The discovery of 51 Pegasi b, the first exoplanet found orbiting a sun-like star, revolutionized our understanding of the universe beyond our solar system.
Why it matters: This groundbreaking finding, announced by Swiss astronomers Michel Mayor and Didier Queloz on October 6, 1995, opened the door to the detection of thousands of exoplanets and challenged our preconceived notions about planetary formation and diversity.
The details:
- 51 Pegasi b is a gas giant with a mass of at least half that of Jupiter, orbiting its star in just over four days at a distance of 1/20th of Earth’s distance from the Sun.
- The planet’s close proximity to its star results in scorching temperatures exceeding 1,000°C (1,830°F).
- Mayor and Queloz used the ELODIE spectrograph at the Observatoire de Haute-Provence in France to detect the star’s wobble caused by the gravitational tug of the unseen planet.
- Confirmation of the discovery came within weeks from a team led by Paul Butler and Geoff Marcy at the University of California, Berkeley.
The discovery of 51 Pegasi b triggered a revolution in the search for exoplanets, with more than 6,000 confirmed to date, each one expanding our knowledge of planetary possibilities and challenging early models of planet formation.
What they’re saying:
- “When the first exoplanet was discovered, I remember thinking that it was really cool, but also thinking, ‘Duh! Of course there are planets out there!'” said Amanda Hendrix, the director of the Planetary Science Institute in Arizona.
- “Trying to use our solar system as the example of what exoplanets should be like led to a big surprise,” said Don Pollacco, lead scientist on the European Space Agency’s forthcoming planet-finding mission and a professor of astronomy at the University of Warwick in England. “The first planets that were discovered were nothing like the planets in our solar system!”
The background: The question of whether other stars host planets has been pondered for millennia, with ancient Greek philosophers like Epicurus and Anaximander speculating on the existence of infinite worlds. However, the first confirmed detection of an exoplanet around a sun-like star did not occur until Mayor and Queloz’s discovery in 1995.
What’s next: As we celebrate three decades since this pivotal moment, astronomers continue to search for exoplanets, driven by curiosity and the relentless pursuit of knowledge about the cosmos, with the ultimate goal of finding an Earth twin.
