Artist concept of NASA's Voyager 1, now
the most distant spacecraft from Earth.
Credit: NASAOne of the hardest things to explain to people is of the astronomical sizes and distances involved in our Universe. It's hard to explain because it’s hard for us–any of us–to really get our heads around the numbers, and what they really mean.

Along the road to understanding all things big and far away, I'll start small: the Earth.

Big as our world is, it's really only relative– but relative to what? It's just shy of 8000 miles in diameter. As a volume of space, that's about 268 billion cubic miles. In other words, were Earth a giant fish-bowl (an empty sphere), we could divvy up that volume between every human on Earth today, and each of us would get a cube of space about three and a half miles on a side.

How about that walk to the Moon? Do you remember from elementary school how long it would take you to walk to the Moon–IF you could walk to the Moon? The Moon is about 240,000 miles away, and while it takes light only 1.3 seconds to cross that distance, walking at a speed of 3 miles per hour it would take you about nine years to get there. That's equivalent to walking around the Earth's equator ten times.

Next step out might be Mars. At least, NASA's talking about sending people to Mars next–after a return to our Moon in 2019 (note that in this plan, it will take us longer to get back to the Moon that it would to walk there…). Walking the distance to Mars, even when it's at its closest (35 million miles) would take well over a thousand years–so the walking tour is out. At NASA-speed, it takes about 7 months to get a spacecraft to Mars.

One of the quintessential distances when talking about the scales of space is that old favorite: "Pluto distance." About forty times farther from the Sun than the Earth, a walk to Pluto would take an appalling 170,000+ years. At the speed of NASA's New Horizons spacecraft, which is currently past Jupiter and heading toward the distant dwarf planet at 50,000 miles per hour, it's about a ten-year journey. And New Horizons is the fastest spacecraft ever hurtled off into space.

To top off this blog (because there isn't nearly enough space in here to go much farther up), I'll leave you with space exploration's greatest up, up, and out story: Voyager 1. After 30 years in space, Voyager 1 is now a hundred times farther from the Sun than the Earth–that's two-and-a-half times farther out than Pluto! About nine billion miles.

Okay, now for the big finale. So, Voyager 1 is nine billion miles out, and it's taken it 30 years to get there. Hypothetically, if Voyager 1 were bound for the nearest star in space to our Sun–the Alpha Centauri system–then the portion of that journey it has now completed is equivalent to someone on a road trip from Oakland to New York City who has gone a single mile!

Coming up in a future blog: Mile Two.

Benjamin Burress is a staff astronomer at The Chabot Space & Science Center in Oakland, CA.

Great Whites get all the attention, but the waters of the San Francisco Bay are teeming with other, smaller sharks (like the leopard shark), who occupy the top spot on the Bay food chain. Where do they live? What is their relationship with sharks on the coastal waters? How do their social structures work? How many are there? There are many unanswered questions about the Bay's sharks, but in order to study these animals, researchers have to catch them first.

The Aquarium of the Bay is launching a program to learn more about these sharks. They are sending out their collection boats to catch, tag, and release as many Bay sharks as they can find. Next would be a campaign to get Bay Area fishermen and others to report the tags they find, and create a database. Lastly, researchers will launch a second round of tagging, using acoustic tags that respond to sensors already placed around the bay (and typically used to track salmon populations).

You may listen to the "Sharks of the San Francisco Bay" Radio report online, as well as find additional links and resources. Also see additional photos for this story.

Amy Standen is a Reporter for QUEST and Radio News at KQED-FM.

According to the National Science Board, Americans are pretty interested in science– but not all that informed about it. And in our knowledge-based society, the Board adds, this lack of understanding can have implications.

But what does that mean? What don’t people know? What would they like to know? And what difference would it make?

Matt Nisbet, a communications professor at American University, spends his life thinking about how people understand science. In late July, he paid the Exploratorium a two-week visit as part of our Osher Fellowship program, and shared some of his ideas about what it means to be "science literate."

