year time frame, it is virtually inconceivable that humans could have progressed the length of North America and settled in South America in, say, a 500 year period.

Even the Clovis point is now being questioned. In a new paper, Michael Waters has reviewed the carbon dating of Clovis finds. Methods get better, and carbon dating is more sophisticated now, with considerably smaller error bars than in years previous. The Clovis period, it seems, was only about 300 years long, which is far too short a time to account for the spread of humans throughout the two continents. So, according to Mr. Walters, scientists should be looking for earlier tools, earlier habitations.

Perhaps they've found some. In Walker,Minnesota, archaeologists have found what appear to be stone tools of a more primitive make than Clovis. They date to 13,000 to 15,000 years ago. The problem is that even to those who found them, “they don't look like much.” This is always a problem with looking at a previously unknown primitive tool. Louis Leakey felt he had found such tools in the Southwest but was later found to be in error in the opinion of most scientists. These tools may yet turn out to be a disappointment.

But, if they are real, did these people come down the ice-free corridor, despite Mr. Koppel's theory that it was a sterile no-food zone?

There's another wrinkle about the Clovis points. One would expect to find some sort of pre-Clovis architecture in Siberia, where the North American settlers were supposed to have originated. In fact, nothing of the sort has been found there. But, it turns out that in France, there was a culture referred to as the Solutreans, who made points that appear to be direct precursors of Clovis. Some think it's possible that this group made their way across the Atlantic, pausing on the ice when need be, coming to North America as the true first settlers.

In fact, settlements have been found in the eastern United States, that may be older than Clovis. One has even yielded a point that appears to be a transition between the Souletrean point and Clovis. But it is always risky to form theories on a single data point.

It is intriguing that we seem to know more about the movements of the Neanderthals than we do modern humans in the New World. But, given that some of the most critical evidence may be underwater, that may be understandable. Techniques for finding such evidence is improving, and obviously, given finds in the eastern U.S. and in Minnesota, there are still finds of consequence to be located on dry land. There's only one choice for the archaeologists.

Yea, verily, dig they must.

Thursday, February 22, 2007

Enemy of the People

There are only two things that are infinite: the universe and stupidity, and I'm not sure about the former. ~ Albert Einstein

Seth Shostak, who writes a SETI column over at Space.com, wrote a thought-provoking little piece called “When Did Science Become the Enemy? In it, Mr. Shostak considers the negative attitude of Americans toward science. He sort of ties it down the general ignorance of what science does and the resultant fear that generates.

This attitude toward the sciences has always bothered me. Except for the brief post-Sputnik era, Americans have generally kept science at arm's length, regarding those who were interested in it as slightly weird people. Or worse, regarding them as somehow sinister.

The problem is part of a larger one, though. Americans have always been ones to give lip service to the idea of the importance of education. Despite this, we are loathe to pay the costs associated with providing a solid educational system. Our institutions of higher learning are considered more important as development leagues for the NFL and the NBA than as centers of learning.

It's pretty much been this way for a long time. The aforementioned post-Sputnik era was an aberration, when we realized the ramifications of a Soviet Union that was better educated and had more invested in science than the U.S. As a result, the country literally mobilized to emphasize science and engineering. Once we got to the Moon, we went back to our old ways. Prior to that, the Manhattan Project, the development of the atomic bomb, also caused the government to rally behind the cause of science. Before and since those events, science was seldom given a thought.

Interestingly, both those efforts depended heavily on foreign scientists, either escaping from Hitler's rule or being captured as a result of defeating that same Hitler. The Manhattan Project depended heavily on the likes of Szilard, Fermi, and Teller, while the space program was built by former V-2 builders like Werner Von Braun.

This is not to say that there are no American scientists; on the contrary, there are many talented researchers and theorists fully educated in our country. But to do so, they had to buck the odds, enduring the suspicion and outright animosity, at times, of their fellows.

Why are so many people like that?

I have trouble understanding it. I find many people are fascinated by new discoveries and great scientific tools like the Hubble Space Telescope. Yet there seems to be an inherent distrust of the people who make the discoveries and develop those tools. It's tempting to call it anti-intellectualism, but somehow that sounds like an oversimplification and smacks of taking a superior attitude – which would serve to justify the opinion of those who don't trust the scientists.

