The 1995 Blog

1995: The year the future began

Exoplanet discovery a memorable first in 1995

That 1995 was a watershed year is quite clear.

It was the year the Internet and World Wide Web began entering the mainstream. It was the year of the Oklahoma City bombing, the deadliest act of domestic terrorism in U.S. history. It was the year of the O.J. Simpson “Trial of the Century.” It was the year when President Bill Clinton and White House intern Monica Lewinsky began their dalliance, which led to his impeachment.

It also was the year that brought sure proof that planets orbited sun-like stars beyond Earth’s solar system.

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Michel Mayor (Photo: Ann-Marie C. Regan)

As I note in my latest book, 1995: The Year the Future Began, extra-solar planets — or, exoplanets — “had long been theorized, and confirmation that such worlds existed represented an essential if tentative step in the long-odds search for extra-solar intelligent life.”

At a conference in Florence, Italy, on October 6, 1995, two Swiss astrophysicists — Michel Mayor of the University of Geneva and Didier Queloz, a 28-year-old doctoral student — told of the discovery of what soon was confirmed as the first exoplanet.

The exoplanet they found is a large, gaseous, inhospitable world that needs a little more than four Earth days to orbit its host star in Pegasus, the constellation of the winged horse. The planet’s dayside, which always faces the host star — has been estimated to be 400 times brighter than desert dunes on Earth on a midsummer’s day. Its nightside is thought to glow red.

The exoplanet is about 50 light years from Earth and was inelegantly christened “51Pegasi b.”

Mayor reported the discovery at the Ninth Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun, in Florence. About 300 conference-goers were in attendance as Mayor, cordial and low-key, described finding 51 Pegasi b. He and Queloz had used a technique called “radial velocity,” in which a spectrograph measured slight, gravity-induced wobbling of the host star. (The existence of exoplanets is essentially inferred; they are too small and distant to be detected by Earth-based telescopes.)

Mayor’s remarks in Florence were received with polite applause — and by no small measure of skepticism. After all, discoveries of exoplanets had been reported since at least the Nineteenth Century. All had been proved wrong.

Not only that, but a huge planet orbiting so near to its host star posed an unambiguous challenge to the then-dominant theory of planetary formation. It was thought that a giant planet could not long survive the extraordinarily high temperatures and other effects of being so close to its host.

“Most people were skeptical,” Queloz recalled. “The expectation was to find giant planets in long period orbit [that took years, as] in our solar system — we had challenged that paradigm.”

But soon enough, other astronomers — notably Geoffrey Marcy and R. Paul Butler, then of San Francisco State University — verified the discovery of 51 Pegasi b. Marcy, who had developed a reputation for dashing claims of exoplanet discoveries, sent Mayor a congratulatory note that read in part:

“So your wonderful discovery is confirmed!!!”

And the search was on for other distant worlds orbiting sun-like stars.

The quest was soon cast in lyrical terms. “Other worlds are no longer the stuff of dreams and philosophic musings,” wrote John Noble Wilford in the New York Times in 1997.

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NASA illustrations of 51 Pegasi b

“They are out there, beckoning, with the potential to change forever humanity’s perspective on its place in the universe.”

In the 20 years since the conference in Florence heard about the discovery (which was soon after reported in the journal Nature), nearly 1,900 other exoplanets have been detected and confirmed. In addition, NASA’s Kepler space telescope has confirmed more than 1,000 more. Kepler also has detected about 4,700 other candidate-planets.

The Kepler’s most notable recent discovery was what NASA described as “the first near-Earth-size planet in the ‘habitable zone’ around a sun-like star.” In other words, the planet’s size and distance from its star are roughly similar to those of Earth; a “habitable zone” is considered capable of supporting liquid water.

The exoplanet, known as Kepler-452b, was announced in July by NASA, which characterized the discovery as “another milestone in the journey to finding another ‘Earth.'”

Some astronomers suspect the Milky Way galaxy teems with exoplanets, perhaps billions of them. Inevitably, some of them could be an Earth twin, orbiting host stars at distances that would allow temperate conditions, liquid water, and perhaps even the emergence of life as we know it.

All of which represents astonishing growth, and sustained fervor, in exoplanet research since Mayor and Queloz went to the conference in Florence 20 years ago.

Three months before then, they had confirmed the discovery to their satisfaction, in observations at the Observatoire de Haute Provence in France. That, Mayor recalled in an interview in 2011, was akin to “a spiritual moment.”

Mayor, Queloz, and their families celebrated with a bottle of Clairette de Die, a sparkling white wine from the Rhone Valley.

The stunning announcement in Florence caught major news organizations largely unawares, leading to reporting that was muddled, speculative, and downright erroneous. Some of these reports speculated on the implications of the discovery, including the prospect of extraterrestrial life on 51 Pegasi b.

The Guardian news service in Britain, for example, distributed a baffling report that said Mayor and Queloz “may have detected a distant planet that could support life,” adding that it was “the first report of a potential home for extra-terrestrial life.” That hardly could be the case: The proximity of 51 Pegasi b to its host star means the planet’s surface temperature probably exceeds 1,000 degrees Celsius, scarcely conditions for sustaining life as we know it.

Other errors characterized the early coverage. The Washington Post said in its headline on a dispatch from Rome that 51 Pegasi b had been discovered by “Italian Astronomers.” A report on the ABC News program Nightline spoke of two exoplanets, not one, circling the star in Pegasus.

And later in October 1995, the Toronto Star referred to 51 Pegasi b not as a startling breakthrough in space science but dismissively, as “just a celestial slag heap.”


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