Interview with Bill Nye: The Sundial Guy

Bill Nye, the Sundial Guy

The first interplanetary sundial is expected to make it to Mars on Jan. 4, 2004.

Identical sundials, each about 3 inches square, are being carried by the two Mars Exploration Rovers, the first of which was launched from Cape Canaveral Air Force Station on June 10. The second rover launched one month later, on July 7. Both carry a suite of scientific instruments called the Athena package, and one very ancient timekeeper, a pair of sundials, which in addition to tracking the sun on the mobile rovers, will also allow photographic calibration of colors as they are displayed on all the martian images returned digitally to earth.

Each sundial is inscribed with the words "Two Worlds, One Sun" and bears the name "Mars" in 17 languages, including Bengali, Inuktituk, Lingala and Malay-Indonesian, as well as ancient Sumerian and Mayan. Four gold panels along the sides of the sundials are inscribed with stick-figure drawings of people [called 'sticksters'], as well as a message to future Mars explorers.

Behind the idea for the martian sundial is the Cornell graduate and educator Bill Nye, whose contagious passion for science made him a television star. Nye is equally enthusiastic about the forthcoming martian missions. Nye said: "I’m very proud of the sundial, and I’m honored to be part of the team."

Astrobiology Magazine had the opportunity to interview Nye about his forthcoming contribution to science and education on the twin martian probes.


Astrobiology Magazine (AM): What triggered your first inspiration to suggest sending the sundials to Mars?

Bill Nye (Nye): Jim Bell, the Cornell astronomy professor in charge of the Panoramic Camera (pancam), approached me on a flight to Ithaca, NY. He asked me if I’d like to attend a meeting about the Mars Exploration Rovers, which were on the drawing boards in the early winter of 2000. I was thrilled.

In an earlier version of the sundial, the gnomon was gold, but the bright color interfered with callibration
Credit: NASA/JPL/Cornell

I attended the meeting in the Space Sciences building, where Carl Sagan had worked. I took one look at the "photometric calibration target," and exclaimed or quickly proposed with a weird urgency, "That’s got to be a sundial," or something like that.

My dad was fascinated with sundials. He photographed hundreds of them and wrote a book about them. He designed a Nye family dial that kept time at our house in Washington, DC.

Sundial enthusiasts (gnomonicists) reach a point, where every shadow-casting thing you see should perhaps be converted into a sundial. This would include telephone poles, loosened nail heads on wooden decks, picnic sandwich toothpicks, birdfeeder posts, and the Washington Monument. The shadow-casting post on the calibration target was an obvious opportunity for proselytizing, perhaps enriching the lives of Mars scientists.

AM: You began designing the sundial for the 2001 Surveyor Lander, which was cancelled, correct?. Any differences between that original design and what is flying on both exploration rovers now, other than the change of the sundial’s gnomon from gold to black?

Nye: I guess the work was originally for the 2001 Surveyor. I am pretty sure it got "re-scoped" to become the Mars Exploration rovers. The time-reckoning portion of the design for the Rover dials did not change much after Woody Sullivan got on it. One of the fundamental features of these dials is that they have no hour lines. They can’t, because the platform they’re mounted on will move often.

When sundials are near the equator of a planet, you don’t want a triangular shaped gnomon (shadow-caster). You want a rectangle or simply a post. These two things I was able to point out right away in that meeting. For the next level of detail, I said, the guy for this is Woody Sullivan. Everybody felt that these features and getting Woody involved made the dials even a little more intriguing.

But to address your question a bit more, it might depend what you mean by "design." The writing had to be changed to read "2004," which necessitated a plate being bonded over the original engraving. The gnomon was originally black. But as you mention, the top hemisphere of the upper nodus, or ball, was gold as was the lower nodus, or star. These are, in an art designer’s view, design changes, I suppose.

After testing, we found some "glints" or "glinting," so the gnomon had to be painted with that eerily flat, black paint. It’s so non-reflective; (How non-reflective is it?); it’s so non-reflective that it looks like it’s not there, or that it’s some sort of odd cut-out in a few of the close-ups of the dial.

AM: Any differences needed because of the different landing sites for the twin rovers? Presuming that both sundials are identical?

Nye: Both dials are the same. Since the hour lines are going on long after the shadows are cast (say 11 minutes or so), and since they’re both landing near the equator, they can be exactly the same.

Bill Nye demonstrates the day(left) and night views of the Mars sundials, as the position changes over a typical "Sol", or martian day.