But, there is something to it, nonetheless. Last time I looked, somewhere around half of Americans favored Creationism over Evolution, and many were trying to either force the teaching of “creation science” in schools or block the teaching of evolution altogether. I have said on many occasions that I respect the religious faith of people, but when they attempt to inset their mystical beliefs into the educational system as science, they begin to lose my respect.

It isn't just religionists, though. Our society places more emphasis on the lives (and deaths) ofcelebrities like Paris Hilton or Anna Nicole Smith than it does on scientists probing the secrets of the universe, or, for that matter, than it does on poets, artists, or composers of serious music. Support for symphony orchestras in this country declines with each passing year. Why? Because the music they play is “high-brow”, and our society prefers the “low-brow” maunderings of American Idol.

There are still people on this planet who are striving for an educated society and excellence in the arts. I speak, of course, of the Asians. Whether our love of mediocrity will succeed in dumbing them down, as appears to have been the case in the former Soviet Union, or whether we'll find ourselves regarding them as the intellectual powerhouses of the world is difficult to tell.

I don't know if I'll be around in twenty or thirty years to find out, but I'm betting that the day will come when China is the preeminent center of knowledge in the world. That may or may not be a bad thing, depending on whether the current leadership can stop imprisoning its people and trying to block free exchange of information with the outside world. If they do, then a very dynamic group of people will be looking for new frontiers to conquer in a peaceful manner. If they don't, then a very dynamic group of people won't be so concerned about peaceful conquests.

Our society is fully capable of being the intellectual equal of any in the world. It's our choice whether we wish to do so.

Tuesday, February 20, 2007

The Bones Talk

Often, reading about some particular fossil or artefact makes me wonder how it came to be, and causes me to imagine an answer. ~ Jean M. Auel

The bones keep on talking to us ...

We Didn't Kill the Terror Birds

We're off the hook for another extinction. The “Terror Bird”, Titanis walleri, is often depicted as being a contemporary of sabre-toothed cats and mammoths and has long been thought to have gone extinct around 10,000 years ago. Titanis was a resident of North America, so, since this time frame coincides nicely with the arrival of humans on the continent, those early hunters were given at least part of the blame for having killed them off. It turns out we were way too late.

According to a U.S. team who studied rare earth elements within Titanis bones, the Terror Bird finished its terrorism about 2 million years ago, long before any hominids were doing organized hunting. But that wasn't all that the team discovered.

It had been assumed that the birds had migrated from South America to North America about 3.5 million years ago, using the Panamanian land bridge. It now looks as though they showed up about 1.5 million years earlier than that. This raises some serious questions because Titanis was flightless, and 5 million years ago there was water between North and South America. So how did they get here?

That remains a question for more research. It's possible that they could have floated across on natural mats, or they could have been decent swimmers. There is evidence that there were many volcanic islands scattered between the continents. It's possible that these carnivorous canaries could have swum the distance from one to another until they arrived in the north.

Another Possible Neanderthal-Cro Magnon Hybrid

As any reader of this space knows, I think the ongoing fascination with Neanderthals is almost as interesting as the people themselves. Once again, the idea of interbreeding has been raised, this time by a skull found in Romania. The skull has both modern and Neanderthal features and brings up the romantic notion again that we may have Neanderthal ancestors.

It is a slippery slope to find an ancient skull with a flattened face and other Neanderthal sorts of morphologies and extend that evidence into Cro Magnon-Neanderthal nuptials. The fact remains that no evidence of Neanderthal DNA has been found in ours, so, if there was interbreeding, it was either extremely limited, or the offspring were sterile hybrids.

The evidence is very thin so far. What is needed is DNA evidence from one of these skulls showing modern and Neanderthal properties. Unfortunately, it is often hard to get samples for DNA testing from such old skulls. Teeth are the best bet for DNA, but generally the skulls are incomplete or as in this other case, the fossil itself has not been carefully enough handled to prevent contamination.

