Physics, Earth & Space Icon Physics, Earth & Space

Solar Eclipses Still Inspire Science


The film and book The Privileged Planet introduced a class of phenomena about the earth that show a curious linkage between the requirements for habitability and opportunities for scientific discovery. The first example involved total solar eclipses. The close match between the sun and moon’s apparent diameters that permit total eclipses also have allowed scientists to discover helium, learn the chemical composition of the sun, and confirm Einstein’s theory of relativity.

Materialists must believe this linkage is mere coincidence. For example, Tom Metcalfe titles his Live Science article, “Why Total Eclipses Are Total Coincidences.” Nowhere does Metcalfe specifically dismiss the Privileged Planet hypothesis, but he seems to work overtime to pre-empt design by repetition, using the word coincidence nine times, occasionally with strong adjectives for emphasis: sheer coincidence, total coincidence, celestial coincidence. If we add accident of geometry, that’s ten.

“It’s a beautiful coincidence — life has been on Earth for about 400 million years, and we’re living in this little window of time where this is happening, which is pretty amazing,” [Mark] Gallaway told Live Science. [Emphasis added.]

One of Metcalfe’s arguments for sheer dumb luck is that scientific discoveries made during eclipses are old news. Calling on Mark Gallaway, a U.K. astronomer, for support, he says:

Although some solar eclipses have played an important role in science, such as the 1919 eclipse that helped verify Einstein’s theory of general relativity, these celestial events don’t always hold much scientific interest today, he said.

“Eclipses are one of the most well-examined things in science. We know how they work, and to be honest, we’re just going out there because we like to see eclipses,” Gallaway said.

Metcalfe allows for a couple of little mysteries that remain to be studied, but relegates the big discoveries to long-past historical anecdotes. Is this correct? Are today’s total eclipses just lucky breaks for our entertainment? Is the Privileged Planet argument outdated? The news about the upcoming August 21 eclipse shows otherwise.

An indication of the ongoing scientific value of eclipses can be seen in NASA’s attempt to recruit thousands of “citizen scientists” in the event. The Great American Eclipse will likely be the most-studied total solar eclipse in history. Some 12 million viewers live within the path of totality, and over half the U.S. population lives within 400 miles of the path, according to Having so many observers makes this eclipse a bonanza for scientific observation, and NASA is taking advantage of it with a special website giving people instructions for how they can get involved. Here are just three of the six research projects planned:

  • GLOBE Observer: What happens in the atmosphere and on Earth’s surface when the Sun’s light is blocked, even temporarily?
  • Ham/Sci: This project by Virginia Tech and New Jersey Institute of Technology will employ amateur radio enthusiasts to study the ionosphere during the eclipse.
  • Life Responds (California Academy of Sciences): Many have reported unusual changes in animal behavior during eclipses. This project “will make scientifically-valuable observations of many aspects of this behavior.”

One project involving the public is NASA’s “Eclipse Ballooning Project.” An infographic shows how students at universities and high schools, from Oregon to South Carolina, will participate in launching 57 high-altitude balloons that will rise 100,000 before, during and after the eclipse. The balloons, to be monitored by the Iridium and GPS satellites for location, are equipped to collect multi-spectrum data and transmit it to earth, where it will be live-streamed to scientists and to anyone with Internet access.

Farther up, astronauts on the International Space Station will be able to witness the eclipse three times from orbit. NASA’s eclipse website shows the orbital path. The astronauts will beam down what they see from their high platform. Their vantage point also allows them to monitor the shadow of the moon on the ground.

The NASA eclipse site also lists numerous research projects it is undertaking in “Science from the Ground.” Research teams will take advantage of the eclipse to study the solar corona, the earth’s atmosphere, earth’s outgoing radiation, and more. Here’s a taste of the valuable science that can only be studied during an eclipse:

During the eclipse, a team of scientists led by Paul Bryans at the National Corporation for Atmospheric Research will sit inside a trailer in Camp Wyoba atop Casper Mountain in Wyoming, and point a specialized instrument at the sun. The instrument is a spectrometer, which collects light from the sun and separates each wavelength of light, measuring their intensity. This particular spectrometer, called the NCAR Airborne Interferometer, will for the first time survey infrared light emitted by the sun’s atmosphere, or corona. Such an experiment can only be conducted from the ground during an eclipse, when the sun’s bright face is blocked, revealing the much fainter corona.

This novel data will help scientists characterize the corona’s complex magnetic field — crucial information for understanding and eventually helping forecast space weather events. The scientists will augment their study by analyzing their results alongside corresponding space-based observations from other instruments aboard NASA’s Solar Dynamics Observatory and the joint NASA/JAXA Hinode.

