Earth's coordinates and the Celestial SphereI’m dusting off the plastic tub where I keep all the materials for my Celestial Navigation class, in preparation for teaching it again, starting March 4. It’s not a certification course for learning how not to get lost at sea, but an introduction to astronomy spun up with the theme of that ancient practical use for astronomy.

Though I’ve been teaching this subject since 1996, I was delighted to run across a pair of antique sextants purchased in the 1940s by Earle Linsley, Chabot’s second director, for use in his Celestial Navigation class!

Anyway, it’s a special topic for me as it blends my interest in astronomy with my long time fascination for things nautical: ships, exploration, adventure, and global geometry.

Fixing one’s position on Earth is one of the oldest practical applications of on-the-go astronomy (maybe not as old as working out the seasons and establishing standard periods of time—calendars—but possibly a contemporary craft). Long have sea-faring cultures in the Northern Hemisphere used Polaris to mark north and determine latitude. In the Southern Hemisphere, without the trusty North Star in view, navigators such as Pacific Islanders crossing that vastness in large canoes nevertheless memorized the locations of other stars at different times of the night and year to steer their courses from island to island.

Arab caravans crossing the Sahara desert used Celestial Navigation so as not to get lost on the endless waves of sand dunes. The astrolabe—an instrument used to measure star altitudes to help plot position—was developed originally by Arab desert caravan drivers, not for sea-faring ships!

How does it work, in a nutshell? Well, more recent Celestial Navigation techniques—the kind portrayed by sextant-wielding navigators plotting lines and circles on paper charts—boils down to the older concept of the Line of Position. If you can see and identify a landmark somewhere on the horizon (a mountain, an island, the end of a peninsula, an exceptionally large and well known tree), and you can measure what direction it’s in (e.g., with a compass), you can draw a line on a chart through that landmark running in the measured direction, and you can reason that you must also be located somewhere on that line. If you can plot another line for another observed landmark, then you can reason that you must be located where the two lines cross. Get it?

Using stars as "landmarks" was the leap from land-based positioning to Celestial Navigation. Imagine a given star as the top of a ridiculously tall landmark, or lighthouse, rising high above the point on the Earth it sits directly over—the star’s "geographical position." The angle you measure between the star and the horizon (the star’s "altitude") depends on how far from that spot you are. If you’re at the star’s geographic position, then it’s directly overhead and makes an angle of 90 degrees with the horizon. The farther you are from that spot, the lower in the sky you will measure the star.

The key is to see that for any specific altitude measured for a star, you must be located somewhere (anywhere) on a giant circle on the Earth that is centered at the star’s geographic position. It’s like standing a certain distance from a flagpole and measuring the angle to its top: you’ll get the same measurement from anywhere along a circle drawn around the flagpole, but step closer to or farther away from it and the angle changes.

Measuring a single star’s altitude gives you a circle of position on Earth, somewhere on which you are located. Measure a second star and draw its circle of position and the two circles will cross each other at two locations—and you can reason that you are located at one of the two. Measuring a third star and a third circle of position should clinch the deal, marking your terrestrial position where the three circles intersect.

Modern GPS works similarly by measuring your position relative to several orbiting satellites, using the time delays in radio signals between satellite and GPS receiver to calculate a sphere of position surrounding each satellite. You are located somewhere on that sphere of position, and where multiple spheres intersect at the same point, there you be.

So, where are you today?

Wine making is indeed an art form, but it is increasingly becoming more scientific. I knew growing wine grapes requires a lot of attention to detail — there is the terroir, pests and diseases and all those microclimates. But who would have known, driving down Hwy 29, the main thoroughfare through the Napa Valley, that many of those vineyards are totally wired.

In our radio story, we feature the stylishly high tech Vineyard 29 and the Robert Mondavi Winery, but scores of other wineries are using a similar toolbox of technology to help them monitor the soil's water content to grow better grapes. The technology ends up conserving water, too. Remote sensing, ground penetrating radar and satellite technology have helped Mondavi cut back on water use by 30% in recent years.

