To go solar or not to go solar? Homeowners looking to save money on their energy bills have a number of factor to consider.

It's easy to get excited about installing solar panels on your house – particularly when you find out that state and federal rebates can cut the price almost in half.

But, as we've reported before, you might get more bang for your buck from far cheaper (and yes, far less exciting) fixes. Small things like weather stripping your doors, turning down the thermostat or upgrading your refrigerator, can put a dent in your utility bills.

Even if you've done all that, solar panels still might not pencil out. That's because of something called "tiered pricing", which is how most utilities calculate your monthly energy bills. The idea is that energy is relatively cheap as long as you stay within a certain amount. Exceed that, and you're in the next "tier," where the rate increases. At the next tier, the rate is even higher. The difference between top tier and bottom pier can be as much as 44 cents versus 8 cents per kilowatt hour.

That's why solar panels tend to make more sense for people with substantial energy needs – the big, air-conditioned houses, the heated pools, the multiple flat-screen TVs.

The higher your monthly utility bills without solar panels, the faster those panels will pay for themselves once they're installed. Plus, even if those panels don't meet the complete energy needs of your house, they may be enough to bring you down to a lower tier, where the rate is much better.

If you're interested in making your home more energy efficient, this handy and comprehensive online audit from the people at Lawrence Berkeley National Labs is a good place to start.

The Exploratorium turns 40!40 years ago, a San Francisco icon was born, the Exploratorium. The museum was founded by Dr. Frank Oppenheimer, a famous physicist who worked on the Manhattan Project. After a short career as a physics professor (he was branded a communist during McCarthyism), Oppenheimer was inspired to supplement and improve science education. After spending time touring European museums in the early 60s, he devoted the next few years to develop an interactive museum in the U.S. In 1969, Dr. Frank Oppenheimer received a $50,000 grant from the San Francisco Foundation to start a new kind of museum at the Palace of Fine Arts.

The Exploratorium opened quietly that fall, slowly changing the way science museums are organized and oriented to their audiences. It combined a living laboratory, art, and interaction under one roof; the result is a place where science is accessible and owned by all.

In celebration of this anniversary, the Exploratorium is hosting a number of events at the museum over this weekend. Plus they are throwing in quite a treat…admission is free all weekend (November 7-8). For a full list of activities and an exceptional history of the museum, check out the Exploratorium’s 40^th anniversary website.

Exploratorium After Dark: Electrifying Science with Dr. MegaVolt
When: Thursday 11/5, 6-10 PM
Cost: Free for members, $14 for non-members (Adults 21+ only)
Details: Blow your mind with the electrifying science of Tesla coils and Austin Richards, PhD—aka Dr. MegaVolt. This electrifying Exploratorium Science After Dark will feature Dr. MegaVolt jousting with 14-foot electrical arcs from his high voltage Tesla Coil.

Cutting Ice into One with a Motorcycle
When: Saturday 11/7
Cost: Free
Details: Imagine a big block of ice suspended from the ceiling of the Exploratorium. Now imagine a wire wrapped around the middle of that ice block from which is hung a motorcycle. Chill out with other skeptics and watch the motorcycle fall to the floor as the wire very slowly cuts through the ice, but bear witness—the ice block remains one whole piece!

Iron Science Teacher
When: Sunday 11/8, 2-3 PM
Cost: Free
Details: Cheer on the competitors in this zany science cook-off, where teachers compete before a live audience for the revered title, 'Iron Science Teacher.' In recognition of the Exploratorium’s 40th birthday, this special edition of our popular show features a secret ingredient closely related to birthdays!

Something Incredibly Wonderful Happens: Frank Oppenheimer and the World He Made Up – A Conversation with Author K.C. Cole
When: Sunday, 11/15 at 3 p.m
Cost: Free with admission to the museum
Details: Discover the never-before-told story of Frank Oppenheimer, physicist, educator, brother of J. Robert Oppenheimer, and founder of the Exploratorium. Believing that “without understanding, we’d all be sunk,” Frank Oppenheimer created the Exploratorium to be a museum of human awareness that combined art and science while encouraging play, experimentation, and a sense of joy and wonder.

