MARK GARLICK

The technology was a complete joy, says Andrea Ghez, thinking back to the mid-1980s and her first time helping out at an observatory. She wanted to learn everything. How to open the dome! How to fill the instrument with liquid nitrogen! Develop the plates! Reduce the data! Coding!

And then there was the science. Ghez did not know much at the start; she was majoring in physics at the Massachusetts Institute of Technology (MIT) in Cambridge, working for an astronomer as her undergraduate research experience. But as she learned more about his research into unusual cosmic sources of X-rays, Ghez became enthralled by the thought that some of those sources might be black holes singular points with a gravitational pull so strong that not even light can escape them. It got me completely fascinated by black holes, she says. By the time she had spent two undergraduate summers working at telescopes in Arizona and Chile, Ghez was hooked. I fell in love with the whole profession.

Now an astronomer at the University of California, Los Angeles, she still feels the same. Her fascination with black holes has led her into a pioneering, decades-long study that has proved the existence of the biggest black hole in our cosmic neighbourhood: the 4.1-million-solar-mass behemoth that lies at the centre of the Milky Way1, 2 (see 'The monster in the middle'). This work earned her a MacArthur 'genius' award in 2008, and half of the Crafoord prize, astronomy's Nobel, in 2012.

Ghez's love of technology helps to explain why her quest has been so fruitful. Most astronomers use only the tools they know, but Ghez is an enthusiastic early adopter first in line to try out cutting-edge detectors and optical techniques that are barely out of the laboratory. I like the risk of a new technology, she says. Maybe it won't work. But maybe it will open a fresh window on the Universe, answering questions you didn't even know to ask, she says. Any time you look, you're astounded!

Reinhard Genzel, a director of the Max Planck Institute for Extraterrestrial Physics in Garching, Germany the co-winner of the 2012 Crafoord prize and Ghez's sharpest competitor on the Galactic Centre work puts it very simply. Andrea, he says, is one of a rare adventurous class.

Ghez's devotion to her work would make her seem fierce if she weren't always smiling, and her sentences didn't keep exploding into verbal capitals. As it is, with her barely controlled curls, straight-across eyebrows and direct gaze, she conveys a cheerful intensity. She doesn't digress when she talks; she focuses. And she has always had a certain determination.

According to Ghez family legend, when 4-year-old Andrea watched the first Apollo Moon landing with her parents in Chicago, Illinois, on 20 July 1969, she announced that she, too, was going to the Moon as an astronaut. True, she also wanted to be a ballerina. But while attending the progressive University of Chicago Laboratory Schools, she says, she became really clear that she loved mathematics and science. That passion took her to MIT in 1983 and then, after her epiphany in the observatory domes, to the California Institute of Technology (Caltech) in Pasadena for graduate studies in astronomy.

Caltech, Ghez explains, had the best toys by far. Among them was the 5-metre Hale Telescope, then one of the world's largest, on California's Palomar Mountain. But the toy that particularly captured Ghez's interest was an experimental speckle imager, an instrument intended to get around astronomers' eternal problem with air. Earth's atmosphere is transparent but turbulent a collection of bubbling 'cells' that are warmer here, cooler there, and constantly moving. Looking at the sky through all that is like looking at pebbles on the bottom of a rippling stream: the light coming into the telescope flickers, dances and fragments, smearing the point-like image of each star into a fuzzy ball.

Speckle imaging freezes the dancing images in place with a camera that captures very short exposures every few milliseconds, taking maybe 10,000 or more shots in total. The result is a sequence of very faint images in which the distorted light from each star produces a scattering of spots: the speckles. Computer processing recombines the speckles into one spot per star. Then all the exposures can be aligned and stacked to produce a final image with the worst of the atmospheric smearing removed.

Read more:

Astronomy : Star tracker