Making science entertaining and accessible is something that Nye has been doing for most of his life. Humor runs rampant in his family – "we get together and just laugh for hours" – and his parents made sure he knew the value of education. Nye discovered he had a talent for tutoring in high school, and while growing up in Washington, DC, he spent his summers demystifying math and science for fellow students. When he wasn’t hitting the books, he was hitting the road on his bicycle, which he spent hours taking apart and rebuilding, to "see how it worked." Nye’s fascination with how things work led him to Cornell University and a degree in mechanical engineering. After graduation, he headed for Seattle to work as an engineer at Boeing. "I’ve always loved airplanes and flight," says Nye. "The space program was really important to me as a kid. I still have a photo of Armstrong and Aldrin on the moon in my living room."

It was in Seattle that Nye began to combine his love of science with his flare for comedy, when he won a Steve Martin look-alike contest and developed dual careers as an engineer by day and a stand-up comic by night. Eventually, he segued into a fortuitous combination of both science and comedy as Bill Nye the Science Guy, performing and writing on KING-TV’s late night ensemble comedy show, "Almost Live" (on Comedy Central), guesting on The Disney Channel’s "Mickey Mouse Club" and "Late Night with David Letterman" and answering science-related questions on local and national radio programs.With fellow KING-TV alumni, Jim McKenna and Erren Gottlieb, Nye has also made a number of award-winning educational videos and programs for school-age children and adult audiences, among them "Fabulous Wetlands" for the Washington State Department of Ecology. Along with his duties as head-writer of "Bill Nye," he has also written "The Science Guy’s Big Blast of Science," an introductory science text, and will be featured in forthcoming episodes of "Eyes of Nye" television shows.

As a signature example of terrestrial life on our pale blue planet, another important piece of human culture is represented on the sundial: baseball, since both Nye and sundial expert, Woody Sullivan are fans. To save weight, six holes in the shape of home plate were cut out of the underside of the aluminum base.
Photo Credit: Cornell; Caption Credit: Wm. Morris Agency

The positions of the Earth and Mars were designed for earlier launch dates, which were postponed after the Polar Lander aand Climate Orbiter failures. The dial faces are made with fancy silicone rubber dots that represent the Earth and Mars. They’re embedded in circles (annuli) that represent the orbits of the planets made of the same sort of material.

The reflectance of these features is precisely known. To move the Earth and Mars rubber dots would have required recasting, reradiating, and recalibrating, so we left them were they were. That is, where they are– perhaps a little mystery for the Martian archeologists that may one day visit there.

AM: Because the rovers are moving around in orientation all the time, you are going to superimpose an electronic hour mark on top of the sundial, which adjusts for the rover’s orientation to the sun? Will this time have to be adjusted for the 11 minute transit time to get the images back to Earth?

Nye: Yes to the first question, "sort of" to the second. We will superimpose a full complement of hour lines each time we get a good view sent back. There are no conventional hour lines at all on these dials. Because unlike regular sundials, they are on moving platforms.

One of the charming challenges is roughly, "What is an hour on Mars?" Is it a "Mour?" Is it a "quadraduodeci-sol," a twenty fourth of a sol, a Mars day? Why a 24th, for example?

Right now, we’re planning Earth time, marking the hours electronically, changing them roughly continuously.

When we see the shadow on our images, are we seeing the time eleven minutes ago on Mars? Or are we seeing the time on Mars as observed from Earth now? It’s like time travel problems in science fiction. When is now; when was then?

With information and events moving through the cosmos at the speed of light, can we say that events are happening on Mars, or do we have to say those events don’t happen here for eleven extra minutes? Hmmm.

Bear in mind also that the eleven minutes is approximate, and it’s always changing. Right now, I imagine we’ll post the local solar times on Mars with the shadow images. Since there may be other lost time in signal processing and especially in getting the images posted, the delay will be reported or placarded rather than accounted for in the hour line positions.

Mars from the Viking 1 Lander
The first color image transmitted to Earth from the Viking 1 lander, with its saturated red color and orange-pink sky. The lander went about its business collecting 4,500 images for more than six years, from July 20, 1976 until November 1982, substantially exceeding its design lifetime of 90 days.
Credit: NASA

Earth bound sundials, the only ones that humans have set in place so far, measure solar time. The duration of daylight varies every day. So, in sundialing we think of solar time and clock time. We somewhat arbitrarily, albeit logically, divide the Earth’s solar year up into 31,556,926 seconds with clocks.

In ancient times, the day was divided only by the shadows, solar time.

AM: What happens if the sun is not apparent, from dust or clouds? For instance, there is one entire day devoted to sundial observation. Has that day been set for both rovers yet–or is that changing depending on what happens on the surface?