The Return of the Hobbit

It's been a long time since I've written about the dwarf humans, regrettably known as Hobbits, found in Indonesia. At that time, conventional thinking seemed to be leaning toward the single skull that had been located as belonging to a microcephalic individual. This didn't sit well with the discoverers of the bones, but it was hard for them to refute because of two things. First, although they had bones of several small hominids, they had just the one skull. Second, it seemed unlikely that a creature with a brain that small could be responsible for the tools that were also found at the site.

Initial analysis of the brain case of the Hobbit seemed to confirm that it was a victim of microcephaly. A new study, though, claims to show that the brain, while decidedly smaller than mere dwarfism would require, does not appear to have characteristics consistent with microcephaly. So, what do we have here?

The answer is that no one is quite sure. Dean Falk, who conducted the newest analysis claims that the brain must have been “rewired and reorganized” so that the Hobbits could essentially do more with less. We need to keep in mind that, while Professor Falk's study does not indicate abnormality, it is something of a jump to say that the Hobbit's brain could have produced the tool-making technology evident in the finds.

If, in fact, Professor Falk is correct, though, it forces us to look at the evolution of the brain differently, because nothing like the Hobbit's brain has shown itself in our evolutionary history before.

Ah, science. The more we find out, the more questions we have to answer.

Thursday, February 15, 2007

Cosmic Clouds

It is almost possible to predict one or two days in advance, within a rather broad range of probability, what the weather is going to be; it is even thought that it will not be impossible to publish daily forecasts, which would be very useful to society.~ Antoine Lavoisier, 1743-1794

The debate about global warming has pretty well shifted from whether it is occurring to what is causing it. In the main camp are those who wish to lay the bulk, if not all, of the blame on humanity. In the other camp are those who think that other factors are at work over which we have little or no control. It is trendy to be in the former group; it may be more sensible to be in the second.

I cover this territory back in November in some detail. The crux of that piece was that we really haven't a clue about what makes the Earth's weather machine work. The 2006 hurricane prognostications certainly proved that. We can look back after the fact and make some reasonable guesses as to why things happened, but we don't seem able to use that information very well to make future predictions.

The problem is that the weather machine is complex beyond comprehension. There is an old saw about a butterfly's sneeze in Beijing causing a tropical storm in the Atlantic. That may not be far from the truth. Weather prognosticators have been fighting, and losing, the battle of predicting what the elements would do since the first hominid decided it was a good day for a hunt – only to come back with chilblains or little lumps from being pelted by hail.

In the article linked above, I mentioned the cosmic ray effect on climate, expressing some doubt, since cosmic rays have become the cause du jour for almost everything lately. But, the cosmic ray people are getting serious.

If you've ever used a cloud chamber, the theory should seem obvious. A cloud chamber is a device used to view the tracks of particles given off by a radiation source, like radium. What happens is that the chamber induces an atmosphere which is supersaturated with water (i.e., the air has a relatively humidity in excess of 100%). This can be done by compressing the air or cooling it, but the effect is the same. The little radioactive particles, in this case usually beta particles, bang into the water molecules and make them visible, leaving little tracks that are visible to the naked eye.

Cosmic rays are thought to do something similar in the atmosphere around us, colliding with various particles in the air and causing cloud formation. If you have more clouds, the sun's light is reflected off the cloud tops, cooling the Earth. If cosmic ray activity is decreased, due to, say, an increase in magnetic activity in the sun, then the number of clouds decreases, and the Earth warms.

An increasing number of scientists, looking at historic climate changes and even at periods of extinction throughout the long history of the planet, are beginning to think that clouds drive climate rather than climate driving clouds. So, if you affect cloud formation, you affect the heating or cooling of the Earth. One such group of scientists is going to put their money with their collective mouths are by running experiments using a CERN particle accelerator.

Of course, the mankind-is-evil crowd doesn't like this theory at all, as they don't favor any large-scale factors that could be impacting the climate. The problem with the human-generated climate change view is that it is a short-term outlook. One supporter, quoted in the article above, said he had checked cloud vs. climate records for the last 50 years in the UK and found a “small relationship.” That he found any relationship at all should have been significant to him.

What is worse is that the human-caused climate change crowd is fostering the idea that all we have to do is reduce CO2 emissions, and all will be well. If, in fact, global warming is caused by factors beyond our control, then we need to be taking action to deal with the coming changes. Right now, that's not happening. Even if we are a major factor in the climatic change, it is unlikely that, even if all carbon dioxide emissions were stopped tomorrow, the climate would happily reverse itself. The stuff is in the air now; it isn't going to disappear immediately.

