Pluto, quasars, and total solar eclipses over Easter Island were just a few of the topics that came up at the close of the first week of the international astronomy conference in Beijing.

Friday was the busiest day of the two weeks my wife and I will spend here in Beijing. I went back and forth between two meeting rooms at least six times in one afternoon, running between presentations that covered everything from solar eclipse maps and historic turns in astronomy to international education and outreach efforts.

Pluto and Quasars at the IAU

Pluto and moons

Just a few months before Pluto was "demoted" from planet status at the 2006 IAU, astronomers Hal Weaver and Alan Stern took this photo using the Hubble Space Telescope, confirming the presence of two fainter moons in the same plane as Charon, Pluto's largest moon.


Hearing how objects are classified in astronomy might sound dull until Pluto comes up. I enjoyed former IAU president Ron Ekers’s inside view of the series of events that culminated in Pluto’s reclassification as a dwarf planet at the 2006 General Assembly. In that controversial meeting, the IAU defined a planet as “a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighborhood around its orbit.”

I found out from Ekers’s talk that individual astronomers (rather than national representatives) cast the 2006 vote. Moreover, I learned that the influence of those interested in dynamic theory (known as the “dynamicists”) was something of an accident, since dynamicists had several IAU sessions in the 2006 General Assembly, but there were no IAU sessions specifically targeted toward planetary geologists, who study surfaces and shapes. That explains why there were few if any planetary geologists in attendance for the 2006 vote, and may explain why the controversial phrase “clears its orbit” was added to the official definition of a planet.

In a subsequent talk, I learned about the continuum of discovery that led up to Maarten Schmidt’s 1962 landmark observation, which confirmed that “quasi-stellar radio sources”—soon shortened to “quasars”—were distant, superluminous beacons that only masqueraded as stars. (As a young Harvard undergraduate, I had attended the 1960 session of the American Astronomical Society meeting, where astronomers reported the optical identification of one of these so-called "radio stars.") We now know that quasars are beams blazing from galactic cores where supermassive black holes gorge on gas and vomit out plasma jets. As astronomer Ken Kellermann (National Radio Astronomy Observatory) explained in his talk, Schmidt’s work represented the culmination of years of hard work by many astronomers, involving the measurement of accurate radio positions, obtaining detailed photographic spectra, and making optical identifications.

Observing Total Solar Eclipses

Total solar eclipse from ground and space

The SOHO spacecraft shows a view of the Sun's outer corona in red, and the SDO spacecraft captures the Sun's face in extreme ultraviolet light. But only during a total solar eclipse can the in-between region be seen from Earth. Jay Pasachoff's team imaged this in-between region from Easter Island in 2010 to trace coronal features from the Sun's surface outward.

Williams College Eclipse Expedition-Jay M. Pasachoff, Muzhou Lu, and Craig Malamut; SOHO's LASCO image courtesy of NASA/ESA; solar disk image from NASA's SDO; compositing by Steele Hill, NASA's Goddard Space Flight Center

After attending the Pluto and quasar talks, I split myself between two rooms, both presenting at and listening to simultaneous meetings of the Solar Division (Division II in IAU parlance) and Commission 46 on Education and Development, of which I’m a past president.

In the Division II meeting I gave my report of the Working Group on Solar Eclipses, describing mapping and imaging studies of the July 2010 total solar eclipse, which was the only total solar eclipse in the most recent triennium. My students and I had observed it from Easter Island, and I showed our series of composite eclipse images, based on individual photographs taken in part by my student Muzhou Lu, who is here with me in Beijing. The images were processed to show the white coronal streamers in detail. Eclipse images from the ground fill in a spatial gap in coronal coverage, which I demonstrated by comparing our ground-based images to those taken by the Belgian's PROBA2 spacecraft, with the SWAP (Sun Watcher with Active Pixels) camera. The combination of visible-light observations from the ground with extreme-ultraviolet images from space broadens our understanding of the corona.

The field of eclipse mapping has been changing, now that “Mr. Eclipse” Fred Espenak has technically retired. (He is still quite active, though, from his home in Arizona rather than from NASA's Goddard Space Flight Center). NASA has ended subsidies for eclipse-map publications. New maps are coming increasingly from cartographer Michael Zeiler and French eclipse enthusiast Xavier Jubier, who makes zoomable Google maps. If you’re curious about the history of eclipse mapping, be sure to read Zeiler’s article in the upcoming November 2012 issue of Sky & Telescope.

Public outreach is especially important for solar eclipses. Looking directly at the Sun can damage your eyes, but even people who know that often do not have access to proper filter material. In 2006 I arranged for a sheet of filter material 1 meter square to be sent to Nigeria, where local students cut it up into smaller squares to observe the eclipse. Local participation made the cost negligible for schools. The forthcoming November eclipse in Australia also raises public awareness issues: the eclipse happens on November 14th local time, but it occurs on November 13th in Universal Time and therefore appears that way in many listings and on maps. It would be a shame for people to fly halfway around the world, only to have bought their tickets for the wrong day.

Many education and development activities are being taken over by the IAU's new Office of Astronomy for Development, which recently opened in Cape Town, South Africa. In the last few years, very successful activities by the Teaching Astronomy for Development program group have brought co-chair Ed Guinan (Villanova University) and his international colleagues to dozens of countries that have little astronomical infrastructure — including Mongolia, Paraguay, and Tajikistan — where they assist professional organizations and institutions with bolstering education and research efforts.

A Bit of Culture

Beijing Planetarium

Jay Pasachoff poses at the Beijing Planetarium with the outgoing and incoming presidents of IAU's Commission on Education and Development, Rosa Ros and Beatriz Garcia.

Jay Pasachoff

These proceedings are not the total sum of the IAU experience. This morning my wife and I went downtown to Beijing Planetarium, a wonderfully large and modern institution. We did not go merely for sightseeing: I was delivering a talk to a group of about 30 local teachers on the history of western astronomy. The day's event was arranged by the officers of the Commission on Education and Development, outgoing president Rosa Ros from Spain and incoming vice-president Beatriz Garcia from Argentina, as part of the NASE (Network for Astronomy School Education). Someone from the Shanghai Observatory translated as I spoke, tracing the development from Aristotle to Ptolemy to Copernicus to Tycho Brahe to Kepler to Galileo and finally to Newton. I also included some information about the thousand-year-old Dunhuang star map from western China, which is now in the British Museum — and I was surprised to discover that none of the local teachers knew about the map. I was there to share with them my heritage, and inadvertently taught them about their own.

Jay Pasachoff and Jocelyn Bell

Jay Pasachoff stands with Jocelyn Bell Burnell, the discoverer of pulsars. She delighted her audience by reciting the names of the 75 speakers and 75 poster participants in rhyming verse.

Jay Pasachoff

Culture continued to intrude into the meeting itself, too. In her summary lecture for the symposium on modern pulsar studies, Jocelyn Bell Burnell (Open University, England) surprised and delighted the audience by reciting the names of the 75 speakers and 75 poster participants in rhyming verse. (She had previously edited a book of poetry on astronomical themes.) Bell Burnell discovered the first pulsar as a young graduate student in 1968. That one set of fuzz that she spotted on an unrolled strip chart of radio observations was soon followed by three more, ultimately leading to the huge group of talented scientists who have just spent these past five days presenting observations that literally span the entire radiation spectrum and discussing our current ideas for how these rapidly spinning dead stellar cores emit their radiation.

On Saturday, Naomi and I headed six hours north to the Chinese autonomous region of Inner Mongolia. I'll share what we saw in my next post, stay tuned!

Read more about Jay's adventures at the IAU:


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