Lawrence Berkeley Lab's TEAM 0.5 is capable of resolving individual carbon atoms in the honeycomb crystal structure of graphene. See QUEST's video The World's Most Powerful Microscope for more information. Image source: Nano LettersThe twentieth century’s most important physicist after Albert Einstein is almost certainly Richard Feynman. Known as much for his eccentricities as for his brilliance, he spent his adolescent spare time picking locks, translated Mayan hieroglyphics as an adult, and was one of the few people brash enough to attempt viewing the U.S.’s first atomic bomb test without protective sunglasses. Feynman’s chief scientific contribution was the development of QED, a fundamental and astonishingly accurate description of electricity and magnetism. However, he was also a champion of the practical, and in 1959 gave a gave a prophetic speech at Caltech to his colleagues entitled, “There’s Plenty of Room at the Bottom.” The speech described a rich world of possibilities that could arise if we only applied ourselves toward controlling matter on smaller and smaller scales.

Fifty years later, a new field of nanotechnology has exploded. At the cutting edge, researchers are successfully manufacturing everything from corporate logos to radios that are all small enough to be stacked end-to-end perhaps a million items long across the proverbial head of a pin. The advent of personal computers and smart phones has brought the power of such miniaturization into sharp focus for the general public. In a very real sense, we have all become bottom feeders. Below is a brief progress report on the state of the field.

Microscopes: The old adage “seeing is believing” was not lost on Feynman back in the late fifties. He noted that many of the most fundamental questions in biology could be readily solved if we only had the ability to see the molecules directly. Today, new inventions such as the scanning tunneling microscope (STM), the atomic force microscope (AFM), and the transmission electron microscope (TEM) have all achieved resolution at the scale where individual atoms can actually be seen and manipulated.

Miniature Motors: Perhaps the speech’s most imaginative scenario, due to Feynman’s friend (and graduate student) Albert Hibbs, was the concept of being able to “swallow the surgeon.” Feynman imagined that we might some day be able to construct robots capable of repairing or investigating the inner reaches of an ailing patient’s body. Mixing engineering and biology like this can run quickly into thorny ethical questions. Nevertheless, interesting progress has been made. Researchers in Alex Zettl’s group at UC Berkeley have recently constructed a nano motor, for example.

Information Storage: Using order-of-magnitude arguments, Feynman argued that the Encyclopedia Britannica could be squeezed into a pin’s area if the text were reduced by a factor of 25,000. He offered a $1,000 prize to the first person capable of printing one page of any book at this scale. Tom Newman, a graduate student at Stanford, first accomplished this in 1986 with an impressive reprinting of the first page of Dickens’ classic A Tale of Two Cities. Today, you can buy the book in its entirety for only 1.9 megabytes. For a high-end smart phone with 30 gigabytes of memory, you could perhaps hold 15,000 books within the palm of your hand. Not bad.

Then again, at the extreme limit, Feynman also reasoned that you ought to be able to squeeze the text of every book that has ever been written (now more than 32 million titles according the Library of Congress) within the confines of a single speck of dust. We still have a long way to go.

Prion diseases are neurodegenerative, attacking the brain. Could they be responsible for the recent wave of Zombie attacks across the globe? Original photo: digitalsextant. I’m a sucker for zombie movies; I’ve watched dozens of them. I am especially fond of the Resident Evil Trilogy, where the T-Viruses effectively restructure mortality and create a world of zombies. There is something incredibly satisfying with the zombie movie plot – a virus outbreak devastates a planet but a group of people are immune and fight to save humankind. Having the ultimate evil as a virus also makes it seem more plausible and compelling. Yet viruses and bacteria do not live in limbo. They are alive and under the right conditions can be killed. Which is bad news for Zombies.