Do YOU know why polarized lenses are better
at shading your eyes?There are different ways of viewing science literacy, Nisbet says. One person might think of it as having practical knowledge that can help our understanding of everyday experiences: "calories" actually mean "energy;" rain is water that once evaporated from the earth; polarized sunglasses work so well because ________ (can you fill in the blank? if not, try the link below). Another person might view "literates" as folks who understand the process of science enough to know why researchers often disagree, and are able to interpret scientists' differing viewpoints. Still another person might say that a scientifically literate citizen is one who understands science in relation to larger, more politicized issues, like climate change or stem cell research, and whose knowledge might therefore affect voting or other societal activities.

Matt pointed us to the National Science Board's annual report on public attitudes and understanding of science and technology. Some of the results cited in this report are fascinating: for example, Americans overwhelmingly say that science makes their lives happier and more comfortable. At the same time, less than half of us know that electrons are smaller than atoms, and even fewer realize that antibiotics don't kill viruses. Is there a conflict in having this trust in science while lacking an understanding of some of its basics?

As someone working at a science education institution, I'm interested to know: What kind of knowledge makes you feel scientifically literate? What role does understanding science play in your life?

P.S. Polarized lenses shade your eyes well because they absorb all light rays except those that are moving in a certain direction. You can see this for yourself by doing a little hands-on investigation with your polarized shades.

Robin Marks is a journalist and science writer who currently serves as a Multimedia Projects Developer for the Exploratorium, a hands-on museum of science, art, and human perception in San Francisco, CA.

Watch Your Back in the Mangrove Forest

Bengal Tiger -original photo by: Paul MannixMosquitoes are not the only ones that appear to consider humans a main protein source; Tigers in the Sunderbans Preserve
in West Bengal, India, also find them to be easy prey. Some report that close to 300 people have perished in recent years as a result of these cats.

The Sunderban Preserve expands 1000 miles along the Bay of Bengal. In this ecosystem, twice a day the tide rises and salty sea water floods the islands, sandbars, and forests. During high tide, the mangrove trees sit halfway under water, providing homes for fish and other animals.

One remarkable member of this web of wet life is the endangered Bengal Tiger. Some sources state that 500 to 600 tigers find a home in the region, making it the most densely populated tiger habitat on the planet. These tigers manage to live half on land and half in the water, looking for every kind of food source opportunity on land and sea. One such opportunity is humans in boats. As the local people go out in search of fish, wood and honey, they fall prey to these incredible swimmers. Tigers are said to approach a boat or dock so stealthily that they can nab a human lunch without anyone else even hearing and can swim after a boat like a dog runs after a car.

The government and various organizations have issued masks to the villagers. These masks are worn on the back of the head in an attempt to deter a predator that tends to attack from behind. Tigers seem to have learned their way around this and go for a side attack.

Why are these tigers man-eaters? There are many theories and not much research.

The villagers themselves also have a variety of theories on the subject, but most agree that these tigers are great and spiritual beings and deserve to be revered. They worship a tiger god called Daskin Ray and a forest goddess called Bonobibi. They celebrate these gods and pray to them before going out into the forest. They believe the tiger is a protector of the forest, guarding the other plants and animals. They believe that without these man-eating beings, their forest would suffer from increased illegal gathering and poaching and that tigers are a crucial part of the web of life and their lives.

Are there other reasons these tigers prey on humans? What do you think?

The Oakland Zoo works with an organization called Saving Wild Tigers (www.savingwildtigers.org). Our donations go to reparations and scholarships to families that have lost a member to a tiger attack. They feel this offering keeps families and community members in good standing with the tigers, which results in successful conservation of these cats.

Amy Gotliffe is Conservation Manager at The Oakland Zoo.

The Hubble Deep Field: The galaxies in this image
are really far away, but not as far away as the edge of
the universe.

I am going to spend the next couple of months addressing the questions asked by readers at the end of my late-July post. I'll start with the question that prompted the solicitation to begin with. Two months ago, my friend Taron emailed me to ask "How large is the universe?"

As with most questions about science research, this seemingly simple question actually has quite a complicated answer. It is complicated for several reasons:

1. We don't really know the shape of space or the complete history of the universe
2. We can only see a fraction of the universe
3. We don't have any idea how large this fraction is

A lot of research has gone into trying to answer problem numero uno. One of the main goals of my research, and cosmology research in general, is to better understand the history of the universe. There are still a lot of details waiting to be sorted out, but we do have a pretty good outline of how events unfolded.