Nye: If it’s dusty out, we won’t do the sundial observation time-lapse that day. But, the photometric calibration targets are still useful on dusty days. They have color patches and reflective surfaces, and so on. If the shadow is washed out by diffused light, well, the useful effects of pink or orange shadows have to be inferred and approximated without observation. As far as I know the science-powers-that-be will pick the all-day dial observation time after we have gathered and secured an acceptable number of other images and data. Those data can be analyzed, while more pictures are taken that include the dials. This is as far as I know.

AM: How long are the panoramic cameras slated to be available? During the daytime for the full 90-day primary mission, say from January to April 2004?

Nye: As far as I know, the pan-cams are to be run every day or sol. The useful time for the missions and the cameras is probably going to depend on how much dust settles on the solar panels. It’s an odd or surprising constraint. But that’s it, if nothing else goes wrong.

We may be able to fire the space crafts back up during the next Martian summer. We’ll see, perhaps literally.

AM: How will the cameras use the colors on the sundial to adjust brightness and color? Basically, these will subtract off the dominant pink color seen on the surface, based on the known colors on the dial to calibrate for ‘over-pinking’?

Nye: The colors of the color "coupons" are very well known or calibrated. And, so is the brightness of each of the white, gray, and nearly black circles (annuli). So, we adjust the images so that the colors and brightness come out right, the way we know them to be from our calibrations back here on Earth.

The orange and pink business comes from the following charming feature of shadows. Try this: Get a very white piece of paper, and go outside in the sun. Make a shadow on the paper with, say, a pencil, or your finger. Look carefully at the shadow. It’s not black, not really black at all. It’s gray, but it’s also light blue. Scattered sky light fills in behind your shadow-caster. The same thing happens on Mars. Only there, the light is pink or orange. So, to get closer to true colors, we have to subtract the sometimes very strong effect of dust in the Martian sky, which adds a lot of pink light. I say pink. Some people would say it’s closer to orange. Well, that’s why we have the calibrated coupons. One guy’s orange is another guy’s pink. But 620 nanometers is the same for all of us.

Before people figured this out back in the first era of Mars probes (also the first Disco Era) the images from the Viking spacecraft were too pink or orange. Those "over-pink" images still show up in Mars science fiction movies and Mars-themed posters and restaurant walls.

AM: What is the history behind selecting what was inscribed on the sundials? The "Two Worlds, One Sun" motto in 17 languages, and so forth?

Nye: As a student of Carl Sagan’s, a Planetary Society Board Member, I came of age during the Voyager missions. I was in the lecture on during the days, when Professor Sagan asked the class which songs we thought were worthy of being sent out of our Solar System, messages in bottles to be cast into the Cosmic Ocean. These were whimsical in a sense, almost silly, self-delusional perhaps. The chance that they will ever be found is almost unimaginably remote. But, it is also a notion that fills us with wonder and hope. The idea is irresistible– a message from humankind for all time.

Carl Sagan described the Plaques that were affixed to the side of the spacecraft. These were to be sent where no one has gone before for roughly eternity. That made quite an impression on me as a student.

So, when this came up, I immediately suggested an inscription on the one place, where I believed there would be space available, the edge of the aluminum photometric calibration target, the sundial. I wrote the copy and sent it to the Mars team members I knew.

Everyone liked the idea. People made a few suggestions. Steve Squyres [Cornell project scientist on the Mars Athena science] liked it very much and made it better.

Now, two of these inscriptions are on their way to Mars. It gives me chills. I feel as though I contributed to something big and worthy of the best of humankind–exploration:

"People launched this spacecraft from Earth in our year 2003. It arrived on Mars in 2004. We built its instruments to study the martian environment and to look for signs of water and life. We used this post and these patterns to adjust our cameras and as a sundial to reckon the passage of time. The drawings and words represent the people of Earth. We sent this craft in peace to learn about Mars’ past and about our future. To those who visit here, we wish a safe journey and the joy of discovery."

Woody Sullivan, who is one serious gnomonicist, pointed out, or maybe insisted that sundials should have a motto. We mulled a few of the traditional ones over: "I only count the sunny hours," "Tempus fugit," or "Time Flies."

Carl Sagan
The National Academy of Sciences awarded Sagan the 1994 Public Welfare Medal for "communicating the wonder and importance of science."

Woody knows of a dial in France that says, "Every hour injures; the last one kills." Wow.

Anyway, I was having dinner with Lou Friedman and Bruce Murray. We’re all part of the Planetary Society, the organization those guys started with Carl Sagan. We got to talking about the dial, and Lou came up with "One Sun; Two Worlds". In a few moments, we agreed that it should be "Two Worlds; One Sun". We also agreed that that we were onto something. Sure enough, everyone embraced it. I guess I’ll never forget it.