But what if there existed a substance that acted like a virus or bacteria but wasn’t living? Medicine made a revolutionary leap during the time of Louis Pasteur in the mid 1800's. The inventor of food pasteurization and one of the founding fathers of microbiology – he was able to prove germ theory. Food spoiled and organisms got sick because of the growth of bacteria and viruses within them. Within sterile environments, viruses and bacteria could be killed off and food could be preserved or organisms could recover from illness or infection. Sterilization works on living micro-organisms. Prions, however, are not living organisms.

Prions are infectious proteins. For unknown reasons, these proteins refold abnormally and cause a domino effect in surrounding proteins which in turn mutate into stable structures. Prions will then cause tissue damage and cell death to surrounding areas. Prion diseases are neurodegenerative, attacking the brain and are characterized by "holes" in the tissue. The incubation time for Prion diseases is quite long. They usually surface later in life but after they surface, the diseases are rapid and fatal. Such examples of Prion diseases include Mad Cow Disease in cattle, Scrapie in sheep and Fatal Familial Insomnia in humans. FFI is a disease that literally takes away the ability to sleep and in a few months leads to death. The Book “The Family That Couldn’t Sleep” by journalist D.T. Max follows a family in Italy that passes this disease from one generation to the next over subsequent centuries.

Prions have been and still are a medical mystery. What causes them to mutate and aggressively eat away at the brain? How can they be stopped? Because they are not living they are highly resistant to sterilization methods. While viruses and bacteria can be eradicated on equipment through heat, radiation or chemical reagents, Prions are strongly immune. Maybe Zombies are not so far off after all – lurking in the shadow of medicine has been a mutation that is resistant, brain-eating and neither alive or dead. It has some serious similarities to the zombies I have watched over and over again on the big screen.

If you want to learn more about Prions and their history, check out Down to a Science’s next reading group which is focusing on the book The Family that Couldn’t Sleep or check out the book Deadly Feasts: The "Prion" Controversy and the Public's Health by Richard Rhodes. And one more thing – Happy Halloween!

This year's Wildlife Conservation Network Expo in full swing at the Mission Bay Conference Center.

It’s a sunny, fall day in October and I am driving into San Francisco. I pass the colorful Love Parade floats revving up without a glance of longing. I pass the turn towards Golden Gate Park for Hardly Strictly Blue Grass Festival without an ounce of FOMO (fear of missing out). I giddily park outside of Mission Bay Conference Center and enter the Wildlife Conservation Network’s yearly Expo. Parades and music will have to wait; I am ready to gorge myself on colorful wildlife and rock star conservationists. Each year I am more amazed and enthralled by this extraordinary event.

The Wildlife Conservation Network (WCN) was founded in 2002 in Los Altos by Charlie Knowles and Akiko Yamazaki. Their unique approach to conservation is based on the venture-capitol model and offers organizations expert networks, fundraising support, global exposure and Silicon Valley expertise. 100% of donations to WCN go to programs. It is an efficient system with measurable results and an excellent example of conservation action.

The Wildlife Conservation Expo is a dream come true for wildlife people, and after many years of attending, it feels like an international family reunion of cousins related by their passion for animals and the natural world. Flying in from 30 countries, including the mountains of Uganda, the savannahs of Zimbabwe or the steppes of Uzbekistan, they come together to share their miraculous projects. I marvel that I simply need to navigate the s-curved bridge from Oakland to be amongst this kin of conservation heroes.

The day consists of short and sweet speaking sessions from these 24 wildlife powerhouses, each one more inspiring than the next. Between sessions, participants visit the many tables featuring local, national and international groups and projects. The Oakland Zoo table was surrounded by such favorite groups as Africa Matters, Animals Asia, WildAid, Reptile & Amphibian Ecology International, Project Tamarin, Mountain Gorilla One Health Program, Red Panda Network, Elephant Voices, or our Teen Wild Guide’s favorite, The Saiga Conservation Alliance. Add in mingling with hundreds of like-minded people, and it is a day that can’t be beat. Oh, did I mention Jane Goodall is the keynote speaker? As I write this, I watch her graciously speak with participants, sign books and scratch the head of one of the Working Dogs for Conservation. Lucky dog.