One of the main building blocks of our understanding of the history of the universe is a theory called inflation. In inflation, the very young universe experienced a sort of explosion, causing it to grow so fast that light itself couldn't keep up. Because it happened so fast, we can't measure how much space grew during inflation, leading us to points #2 and #3.

Points #2 and #3 are impossible to answer because we rely on light to carry information to us from the far reaches of space, and light can only travel at the snail's pace of 186,000 miles in a second. This is all fine and dandy when making a call on your cell phone, but observing the far reaches of the universe can become a real test of one's patience. If I were to chat with an alien from the nearest star, I'd have to endure a pause of several years for a response after every question. If I want to know what's happening in some of the most distant galaxies, I have to wait BILLIONS of years.

Research has shown that the universe is about 14 billion years old. Going back nearly this far, we see the oldest photons in the universe, from the cosmic microwave background. If I were to half-heartedly attempt to answer Tarons question, I would simply say that this background is the edge of the OBSERVABLE universe and call it a day.

This over-simplification misses the mark in several ways. First, the info we get from the cosmic microwave background is a bit outdated, to say the least. It tells us about the universe as it was 14 billion years ago, and things have changed quite a bit in that time. The spots in the cosmic microwave background have since receded from us even further and have evolved into stars and galaxies in that time. If we were able to measure the distance to those stars and galaxies now, without the inconvenience of the speed of light, we'd measure a distance of 46.5 billion light years.

The second way in which this over-simplification is unsatisfactory is that it ignores all that lies beyond the observable universe. We know from inflation that the universe is much larger than what can be observed, but we have no idea of how much larger. In fact, it is probably impossible to ever know what lies beyond the observable universe since we cannot retrieve any information from those far reaches of space.

Finally, using the distance from Earth to the cosmic microwave background almost implies that we are at the center of the universe. In reality, the cosmic microwave background will appear equally distant when observed from all points in space, and everyone will appear to be at the center of a universe 14 billion years old. Each point in space is just a different reference frame, each having its own visible region of the cosmic microwave background and its own visible population of galaxies.

To be honest, because of these complications, I don't even bother thinking about the size of the universe. Instead, I think in an easily measured quantity called redshift. The way I see it, the fact that we are limited to a single reference frame and the finite speed of light is part of a game. To ask what lies beyond this set of rules is to open the whole philosophical can of worms that is metaphysics, and I'm not the one to do that.

Kyle S. Dawson is engaged in post-doctorate studies of distant supernovae and development of a proposed space-based telescope at Lawrence Berkeley National Laboratory.

An Associated Press story that I read in the Contra Costa Times on Wednesday pointed to one more negative effect of our nation's conspicuous power consumption. The National Fire Protection Association reports that the number of college dormitory fires has grown from 1,800 in 1998 to 3,300 in 2005. Thirty-nine students died in fires between 2002 and 2005. The reason for the increase in fires? Students are plugging in more electronic devices, including microwave ovens.

When I packed my bags in Maryland and moved to Indiana for college in the late 70s, I brought clothes, a clock radio, and a turntable with some early Springsteen and Steely Dan albums and that's about it. I lived in Carroll Hall at Notre Dame. We were regularly awakened by a fire alarm at 3 a.m. caused by an overheating boiler in the 100-year-old-plus building. No one was ever hurt, but it did lead to some interesting revelations––like who was entertaining overnight guests, a no-no at the Catholic school. (Sorry Billy Joel, but some Catholic girls don’t start much too late.)

In 1977, a fire at a dormitory at Providence College, in Providence, Rhode Island, killed 10 students. It's not known how the fire started, but it probably began with Christmas decorations. The story made headlines across the nation, and now most colleges and universities have strict rules limiting decorations in dorm rooms.

In 1999, Home Energy reported on a success story that combines energy efficiency with fire safety (www.homeenergy.org/archive/hem.dis.anl.gov/eehem/99/990310.html). Residents in Milwaukee, Wisconsin turned in halogen torchieres, a known fire hazard and energy hog that produces much more heat than light, for Energy Star energy-efficient CFLs. Home Depot gave out close to 700 energy-efficient bulbs in the first hour and a half. Because of many efforts such as the Milwaukee project, halogen torchieres are becoming rare.