So the real task is to start taking ameliorative measures to protect coastal areas against the rising of the oceans and to start figuring out how we're going grow food as currently arable areas become deserts. Presumably, when sea water is rolling down Wall Street, the powers that be will suddenly decide that something needs to be done. Worse, the industrialization-generated-warming crowd is allowing the politicians to get awaywith ignoring dealing with the coming change because of the implication that some simple actions will somehow fix everything.

It's potentially a much bigger problem with very complex solutions. And time's awasting.

Tuesday, February 13, 2007

Bringing Home the Dirt

For a successful technology, reality must take precedence over public relations, for nature cannot be fooled.~ Richard P. Feynman

The idea of sending a probe to another solar system body to collect samples and return with them is getting closer to reality, if the European Space Agency has anything to say about it.

It's not that we haven't gotten samples before. The Apollo missions brought back bunches of rocks from the moon, which are still being studied. Stardust returned with tiny little particles of comet and interplanetary space dust. It's cousin with the reverse-installed sensor, Genesis, returned with solar wind samples but crashed in the desert, leaving the science team with the daunting chore of reassembling and identifying the sample collectors. To date, it appears that some data will be saved, but how much is open to speculation.

Japan's Hayabusa probe may be bringing back some asteroid samples, but no one is quite sure at this point whether the sample was ever gathered. After a reasonably straightforward trip to asteroid Itokawa, things went awry. Mission controllers thought the satellite did its bounce-and-collect trick at least once and possibly twice, but returned data was ambiguous. It started on its return, which was projected to be this year, but something then went terribly wrong when fuel began leaking which had the effect of spinning the probe and losing maneuvering capability. Just to make matters nearly impossible, communications with the satellite were lost.

It's hard to find anything on the current status of the mission, since links to the Hayabusa web site all seem dead, but at least one badly translated summary tells us that contact was regained in 2006. Hayabusa is still due for a 2010 return to Earth.

{Whether the Japanese will have a space program operating to welcome it is somewhat up in the air as a lunar mission and a Mars mission have already been scrapped.)

Sample return missions, therefore, are no piece of cake. Of course, what everyone really wants is some good solid Martian dirt. If we could get hold of a nice little core sample (better yet, several nice little core samples), we might be able to determine once and for all if Mars ever hosted living organisms. It's no surprise, then, that the ESA is focusing on such a mission.

There are a couple of proposed designs that involve trying to hit Phobos first. Phobos makes a good target for a couple of reasons. First, it's easier to land and take off from a body with minimal gravity. Secondly, Phobos is very old, possibly made up of the primordial stuff that clumped together to make planets. That by itself makes the potato-shaped moon an inviting target.

One of the design, which itself has two possible permutations comes from Russia. The program is called Phobos-Grunt (grunt means “soil” in Russian, in case you're wondering; I certainly was), and the British, the folks who gave us the Beagle pancaking into the Martian landscape, has one tentatively called Astrium. The two approaches are rather different solutions to the same problem.

The Russian spacecraft, which is still bouncing between two designs (one with ion propulsion, one using conventional means) would land as one unit, poke around on the surface and conduct some experiments, grab some dirt, and return to Earth, presumably in the normal parachute-enabled manner. The proposed launch is some time in 2009 and looks set to go, although still having to decide between two propulsion models would make a launch in two years look like a tight schedule.

The British proposal would launch in 2016. This satellite would use ion-propulsion to get to Phobos and dispatch a probe to land on the moon's surface. The probe might do an experiment or two, but its main mission is to glom a little Phobos dirt and return to the main vehicle. That vehicle then returns to Earth and once again ejects the probe which comes to Earth and – here's the funny bit – crash lands, with no parachute or retro-rocket firing. I'm certain that the probe is designed for such a landing, but somehow it doesn't inspire one with a huge amount of confidence that we won't have Phobos-dirt scattered around a desert landscape somewhere.