At Dr. Jane’s presentation, she begins with her uncanny chimp-like pant-hoot greeting and reminds us that passion is the most powerful asset one could have. That if we all explored and exercised our passions, what a different world it would be. As usual, I leave WCN with new ideas, new reasons to be hopeful and renewed gratitude for WCN.

The 2010 dates have yet to be decided. Watch the website for details.

The Large Hadron Collider, if located in the Bay Area, would encompass a sizable piece of San Francisco. Image Credit: NASA.In about one month the world’s biggest science experiment, the Large Hadron Collider (LHC) at CERN in Geneva, Switzerland, will once again fire up. So now may be a good time to stop and remember what a stunning and ambitious project this is. Indeed, it becomes hard not to get lost in such an endless list of superlatives once you start noticing. I have gleaned a few below. See CERN’s website for more, or Jennifer Skene’s blog for a great set of LHC links.

She’s Electric: To power a standard light bulb you need 60 Watts (or 15 watts for an equivalent CFL). To power a small house you need an average of about a thousand watts. To run the LHC at full power researchers will need 120 million watts. Alternatively, you could run the LHC, supply electricity to a population the size of Berkeley, or simultaneously bake 60,000 Thanksgiving turkeys. You could only fly three 747 airplanes, though.

Life in the Fast Lane: A fundamental axiom of physics states that no information can travel faster than the speed of light. The LHC’s proton beams are no exception, but their speeds do approach light speed to within a fraction of a millionth of 1 percent. Such velocities defy comprehension. Suffice it to say that if we ever managed to accelerate a person to this velocity, time would warp so much that we could expect her to live for half a million years.

The Long and Winding Road: The LHC’s 17-mile circumference could make it a nice racetrack for a half-marathon, but don’t try racing the beam. When operational, protons will shoot around the LHC more than 11,000 times per second. Even more mind-boggling is the length of wire used in the construction of the LHC’s thousands of superconducting magnets. CERN claims there is enough wire wrapped up in these magnets to trace out more than six trips to the Sun and back.

OK Computer: When operational, the LHC is expected to generate 15 petabytes of data and simulations per year, which amounts to the hard drive space of about 30,000 high-end personal computers. At CERN in 1989, Tim Berners-Lee and Robert Cailliau revolutionized the world with their development of key pieces in the framework of the World Wide Web. The networks being developed to manage the LHC’s expected data have inspired talk of a similar revolution to come.

A Whole New World?: All of these wonders of physics and engineering have been developed for the purpose of one thing: to create a particle smasher with the capability of knocking two protons together with an energy of 14 TeV (trillions of electron volts). This is about the same energy that it takes to pick a grain of salt up off the floor. Compressed into such an acute space, however, it just might lend us insight into the most fundamental properties of our universe.

Now, if they can only get those wires hooked up correctly…

One of 20 solar-powered homes on display at the Mall in Washington D.C. This one is from the University of Kentucky. Credit: Mike MiskellyI was in Silver Spring, Maryland visiting my family last week, and had a chance to visit, with my sister Anne Marie and her boyfriend Mike, the 2009 Solar Decathlon. I’m used to seeing some unusual things on the Mall in Washington, DC—our nations backyard—but was quite impressed by the 20 solar-powered homes arrayed there last Saturday. Students from all over the world designed and built the houses over a two-year period, then disassembled them, transported them to the Mall, and put them back together.

The Solar Decathlon judges these houses in, of course, ten categories.

• Architecture — 100 points
• Market Viability — 100 points
• Engineering — 100 points
• Lighting Design — 75 points
• Communications — 75 points
• Comfort Zone — 100 points
• Hot Water — 100 points
• Appliances — 100 points
• Home Entertainment — 100 points
• Net Metering — 150 points

