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Is it a planet, or isn't it? Scientists disagree
February 26, 1997
Web posted at: 10:22 p.m. EST (0322 GMT)In this story:
From Correspondent Greg Lefevre
SAN FRANCISCO (CNN) -- Is science in such a hurry to find life on other planets that it mistakes a quivering star for evidence of another Earth?
Astrophysicist David Gray thinks so. In a paper published in the journal Nature, Gray rebuts recent claims of planets discovered out there in the stars.
"The planet simply cannot explain the new observations at all, period," Gray said.
The University of Western Ontario scholar disputes last year's discoveries by astrophysicists from Cornell University and the University of California of planets in a distant solar system.
The original theory works this way: scientists look for a slight wobble in the light patterns of a distant star. They deduce that wobble is caused by the tiny tug of a planet orbiting around the star every four days.
But Gray says it's not a wobble at all.
"The changes are actually coming from the star itself, and not from the planet tugging the central star around," Gray said.
The issue: how does a star pulse?
The star pulses light as it expands, contracts and rotates, perhaps showing a side that is brighter or dimmer, he said, "like a sunspot, or a storm, like the red spot on Jupiter kind of thing. Or if you've got a bright spot or a dark spot."
It becomes all the more important because the star being studied, called 51 Pegasi, is a lot like our sun. That means any planets orbiting it could be a lot like our Earth.
The debate is on. Geoff Marcy, one of the original scientists who says there's a planet out there, disputes Gray's pulsation theory. He says stars like our sun don't pulse like Gray says they do.
"By all measures, this star is almost identical to our sun," said Marcy of the University of California-San Francisco. "And the remarkable thing is our sun, of course, is not oscillating with a four-day oscillation period at all, nor do any other solar-like stars."
A telescope can't settle the dispute
So why not just put a telescope in space and look? The planet is one billion times fainter than the star, and is outshone by the glare of the star.
"It would be like standing 10 miles from a nuclear explosion and trying to pick out the firefly that was 10 feet from the bomb blast. You can't see it," said Paul Butler, also of the University of California-San Francisco.
Will we know? Eventually. And both sides predict the other will eventually concede.
Related story:
- Astronomers find planets around far-off stars - April 22, 1996
Related sites:
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- Gray's Pulsing Star
- San Francisco State University - Dr. Geoff Marcy and Dr. Paul Butler
- Binary Star Animation
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