Now, readers of this bit of the blogosphere might be aware that one of my concerns is developing methods for manned exploration with an eye toward colonization, to give humanity a chance at surviving its best attempts at messing up its home planet. But, sample return missions are very important, too. To begin with, the best way to find out a great deal about a place you may wish to visit is to study actual pieces of it. Also, it's the most economical way to continue to expand our knowledge of our immediate corner of the Milky Way.

So, let's go get some grunt.

Thursday, February 08, 2007

Digging Up Durrington: The Stonehenge Builders?

Anyone who has lived through an English winter can see the point of building Stonehenge to make the Sun come back. ~Alison Jolly

If there's anything that fascinates people even more than Neanderthals, it's ancient monuments, the older and more massive, the better. The Pyramids, the cities of the Incas, Mayans, and Aztecs, Easter Islandand, of course, Stonehenge all conjure up either a) prodigious efforts by non-technological groups of people to create immense structures with amazing precisions, or b) aliens.

We're going with a) here.

Stonehenge, built roughly 4,500 years ago remains, to my mind, one of the most impressive of these ancient construction projects for a number of reasons. First, the people doing the work probably were not organized on the level of, say, the Egyptians who built the Pyramids. Egypt was a relatively well organized state by the time their major projects were underway. The denizens of England were more likely to be decently organized tribes, but I've not heard of any infrastructure that could have pulled so many people and resources together at this point in English history. It's unlikely, for example, that there was a “public works” approach as there was in Egypt. On the other hand, it does mean that some central purpose was strong enough to unite the various villages to get the manpower to build Stonehenge.

Second, Stonehenge took a long time to reach its final form, roughly 600 years. It began as a regular henge, a raised circle of land surrounded by a ditch, containing only a circle of wooden poles. The structure was enhanced, improved, and increased in ways that suggest there were long-range plans. And, while there is debate over however much Stonehenge acts a a calendar, clock, or observatory, there are clearly some elements that line up with important celestial events, such as the winter solstice. Again, it takes planning to ensure that the structure will line up properly.

Setting aside the aliens, there has always been lively discussion about who built Stonehenge. Popular legend has the Celts or Druids doing the deed. Unfortunately, Stonehenge was finished about a thousand years before these people showed up. So, all those folks who show up wearing cloaks and speaking Gaelic or Elvish or whatever are having a good time, but they are being historically inaccurate.

We may finally have some idea of who the builders were or at least what they were like, though. A team of archaeologists, sponsored in part by the National Geographic Society, working at a place called Durrington Walls has discovered a village that existed before and during the time of the construction. The village could have held hundreds of people, making it the largest Neolithic village ever found in Britain. It seems, though, that it wasn't a permanent, year-round set of residences. Rather, it was used seasonally, possibly for rituals associated with the Salisbury Plain monument. Or at least, it may have been. So far, that is a speculative idea, but the team bases this on the kind of refuse left behind, which seems to indicate that a lot of feasting went on, given the number and type of animal bones left behind.

Interestingly, Durrington had its own henge, a wooden one, which was oriented differently than its more famous neighbor. Stonehenge is oriented with the winter solstice sunset and possibly with the summer solstice sunrise. Durrington is oriented in the reverse manner, toward the midwinter sunrise and midsummer sunset.

Since about 250 burials of cremated remains have been found at Stonehenge, there are those who think that Durrington Walls may have been to the Henge what Deir el-Median and Thebes were to the Valley of the Kings, a village of builders and of rites of burial. There are indications of a trackway or path that runs from Stonehenge and jogs up toward the Durrington village.

Interestingly, Julian Richards, whom I saw being interviewed on the BBC, does not seem to share the idea that Durrington Walls was a launching point (literally, for the river runs past Durrington toward Stonehenge) for funerary rites. Unfortunately, the interview didn't get into much detail, but I gathered he felt that Stonehenge was a celebratory place rather than just a cemetary.

The number of burials there do cover a considerable time, and Mr. Richards may be right in his view, but it is clear that Durrington Walls was a place that got very busy at certain times of the year. In fact, the nature of some of the pig teeth found there confirms that partying went on around the time of the winter solstice for sure.

There is a lot more digging to do here and much more to learn. For example, what was the relationship between the Durrington henge and Stonehenge? Could the feasting have been limited to events relating to the Durrington henge? What sort of celebrations and/or rites were really held at both locations?