There are some interesting differences this year, compared to the last contest in 2007. Instead of charging a plug-in hybrid vehicle, as they did in 2007, teams now have to power a home entertainment system. The sponsors of the contest realized that electronic devices, like TVs, make up an ever-bigger share of a typical home’s electricity draw. That’s happening right now, while a plug hybrid car in most every driveway or garage is a thing of the future. A second new feature is that today’s solar houses are connected to the grid. The category “net metering” was not in the last contest. Teams earn points by sending more energy, created by sunlight, to the grid than they use from the grid. The ultimate goal for those of us the home performance field is that all homes become “net-zero” energy homes, or “net-positive,” meaning that the produce as much or more than the grid supplies them over the course of a year. A big problem with solar energy, as well as another renewable source, wind, is that power is created intermittently. Energy storage is necessary, and it is often expensive and not very efficient. With net-zero energy homes, the grid itself provides the storage capacity. When I lived in a Catholic religious community (Holy Cross Priests), the economics of community life were simple—take what you need and give what you can. Same for a net-zero energy house.

I wanted to take a look at the Team Germany (Technische Universität Darmstadt) home, the winners in 2007, but the house was in the process of being judged. Judges don’t announce when they will be visiting a house and which category they will be judging. Teams must keep, for example, the shower water in their solar homes at a precise temperature and flow rate all during the contest. No one knows when a judge will come to the door with a thermometer and flow gauge.

We walked by every house, and stopped at two—with the smallest lines snaking there way out front. (The Solar Decathlon expected as many as 250,000 visitors this year—looks like they made it.) We took a tour of the Iowa State and the University of Kentucky homes. I was partial to the simplicity and the day-lighting scheme of the Iowa house, which made use of simple pine siding and clerestory windows. Mike was more impressed with the Kentucky house, which had some pretty nifty fold up furniture and other creative uses of space. A member of the Kentucky team told us they were inspired by Shaker furniture. The house had wooden chairs, designed in Kentucky and made in Italy, that folded up to be hung on the walls, with decorative features that makes them pleasing to the eye. The Iowa house was made specifically with an older couple in mind. It has a simple layout and it is easy to move around in. Both the Iowa and Kentucky houses had big open showers in the bathrooms, with tiled floors and drainage. Energy efficiency and luxurious (though low-flow) showers can go hand in hand!

As of this writing (Wednesday), Team California, (Santa Clara University and California College of the Arts) is in the lead, with Illinois (University of Illinois at Urbana-Champaign) in second, Team Germany in third, and Team Ontario/BC (University of Waterloo, Ryerson University, and Simon Fraser University) in fourth. The categories of Net Metering, Engineering, and Lighting Design have yet to be judged.

Updates soon!

Kevin Cain, Digital Capture Supervisor for Maya Skies, demonstrates his innovative image-capture process that replaces expensive custom hardware with affordable consumer equipment.On this week’s TV episode of QUEST, we go behind the scenes of Tales of Maya Skies, the new film produced by Oakland’s Chabot Space and Science Center.  The half-hour film about Maya astronomy opens at the center’s planetarium on November 21.

The film is groundbreaking for a couple of reasons.  It’s the first time the Chabot center is using state-of-the art laser scanning technology to create one of its films.  For Tales of Maya Skies, a team of 25 people spent seven weeks scanning the ruins of the ancient city of Chichén Itzá, in Mexico’s Yucatán Peninsula.  This technology is widely used by Hollywood productions because of the flexibility it gives a creative team.  Once they’ve scanned a particular site, they can play with any one of its variables: they can create the illusion that the camera is moving in crazy ways; they can manipulate the light conditions, and they can change the look of the location in any way they want.

The creative team behind Tales of Maya Skies, made up of, among others, Emeryville nonprofit Insight, the San Francisco animation companies Digitrove and Palma VFX, the ARTS Lab at the University of New Mexico, producer Konda Mason and director Jin An Wong, are taking advantage of all the possibilities that the scanning of Chichén Itzá provides.  The audience will be immersed in full-color animations that go beyond showing the ruins of Chichén Itzá as they exist today.  Instead, through laborious historical research, the creative team has reconstructed what the monumental city must have looked like at its peak 1,200 years ago, with temples painted in bright reds, greens, blues and yellows, and incense burning and flags waving atop them.