This is the time of year when students from all over are moving more and more electronic equipment into their dorm rooms, sometimes connecting them to old and overwhelmed power grids. It seems like when one problem gets solved, another one steps in to take its place. Increased household electronics energy use–and more dormitory fires––have overtaken gains in appliance efficiency. But we've tackled problems like this before and we can do it again.

Jim Gunshinan is Managing Editor of Home Energy Magazine. He holds an M.S. in Bioengineering from Pennsylvania State University, State College, Pennsylvania, and a Master of Divinity (MDiv) degree from University of Notre Dame.

NASA has created a Centennial Challenges series – contests for everyday people to develop new technologies that may offer inspiration for the space agency. The most famous of these is the space elevator challenge, where teams create a solar powered elevator prototype. The one that gets to the top the fastest wins. Others include space gloves and lunar landers. Quest looks at this month’s competition: personal aircraft.

If you've ever found yourself stuck in Bay Area traffic, you've probably found yourself wishing you could fly right over it. Flying cars are usually the stuff of science fiction, but a group of engineers at NASA is hoping to change that. They're sponsoring a technology contest to revolutionize small planes – and it's open to the general public.

With congestion increasing in the Bay Area, many argue we'll need new innovations to tackle it, including mass transit and personal air vehicles. What do you think the future of transportation should look like? Do you think government agencies like NASA should spend more on research?

You may listen to the "NASA Flying Car Challenge" Radio report online, as well as find additional links and resources.

Lauren Sommer reports for QUEST and Radio News at KQED-FM.

All last week my partner and I savored a ratatouille made from a rather large and unique zucchini. What made this particular zucchini special? The answer has to do with soil enzymes, deforestation, and Skippy peanut butter.

My zucchini began its life in a bountiful test garden at the DriWater factory in Santa Rosa, from where I picked it during a recent tour of the facility. DriWater is a rather ingenious local invention—a gelatinous substance consisting of 98% water and 2% cellulose gum– that is used for time-release irrigation.

I visited the factory along with staff and participants from our Students and Teachers Restoring a Watershed (STRAW) Project, who use DriWater to irrigate the young native plants at many of our restoration sites until they become established. It's been a boon to the Project, allowing us to do restoration in areas without readily accessible water supplies.

How does it work? During restorations, students insert the DriWater gels into tubes that are buried next to the roots of each baby plant. The gels are about a foot long and resemble gooey, translucent sausages (As you can imagine, kids love working with it… and it's pretty amusing for adults, too.) Here's where those soil enzymes come in: the cellulose binding the water is gradually broken down by the cellulase enzymes created by bacteria in the soil, releasing the water directly into the root zone and providing moisture to the plant for two to three months. It's an efficient delivery system: A quart of DriWater is equivalent to about 6-8 quarts of liquid water, because little is lost to runoff or evaporation.

During our tour Harold Jensen, the company’s Research & Development Manager, told us about the origins of DriWater. Back in the ‘60s, Mr. Jensen was deeply affected by a visit to a Northern California logging operation. He became alarmed about the impact of deforestation and a lifelong devotee of native plant restoration. A further turning point came when he met chemist Lee Avera, who had worked for many years for the Skippy Company, developing the process that keeps your peanut butter from separating. In his retirement, Avera developed a gel with water-holding properties. The two men recognized the potential of the invention for reforestation work and founded the DriWater Company in a former apple processing plant in Sonoma County in 1992.

Listening to Mr. Jensen, it's easy to see that for him DriWater has world-changing potential, from conserving water, to facilitating farming in areas crippled by drought, to supporting massive reforestation on a scale to help mitigate global warming.

On a much more modest level, it can water your houseplants when you're away on vacation or (and I speak from firsthand experience) help raise a pretty impressive zucchini.

Ann Dickinson is Communications Manager for The Bay Institute (www.bay.org), a nonprofit research, education, and advocacy organization dedicated to protecting and restoring San Francisco Bay and its watershed, "from the Sierra to the sea."

When a contest to name our newest penguin at the Steinhart Aquarium came around, I was more than excited. The prize after all was a picture with the chick and a rare opportunity to get close to an African penguin. My strategy for the contest was simple – submit 25 entries. Lo and behold, a few weeks later one of the judges asked me about one of my submissions – Safara. The name which means Fire in the Wolof language was deemed a perfect fit to dub the spirited chick.