At least we know they were having a good time while they were doing it.

Tuesday, February 06, 2007

Meanwhile, Back on Titan

The world is my country, science is my religion. ~ Christiaan Huygens

Want an idea how time just flies by? It's been two years since the Huygens probe landed on Titan.

Cassini-Huygens, as it was known at the time, arrived at Saturn after about a seven-year trip. Going to Saturn is daring enough, given all those ring-plane crossings, but going there to eject a probe to land on one of its moons is downright extravagant. But, right on schedule, Cassini, the size of a school bus, sent it's little partner Huygens, the size of a washing machine, hurtling toward Titan.

The result was an immense success, although at the time, some of the most valuable atmospheric data appeared to be lost due to a glitch in the antenna system. But, in one of those little miracles that occurs in the exploration of space, a bunch of radio dishes that weren't even supposed to be involved were listening. Because of the feeble signal from Huygens, even though they were listening, there was no reason to suspect that they would get any meaningful data. Yet, they did. No one scope got all of it all, but thanks to some very clever work, the Huygens team was able to piece the bulk of the data back together rescuing the seemingly lost information.

It's been that kind of mission.

Now, one of the standard quotes out of scientists when a satellite, probe, or rover goes somewhere is that it will take years to understand all the data coming back. And, too often, that's been the last the average person has ever heard of it. Primarily that's because the makeup of, say, Martian dirt isn't all that newsworthy to the mainstream media. So, unless you subscribed to astronomical journals or exobiology seminars, you probably didn't get to hear much about what was found.

The Internet has changed that. Thanks to numerous web sites that follow such activities, and with the judicious use of news aggregators, one can indeed find that scientists are, in fact, still learning things from data gathered years ago. Huygens is no exception.

The thing most people think of when they think of the Huygens landing on Titan are the spectacular photos of the moon's terrain. It was so familiar looking, with all the signs of liquid having flowed down to a plain that initially looked like a sea. There was a bit of disappointment when it turned out that there was no methane ocean to land in, but, as is often the case, the lack of one characteristic simply opens up more questions about what we did see.

It certainly hasn't hurt that Cassini itself has sent back reams of data about Titan. Coupling this information with what Huygens recorded is allowing the Cassini-Huygens team to build up a tentative picture of a fascinating place.

We hoped for an ocean; we didn't get one, but what we've seen is a much more varied place than we expected. It's amazing, really, that we keep being surprised. After two Voyager missions and the Galileo mission, we should have come to realize that we should expect these extraterrestrial places to be more interesting than expected. Titan is proving to be no exception.

Despite the fact that we haven't found a methane ocean, it's clear that liquid methane has played and probably still is playing a major role in Titan's life, just as water does here on Earth. For example, the pebbles that Huygens showed us, combined with the impact forces registered, imply that the probe landed in an “outwash”, a place where liquid (I keep wanting to say “water”, but that doesn't work at Titan's temperatures) flowed as, say, a stream might flow across a plain.

So where is the methane? Well, Cassini's radar has imaged what appear to be methane lakes. But methane would evaporate over time, so how do lakes get replenished? It must rain methane. One open question, then, is does it come down in drenching downpours or a sort of steady drizzle? That question may be answered by a new discovery by Cassini.

In a January pass, Cassini viewed a massive cloud, as big as the United States, over the northern polar region. This cloud has just become visible as Titan moves out its “winter” tilt so that light falls on the area. This cloud could be a massive methane rain storm, dumping lake-filling quantities of the liquid back to the surface.

Another Huygens finding shows that Titan is almost surely still geologically active, based on the detection of argon isotopes. This activity is probably in the form of “cryo-volcanos”, eruptions of water ice and methane, a theory supported by apparent “lava” flows, although this “lava” would be a sort of slush, not molten rock.

The fun is really just starting when it comes to discoveries about Titan. Cassini is going to perform 22 more flybys of the moon over the next 18 months, and, if the mission is extended (which is a definite possibility), there could be more. Every flyby has revealed more details that, taken with Huygens' data, fills in a few more pieces of the Titan puzzle.

Of course, it's a very large puzzle. But that's the kind scientists love.