By using the 3-D digital images created through laser scanners as the raw material for the animations in Tales of Maya Skies, the film is also breaking ground in more indirect, but perhaps even more important, ways.  Insight, the Emeryville nonprofit that oversaw the scanning at Chichén Itzá, as well as the Orinda-based CyArk, another nonprofit that worked on the project, are engaged in scanning irreplaceable sites around the world, documenting them for the benefit of the archaeologists charged with preserving them, as well as for generations to come, which might lose the real thing to natural disasters, war, or the passage of time.  CyArk’s co-founder, Ben Kacyra, has set out to use laser scanners to document 500 sites in five years.

But laser scanners, for all the wonderful detail, speed and flexibility they offer, are expensive.  They can cost anywhere from $10,000 to $150,000.  That’s why Kevin Cain, Insight’s director, has been testing an alternative system that can accomplish the same thing at a fraction of the cost. All the gear he needs is a digital camera, a flash and software, at a total cost of under $2,000.  Here’s how it works.  For every 32-square-foot swatch of an object, Cain takes 10 still photos with his camera and flash.  Then he uses the photos to reconstruct the object based on the brightness of each individual point on its surface.  The system is based on a principle of physics discovered in the 18^th century.  The high quality of today’s cheap digital cameras is what makes it possible to apply this principle to create an inexpensive image-capturing system.

“With this new technique, our ultimate goal is to be able to provide very low-cost, very usable results for archaeologists,” Cain said, “because until the price goes almost to zero, archaeologists aren’t going to be able to adopt it, just given the realities of their field.”  To illustrate those realities, Cain used the example of the work that Insight has done in Egypt for the past decade.  Each year they join a team of archaeologists for their field work at the Tomb of Ramses.  A complete yearly field season costs under $50,000, many times the cost of an inexpensive laser scanner.

Could a genetic test have told me I was at a higher risk for developing type 2 diabetes? Image source: aldenchadwickThis sounds contrived but it isn't.  A couple of weeks ago I was diagnosed with metabolic syndrome.  Right when I am in the middle of talking about genetic testing!

Metabolic syndrome isn’t quite as scary as it sounds.  Basically I am on my way to type 2 diabetes.  But if I eat better and get off the couch, I should stave off the disease and get better.

My question, naturally, is whether or not a genetic test could have told me I was at a higher risk for developing type 2 diabetes.  And whether I would have done anything with that result.

As you know if you’ve been following my blog, I took a 23andMe genetic test and have been writing about it since.  The image below shows what the front page of my clinical report looks like (click to enlarge):

According to the DNA checked in this test, I am in the average risk range for type 2 diabetes.  This doesn’t really seem to line up with my reality.  But I might not expect it to since these genetic tests are so limited right now.

This kind of test can be informative with the yes answer—yes I carry a certain version of a gene that might lead to a disease.  But the no answer isn’t that useful.  It doesn’t mean that they've looked at all the possible genetic differences that can lead to a disease and I don’t have any of them.  Basically it means that they didn’t find the specific genetic difference they were looking for.

Now I wouldn’t necessarily have predicted that any genetic test available right now could tell me a lot more than that.  Type 2 diabetes is too complicated for that and a whole lot more research will need to be done to get a genetic test useful to lots of people.

But still, this is probably what people are looking for with these sorts of genetic tests.  Will I get cancer, type 2 diabetes, Alzheimer’s, Parkinson’s, etc.?  For most of these cases, the tests can tell you a lot about rare forms of these diseases but little about the more common forms.

So the no answer didn’t really help me much.  Here I am on my way to being a diabetic and the test said I was at average risk.  Of course, I suppose I didn’t even need to take a test… all four of my grandparents came down with type 2 diabetes.  Like lots of these complex diseases, family history is the best predictor.

The second part of my question is a hypothetical one.  Let’s say they had a perfect genetic test that said that I was at an increased risk for type 2 diabetes.  Would it have changed my behavior?  I’m not sure but probably not.

I certainly wouldn’t have changed any of my behaviors when I was young.  I was invincible, remember?

