Nearby Venus is looking a bit more Earthlike, with frequent bursts of lightning confirmed by a European space probe.
For nearly three decades, astronomers have said Venus probably had lightning — ever since a 1978 NASA probe showed signs of electrical activity in its atmosphere. But experts weren't sure because of signal interference.
Now a magnetic antenna on the European Space Agency's Venus Express probe proved that the lightning was real.
"We consider this to be the first definitive evidence of abundant lighting on Venus," David Grinspoon of the Denver Museum of Nature and Science told reporters Wednesday at a briefing in Paris.
The finding is significant because lightning affects atmospheric chemistry, so scientists will have to take it into account as they try to understand the atmosphere and climate of Venus, he said.
The lightning is cloud-to-cloud and about 35 miles (55 kilometers) above the surface, said C.T. Russell, a geophysics professor at the University of California at Los Angeles and lead author of a paper on the Venusian fireworks. It is being published in Thursday's issue of the journal Nature.
Bursts of electrical energy from lightning are something that scientists have long theorized could provide the spark of life in primordial ooze.
But not on Venus.
"If life was ever something serious to talk about on Venus, it would be early in its history, not in its current state," said Sean Solomon of the Carnegie Institution of Washington, who was not part of the research team. "It's a very unforgiving atmosphere."
The idea of Earthlike lightning is fascinating, Russell said. However, you couldn't see it from Venus' surface — nor would you want to look, because the Venusian atmosphere is 100 times more dense than Earth's, is about 900 degrees Fahrenheit (500 degrees Celsius) hotter and has clouds of sulfuric acid, he said.
"It may be Earth's 'evil twin,' but it is in many respects Earth's twin," Russell said.
What excites astronomers most about the lightning discovery is simply the coolness factor.
Venus' weather forecasts have long thought to be "kind of boring ... steady winds for the next 400 years," said Allan Treiman, a senior scientist at the Lunar and Planetary Institute in Houston, who isn't affiliated with the research. The idea of lightning, he said, adds a spark to Venus' weather.
AP science writer Malcolm Ritter in New York contributed to this report.