Winemakers are using some of the same technology that NASA uses to study Mars and engineers use to build hi-rises and freeways. A typical toolbox includes multi-spectral imaging, weather stations, neutron moisture probes, and pressure bombs and there is a plethora of newer technologies in the pipeline. But enough with all the high tech gizmos. How does wine from high tech vines taste? The answer might be found in the success of the winery. Mondavi has won numerous awards over the years and there is a two-year waiting list just to purchase Vineyard 29 wines.

Check out our slide show to see some of these technologies or listen to our radio report on high tech in the vineyards.

The pilot project at UC Berkeley called Mobile Millennium uses cell phones as data points to show traffic patterns in real time.

To become an early adopter of the technology, you must have an unlimited data plan on a mobile phone with a GPS system. If you have that, you can sign up here.

Project leader Alex Bayen says that it's not just a breakthrough in how we can gauge traffic, but also a scientific breakthrough – that is, it was a challenge to take random data points, some in motion, some not, and to turn them into usable traffic information. This is how Alex Bayen put it.

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And he adds that, as cell phones get more memory and more devices on them, they will become more central in our lives.

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The science of place-based reporting is a burgeoning field. A program at UCLA, for example, uses cell phone information to create a personal environmental risk assessment and a UC Berkeley study monitors currents in the Sacramento River.

Listen to the Dialing in on Traffic radio report online.

Recently during "girl's day" with my mom – my mom made a comment that made me take a second take about technology. I was texting on my iphone and she tsked under her breath and said; "People don't talk anymore, it's all text this and email that, soon language will be obsolete!" My first instinct was rebuttal, after all email, texting and cell phones all facilitate communication. But she had a point, communication, as she knew it back when she was my age is going the way of dinosaurs. Instead of simply writing a letter or speaking to someone in person, many people prefer facilitation with technology.

All during this week, I have been seeing reminders that communication is powering ever new and faster technology while leaving technical carnage in its wake. Pay phones booths with the pay phones ripped out and discarded, corded telephones being thrown away, floppy disks and typewriters being recycled because they are no longer the most efficient devices.

During the Academy move to Golden Gate park, staff has helped the internal Greenteam recycle a quarter ton of e-waste at Green Citizen. Green Citizen is a company that recycles computers and e-waste at a small cost so that electronic components don't end up in landfills. What astonished me when sorting through the recycling was that the items that were being recycled were mainly data storage devices. Floppy disks, slides and CDs stacked up by the thousands. Often I don't think about the technology that has seamlessly molded into my life but in this move, I have thought a lot about how that technology has created a great deal of waste. Companies and individuals are now seeking out more responsible ways of recycling but much of it still ends up in landfills.

In the need to keep up with data storage, archives at the Academy have turned from slides to digital scanning, GPS mapping has replaced paper topography, and Skype is keeping researchers in touch rather than phones. It is so important in research to be able to communicate effectively in the remote field areas as well as with colleagues all over the world. Technology is also growing exponentially. In my lifetime alone, I have seen the Internet created, email, cordless phones, mobile phones and GPS. It is an incredible communication age and how we interact is being re-defined but at what cost? Academy policy over the last decade has been to find ways to either donate computers and technology to third world countries or find means to recycle them here. Researchers have seen first hand where electronics and e-waste can end up and what a horrible impact it can have on the bio-diverse environments.

There is a great detriment to faster and expanding communication. While younger generations excel with the technology, older generations are being alienated with technology that seems foreign. As well, the need and demand for better and faster technology creates a pile of obsolete devices and adds to the environmental crisis. This week one comment gave me pause and really made me reconsider if all this technology is a good thing. I don't have an answer but in my concern for the environment – musing over technology this week has made me reconsider if the need for instant communication outweighs its negative waste impact…