Now that I’m a bit older, such a test might have influenced my behavior a bit.  I already knew about my risk because of my grandparents but my thought has always been that maybe I got lucky and didn’t inherit their tendencies towards diabetes.  But if they were tested and we shared the same genetic differences that led to type 2 diabetes, then I might be worried enough to change what I was doing.

Most likely though, my behavior modification wouldn’t be perfect.  What I’d probably do is keep watching TV and eating Twinkies but get my blood sugar tested more often.  Once I was headed for diabetes, then I’d modify my behavior and keep it at bay.  (I’m sure doctors scream into their pillows at night because of patients like me.)

This is different than some people’s reactions to other genetic tests.  For example, some women who find out they have the version of BRCA1 that greatly increases their chances of breast and ovarian cancer have a double mastectomy and/or a hysterectomy before there are any signs of cancer.

I might react much more strongly with a valid cancer genetic test.  Cancer is scary, nasty and not really reversible.  Type 2 diabetes is different.  You can start down the road, modify your behavior and then nip it in the bud.  Carpe diem and then pay the piper.

Bumps and ripples in the otherwise flat ring system of Saturn cast long shadows at equinox. Image credit: NASA/CassiniImagine a vast, flat plain spreading out before you for tens of thousands of miles in all directions, with no Earthly curvature to give the horizon its slightly finite look. Instead, it stretches seemingly to the infinite blackness of space in one direction, and slices straight into the streaky, wind-smoothed clouds of Saturn in the other…

Hard to imagine what it would be like to float just above the rings of Saturn, but what a sight it must be! As a kid, one of my favorite astronomical pass-times was imagining the view from other places in the Solar System.

Now imagine a towering bulge of frosty mist rising up out of this super-flat plane of ice chunks, literally the size of a mountain. Such is what was beheld by NASA's Cassini spacecraft last month–albeit, from a distance–when it turned its cameras to Saturn's vast rings during the few days surrounding Saturn's equinox (August 29, 2009), giving us a view never before seen.

Equinox on Earth, when the Sun is positioned directly over our equator, happens twice a year. Due to Earth's tilted rotational axis, as we orbit the Sun the latitude over which the Sun shines directly cycles north and south between the latitudes of the Tropics. On its way north to warm our (Northern Hemisphere) summers or south to leave us in the chill, the Sun crosses the equator on the equinoxes (Fall and Spring).

The same thing happens on Saturn, with two differences. First, Saturn takes nearly 30 years to orbit the Sun, so equinox comes only about every 14 years. Second, Saturn has its system of rings that encircle the planet directly above its equator, serving as a visible extension of the equator. At Saturn's equinox, the Sun is not only directly over the equator, but sunlight strikes the rings edge-on, like a flashlight shining on a flat piece of paper from the edge, the light just grazing over the surfaces on either side.

When this happens, any deviations from the flatness of the ring system—bumps and ripples–cast long shadows across the rings, making the features much easier to see. The same thing is seen on that piece of paper with shadows from creases and bumps leaping across the page.

As seen from Earth, equinox on Saturn means the rings appear to vanish as we look at them edge-on. This behavior puzzled astronomers long ago before they understood the rings for what they are. During the August 2009 Saturn equinox, however, for the first time in history we had a bird's-eye view of the rings during equinox, from Cassini. Cassini has been in orbit around Saturn for five years now.

Cassini spotted a number of prominent shadows trailing bright spots and ridges—bumps and ripples of different sorts rising above the ring plane.

Some of the bumps–icy ring material kicked up by the gravitational disturbance of a small moonlet inside the rings–were measured at over two miles high, the height of the Rocky Mountains. Other rippling features, such as long ridges running along the direction the rings encircle Saturn, are waves created by the gravity of moons orbiting outside the ring system. Still other types of disturbances observed are possibly caused by the impact of meteoroids or chunks of ice with the rings.

Saturn's rings are tens of thousands of miles across, but are extremely thin—perhaps no thicker than the height of a four-story building! So a bump or ripple as high as a mountain is a big deal!

Ah, to be on Saturn, now that equinox is here…