Lou and Bruce got Jon Lomberg involved, the guy who did the artwork on Sagan’s landmark "Cosmos" series. He, along with some thoughtful school kids, created the artwork along the edges. They’re stick figures that I like to call the "sticksters."

They give the instrument a little whimsy, and they are, to me, so human. How different are engravings in hardened aluminum catching Martian sun from petroglyphs laboriously scraped into south-facing rocks on Earth aligned with the sunrise? People made them.

AM: How do you personally feel about contributing this kind of permanent ‘message in a bottle’ to the future?

Nye: It’s a thrill I may never match. I am honored to have been included and given a chance to contribute to space exploration.

AM: A big part of the Apollo 12 mission was recovering a piece of a lunar surveyor lander and bringing it back to Earth. This profile was to demonstrate precise lunar landing and also to see for effects of weathering and aging on the lunar surface. What do you think about future Mars landings having something to do with bringing back the sundials, for some of the same reasons? Would that be an intriguing outcome to your team’s unique story?

an artist's rendition of a
The next generation: an artist’s rendition of a Mars Exploration Rover, due to land on the Red Planet in January 2004.
Credit: NASA

Nye: I guess it would be intriguing, but I hope nobody feels like they have to take these things apart and haul them back. In a hopeful view of the future, I can imagine the landing sites becoming part of Martian history.

The Martian residents in the distant future could go on occasional outings to see the old Rovers and hear the story of the sundials, and check their time pieces against the dials which, I am pretty confident will still be reckoning the passage of Martian time.

In a less ambitious view of the future, people might go to the rovers and take them apart for analysis, because they need to know what happens to the material over that much time, because they’re engaged in the developing new weapons or new ways to cope with an uncomfortably changing environment back on Earth. Or perhaps they’ll just tear them apart to see what’s inside without any sense of history or need to preserve them.

For now, I hope there will someday be future visitors, who can admire them as calibration instruments and as sundials.

An astonishing part of the story concerning the recovery of parts from the Surveyor spacecraft is that there were microbes on the spacecraft that had accidentally been left on board, and they successfully stowed-away. They survived for years in the harsh environment of the Moon. When they got back to Earth, they continued to grow. It’s compelling evidence for astrobiologists that the environmental limits for living things are set pretty far apart. [Ed. note: see debate on this issue from Surveyor's project scientist, Leonard Jaffe].

I hope these Mars Exploration Rover spacecraft are sterile.

I leave it to future explorers to decide their fate.

AM: Any future plans for including sundials as a general calibration in the future, since that is likely part of any imaging project in space exploration?

Nye: I sure hope so.

Sundials are so much a part of human history. Eratosthenes inferred the diameter of the Earth within perhaps 4% using the shadows of sticks.

Our world is driven by our remarkable ability to carefully measure and divide units of time. In a reasonable sense, the invention of clocks has had a greater effect on our lives than the invention of wheels. You can invent wheels relatively easily, if you live where trees fall over.

Clocks are hard to come up with. Our clocks still run clock-wise, because the first sundial shadows ran clockwise. We’ve probably only begun to exploit what information and inspiration we might get from shadows in the sun.

What’s Next

Orbital projections of where the Mars Exploration Rovers are right now, can be continuously monitored over their half-year journeys, which culminate in their landing around January 2004.


Collaborators on the Mars Sundial project include:

* Bill Nye, a 1977 Cornell engineering graduate, Rhodes Class of ’56 Professor and host of the PBS show, "Bill Nye the Science Guy", and the upcoming "Eyes of Nye" television shows
* Steven Squyres, Cornell professor of astronomy and principal investigator for the Athena suite of science instruments carried by the rovers;
* Jim Bell, Cornell assistant professor of astronomy and lead researcher for the high-resolution stereo Pancams carried by both rovers;
* Woodruff "Woody" Sullivan, sundial enthusiast and professor of astronomy at the University of Washington;
* Tyler Nordgren, Cornell Ph.D. ’97, an artist and astronomer at the University of Redlands in California;
* Jon Lomberg, an artist and creative consultant to the Mauna Kea Center for Astronomy Education, University of Hawaii at Hilo;
* Louis Friedman, executive director of the Planetary Society.

JPL, a division of the California Institute of Technology, manages the Mars Exploration Rover project for NASA’s Office of Space Science, Washington, D.C. Additional information about the project is available from JPL and from Cornell University, Ithaca, N.Y

Related Web Pages

Cornell sundial page
Where is Spirit Now?
Athena Science: Cornell University
Five Year Retrospective: Mars Pathfinder
Sundial Links