I met Safara in the back of the penguin enclosure a few days later. She was walking around in her pen with her brother Dunker close at hand. Both birds resembled full grown penguins in girth, however, their markings belied their younger age. While adults penguins are full black and white, chicks have lighter coloration. My heart was beating hard when Pam, our penguin caretaker, prepped me for the encounter. I picked Safara up nervously and placed her, with Pam's help, so that her feet rested on one forearm while I folded her against me with the other arm. Once she had solid footing, she settled in and took everything in stride. Pam explained to me that penguins like support for their feet while being held. I also learned how their heat escapes their body. Safara’s feet were hot against my skin! The sensation of her webbed feet and silken feathers was fascinating. Much of the time, I forgot to look at the camera because I was so taken with holding her!

Safara has been the only female chick born at 875 Howard Street. However, over the past few months, the Academy's African penguin colony has grown from eight to 13 birds. The Steinhart Aquarium is involved with a nationwide program– the Species Survival Plan– that facilitates the trade of captive bred penguins between zoos and aquariums in order to minimize taking birds from their natural habitat in Africa for display purposes. Howard, named after our building, is the first of the brood and is known for his booming voice. Dunker, named after the Aquarium Veterinarian, is the second eldest. Domino, who was named by an Academy member, was born shortly after Safara. All of these penguins now reside in the penguin tank and can be recognized by their exuberance and orange wing bands. Our newest chic, who is yet to be named is still being hand raised behind the scenes. When it is large enough, it will join the other youngsters in the penguin tank. All the penguins will eventually reside at the end of African Hall in the new Academy. The penguins are an iconic part of the Steinhart Aquarium and fuel many questions. Answers to frequently asked questions can be found at http://www.calacademy.org/aquarium/penguin_facts.php. I know my curiosity was piqued after meeting Safara, up close and personal.

Cat Aboudara is the Special Projects Manager at California Academy of Sciences and works in the public programs division. The Academy is a wonderful fit for her because of her curiosity about the natural world and her experience in working with native California wildlife.

Living in the bay area with two school-aged sons, you'd think the news that Barry Bonds broke the all-time home run record would have been a big deal in our house. It wasn't. My kids focused on the steroids instead of home run number 755.

This got me to thinking about fair and unfair advantages in sports. Very few people would argue that Barry Bonds was playing fair if he really took steroids so he could hit the ball farther. Or that bike riders in the Tour de France were playing fair by blood doping. But what if someone has bigger muscles or is blood doped naturally? What would be fair or unfair then?

The reason I got to thinking about this was that there actually was a case in sports of natural blood doping. The idea behind blood doping is that you can increase your endurance by increasing your number of red blood cells. One way to do this is to get a blood transfusion. Another way is by taking the hormone EPO.

EPO is a natural hormone that tells blood stem cells to make more red blood cells. EPO does this through a protein called the EPO receptor. And like any protein, the instructions for making the EPO receptor are found in a gene.

Back in the 1964 Winter Olympics, there was a Finnish cross-country skier named Eero Mantyranta. Eero won two gold medals so easily that people thought he must be cheating. But he wasn't.

Eero had more red blood cells than the average person because of a small change in his EPO receptor gene. His version of the EPO receptor thought that EPO was always around so his body kept cranking out new red blood cells. He was genetically blood doped.

Now imagine that Eero is a bike rider in the Tour de France. He would have naturally higher levels of red blood cells and so would be like those bike riders who were blood doping using EPO. Except the judges couldn't disqualify Eero for EPO use because he wasn't using it.

Now imagine a ball player with a certain version of the myostatin gene. When this gene isn't working right lots of animals including mice, dogs, cows, and people all develop large muscles. Should this myostatin-challenged player be allowed to compete? Or should other players be able to take steroids to level the playing field?

Of course this takes us down a slippery slope. Many athletes have versions of genes that make them run faster, gain more muscle mass, have better endurance. Should those of us not lucky enough to get these genes be able to compensate by taking the right medicines? Or using gene therapy to get the same genes? Is sports competition more about working hard, drive, and determination or the luck of the genetic draw? Or both?

Dr. Barry Starr is a Geneticist-in-Residence at The Tech Museum of Innovation in San Jose, CA.