NASA lists nine smartphone apps the public can download to learn about the eclipse. created another app of its own. Search for “eclipse” in your iPhone or Android app store and you will get dozens of hits.

In addition to NASA, universities are planning eclipse research projects, some recruiting citizen scientists. Here’s an interesting one at the National Solar Observatory, learning something brand new for 2017:

Citizen/CATE (National Solar Observatory): The Citizen Continental-America Telescopic Eclipse (CATE) Experiment will use more than 60 identical telescopes equipped with digital cameras positioned from Oregon to South Carolina to image the solar corona. The project will then splice these images together to show the corona during a 90-minute period, revealing for the first time the plasma dynamics of the inner solar corona.

See also this article from the Seattle Times about CATE. Sandi Doughton features some of the participants in the project, beginning with a story of a father-and-son team from Corvallis stationed atop a peak in the coast range, describing how pumped they are to do well.

A group of scientists will board two WB-57F jets during the eclipse, specially outfitted with high-tech telescopes, to image the corona at much higher resolution than possible from the ground, according to During the observations, they also plan to learn about the soil of the planet Mercury, because that planet is difficult to observe except during an eclipse. Here is another research opportunity made possible only during a solar eclipse:

The researchers could also potentially search for vulcanoids — a family of hypothetical asteroids that may lie between Mercury and the sun. The total solar eclipse also provides the perfect opportunity to search for vulcanoids, which are believed to be remnants of the early solar system. Vulcanoids have likely evaded detection due to their small size and the unforgiving glare of the sun. During the eclipse, however, the sun’s bright light will disappear, allowing scientists to look for these elusive objects.

A team in Boulder, Colorado will use a special radiometer to learn more about earth’s energy system, to provide better data for climate models ( This article lists a variety of other research projects taking advantage of the eclipse.

The American Astronomical Society’s Eclipse Task Force is going to use the occasion to figure out how big the sun is. That’s right; the size of our own star is not known as precisely as that of the earth and moon, Sarah Levin reports in Live Science. “The 2017 Solar Eclipse May Prove the Sun Is Bigger Than We Think,” her surprising headline announces.

In summary, the National Science Foundation says that the 2017 eclipse “offers unique research opportunities” — emphasis on unique. Let this quote respond to Metcalfe’s dismissive claim that scientific research during total eclipses is old news:

“This total solar eclipse across the United States is a unique opportunity in modern times, enabling the entire country to be engaged through modern technology and social media,” said Carrie Black, a program director in NSF’s Division of Atmospheric and Geospace Sciences. “Images and data from as many as millions of people will be collected and analyzed by scientists for years to come.

This is a generational event,” agreed Madhulika Guhathakurta, NASA lead scientist for the 2017 Eclipse. “This is going to be the most documented, the most appreciated, eclipse ever.

We’ve just seen a few of the research opportunities in stellar physics, planetary geophysics, atmospheric science, geomagnetic science, climate science, plasma physics, ecology, animal behavior, space weather, and more — all made possible by the unique “coincidence” of total solar eclipses. The geometry of a total eclipse is also tightly linked to the requirements for habitability, as Privileged Planet argues, because we have to orbit the right kind of star, at the right distance from the star, with a moon as large as our moon, to exist.

Because these requirements are met here, earth is habitable, and simultaneously meets the requirements for solar eclipses. And since earth is inhabited by sentient beings (not necessarily a logical consequence of habitability alone), we can appreciate solar eclipses and use them to study the nature of everything from plants and animals to the far reaches of the cosmos. “The same narrow circumstances that allow us to exist,” according to the Privileged Planet hypothesis, “also provide us with the best overall setting for making scientific discoveries.”

If eclipses provided the only linkage between habitability and scientific observation, one might allow for the conclusion that they are coincidental. But the authors amass an impressive list of other coincidences, from the solar system to our galaxy to the properties of physics, that all point in the same direction, suggesting “conspiracy” rather than coincidence. That is why co-author Jay Richards begged to differ with the “coincidence” view of all these fortuitous linkages. In The Privileged Planet film, he concludes:

Our argument suggests something completely different. It suggests that the universe was intended, that the universe exists for a purpose, and that purpose isn’t simply for beings like us to exist, but for us to extend ourselves beyond our small and parochial home: to view the universe at large, to discover the universe, and to consider whether, perhaps, that universe points beyond itself.

Photo: Total eclipse, photographed from Neem Ka Thana, Indian, 1995.