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Finding footprints on Jupiter.
In earth’s night sky, bright curtains of colored light, called aurora, are sometimes visible in the far northern and southern latitudes. These beautiful light shows result from electromagnetic storms generated when the solar wind — powerful, high-speed streams of atoms and electrons emitted from the sun — hits the magnetosphere, a region of space around earth rich in charged particles that flow in streams directed by earth’s magnetic field. The aurora on earth fluctuates, depending upon conditions on the sun, and the vast energies involved can seriously affect life on earth. “Space weather,” the study of this sun-earth connection, has evolved into an important field in today’s era of large regional power grids, wireless technology, and communication satellites.

The interests of John T. Clarke, a CAS professor of astronomy and faculty member in the Center for Space Physics, however, lie further afield. Clarke studies auroras on the faraway planets Jupiter and Saturn. Recently he and his colleagues used the Hubble Space Telescope Imaging Spectrograph to produce brilliant ultraviolet (uv) images showing auroras on the planet Jupiter. By imaging in the uv the researchers were able to differentiate between the auroras and reflected sunlight, revealing auroral footprints on the outer atmosphere of Jupiter created by the enormous electromagnetic forces generated between the rapidly spinning planet and three of its largest moons, Io, Ganymede, and Europa. Combining the Hubble observations with data from the orbiting Cassini and Galileo space missions, the researchers were further able to map the footprints of Jupiter’s auroras over time. To an observer looking up, these “footprint” auroras would appear very bright, as bright as clouds reflecting the lights from Boston. They would not fill the whole sky, but would move from one horizon to the other (from east to west) in just a few minutes.

Although Jupiter’s constant and ongoing auroras are very different from earth’s, Clarke believes that understanding the dynamics of Jupiter’s auroras may lead to a better understanding of earth’s space weather. Also, according to Clarke, the technique of imaging auroras in the uv is a useful tool that holds great promise in the search for evidence of massive planets orbiting close to nearby stars, planets that may otherwise be masked by the brightness of their stars.

In the meantime, as the Cassini mission heads toward Saturn, with a projected arrival in July 2004, Clarke is preparing to gather more information about auroras on yet another planet in our solar system.
Clarke’s research is the cover story in the February 28 issue of the journal Nature, which focuses on recent research about the planet Jupiter obtained when Cassini flew past Jupiter last winter.

The Ice Cream Road.
Unlike the Silk Road, which traces the direct path traveled by ancient traders transporting silk from Asia to Europe, the Ice Cream Road takes off in disparate directions, bringing vanilla, chocolate, and strawberry to a multitude of cultures around the globe. “Ice cream is not a fixed recipe,” says Merry White, a CAS anthropology professor and an expert in the cultures of China and Japan. “It’s a technique rather than a dish, and travels easily, taking on new flavors as it goes.”

White’s study of “global gelati” has taken her to Shanghai, where Ven-Ice, a trendy gelato shop, now shares space with other high-end consumer stores in the building that housed the First Communist Congress in China. In Japan, she notes, young women rush out to buy gifts of chocolate ice cream
for their boyfriends and bosses on Valentine’s Day. The favor is returned a month later, when the gentlemen present the women with vanilla ice cream. Ice cream fills a number of needs within a culture, says White — among them nostalgia, indulgence, and adventure.

But adventure notwithstanding, vanilla, chocolate, and strawberry are the most popular flavors worldwide. Such seemingly Asian flavors as ginger, green tea, and adzuki bean were first promoted in America to please palates used to a sweet dessert after a meal in a Chinese or Japanese restaurant. When these flavors began to show up in the ice cream shops of Asia they were considered “exotic” alternatives to the traditional trio of ice creams. “We assumed that flavors would be localized, that they would have to be on the spectrum of flavors popular in a country,” White says. “But, it turns out that culture does not bind people to flavors.”

White presented her findings at the annual meeting of the American Association for the Advancement of Science, held in Boston in February.

"Research Briefs" is written by Joan Schwartz in the Office of the Provost. To read more about BU research, visit http://www.bu.edu/research.

8 March 2002
Boston University
Office of University Relations