British researchers claimed to have detected a gas that indicates that microbes live on the inhospitable planet. But Dutch scientists have called their claims into question. How did they get it so wrong?
Image: picture-alliance/Planet-C
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Dutch researchers have called into question the recent research results of British astronomers who claimed to have discovered the gas phosphine high up in the atmosphere of Venus.
The team, led by Ignas Snellen from Leiden University, reexamined the original data and came to a completely different conclusion. The detection of the gas was not statistically significant, the researchers said, and may have simply been a measurement error. Their results have been published as a non-peer-reviewed preliminary study in the journal Astronomy & Astrophysics on the preprint platform arXiv.
The British astronomers announced the discovery of potential signs on life on Earth's neighbor on September 14 in the journal Nature Astronomy.
According to the British study, scientists working with telescopes located in Hawaii and Chile found signatures of clouds containing phosphine, a noxious gas that on Earth is associated with life.
"It's not a smoking gun," said study co-author David Clements, an astrophysicist at Imperial College London. "It's not even gunshot residue on the hands of your prime suspect, but there is a distinct whiff of cordite in the air, which may be suggesting something.''
Though Clements gave only a 10% probability to the presence of life on Venus, he was excited about the possibility.
On Earth, phosphine gas has been found to exist as the product of an industrial process or as an output of an unknown process in some animals and microbes.
Phosphine has been found as "ooze at the bottom of ponds, [in] the guts of some creatures like badgers and perhaps most unpleasantly associated with piles of penguin guano," Clements explained.
Meet the planets
The first close-ups of Pluto awed the world this week. A couple of decades ago, photos of Venus or Saturn taken from space had a similar effect on scientists. Join DW on an interplanetary photo safari!
Image: Reuters/NASA/APL/SwRI/Handout
Our solar system
Depending on who you ask, there are eight or nine planets in our solar system - some experts still count Pluto, while the International Astronomical Union (IAU) took away its planetary status in 2006. People were still excited when NASA presented the first high-res images of Pluto this week. Its neighbors all had their portrait taken as early as the 1960s.
Mercury
The spacecraft Mariner 10 left for the planet closest to the Sun in 1973. It took this picture of Mercury's moon-like surface in March 1974. The planet's distance to the Sun varies between 28.5 million miles (46 kilometers) and 43.5 million miles (70 kilometers), because its orbit isn't a perfect circle. Scientists were surprised to discover that Mercury had a small magnetic field.
Image: picture-alliance/dpa/Nasa
Venus
Mariner 10 took this first close-up of Mercury's direct neighbor on February 5, 1974. The picture was color-enhanced by NASA to bring out Venus' cloudy atmosphere - the planet is perpetually blanketed by a thick veil of clouds rich in carbon dioxide. Mariner 10's journey to Venus was a rocky one: the spacecraft's high-gain antenna developed problems and a mechanical issue caused a large fuel-loss.
Image: picture-alliance/dpa/Nasa
Earth
The first full-on photo of our planet as seen from outer space was taken by Lunar Orbiter 1 in August 1966. That was three years before a human being had ever set foot on the Moon, which can be seen in the foreground of this picture as a shadow. The now-iconic photo was one of a series of pictures taken in preparation for the Apollo missions that would eventually put a human on the Moon.
Image: picture-alliance/dpa/Nasa/Loirp
Mars
This close-up of Earth's neighbor is the first picture ever taken of another planet by a spacecraft. Mariner 4 snapped it on July 15, 1965. Scientists who had expected to see lakes, valleys and mountains were disappointed - instead of an Earth-like planet, they were treated to craters similar to those on the Moon. The New York Times wrote: "Mars is probably a dead planet."
Image: picture-alliance/dpa
Jupiter
Spacecraft Pioneer 10 took the planet's first close-up from roughly 80,780 miles (130,000 kilometers) away on November 19, 1973. Jupiter is our solar system's largest planet. At its equator, Jupiter's diameter is a whopping 88,846 miles (142,984 kilometers). Its mass is two-and-a-half times larger than the masses of all other planets combined.
Image: picture-alliance/dpa/UPI
Saturn
This first shot of the ringed planet was taken on Pioneer 10's follow-up mission, Pioneer 11, on August 31, 1979. It was a perilous adventure: as the spacecraft flew through Saturn's outer rings, it almost crashed into one of two new moons it discovered. Visible at the upper left-hand corner in this photo is Saturn's moon Titan.
One of the first glimpses scientists got of Uranus was of its rings. Voyager 2 took this shot of them in 1986. Scientists had to remote-fix the spacecraft's camera for it to be able to photograph the planet with the coldest atmosphere in our solar system (as low as -366 degrees Fahrenheit or -221 degrees Celsius). The device had malfunctioned while Voyager 2 was passing Saturn.
Image: picture-alliance/dpa/Consolidated
Neptune
Voyager 2 also took the first picture of Neptune in August 1989. The planet has four cloud features that scientists know about. For those who don't count Pluto, Neptune is the planet in our solar system that's furthest away from the sun: at an average of 2.8 billion miles (4.5 billion kilometers), that distance is 30 times greater than the one between the Sun and Earth.
Image: picture-alliance/dpa
Pluto
The fact that Pluto is not officially a planet anymore didn't detract from the excitement scientists and lay-people all over the world experienced when NASA released this first close-up of the copper-colored (dwarf-) planet taken by New Horizons on July 13, 2015. The spacecraft traveled 3 billion miles (4.88 billion kilometers) to the solar system's farthest reaches for this shot.
The astronomers explained, however, that at 30 miles (48 kilometers) above the surface, a thick layer of carbon dioxide cloud cools down to around room temperature and contains droplets with small amounts of water along with mostly sulfuric acid.
The authors speculated that any potential life would most likely be single-cell microbes existing within those acidic droplets.
Another possible explanation for the phosphine gas is volcanic activity, according to Justin Filiberto, a planetary geochemist at the Lunar and Planetary Institute in Houston. "I'm not skeptical, I'm hesitant,'' he said regarding the discovery.
London's Royal Observatory annually selects the best photos of the universe, entered in an annual astronomy photographer competition. Ahead of the prize announcement, here's a short list.
Image: Ben Bush
A planet is born
Photographer Martin Pugh was thrilled by what he photographed with his CDK 17 telescope in Chile in May 2019. Over many clear nights, he collected data and took precise light measurements. For 23 hours, the Australian exposed swirling hydrogen and documented the birth of a new planet.
Image: Martin Pugh
Upward view in Australia
Here, the astronomer's sober gaze and the photographer's enter an artistic alliance, drawing the viewer into the Milky Way's galactic core. The Lithgow Blast Furnace building is an icon of the Australian iron and steel industry. In it, Australian Jay Evans tried out a high-resolution megapixel camera for the first time. The result was anything but disappointing.
Image: Jay Evans
Solar eclipse with Venus
These extraordinary light conditions were in the crystal-clear air on one day at the ESO Observatory in La Silla, Chile. Using a complex technique, photographer Sebastian Voltmer captured a solar eclipse in an picture that also shows a brightly-shining Venus. Ninety-six individual images were calibrated, superimposed and fused into one glorious image.
Image: Sebastian Voltmer
Northern Lights on the Lofoten Islands
This snapshot was taken by the German photographer Andreas Ettl on Norway's Lofoten Islands. The remote area below the Arctic Circle is one of the world's best places to experience a spectacular light show of the aurora borealis, as depicted in this photo, titled "Hamnoy Lights."
Image: Andreas Ettl
Capturing galactic symmetry
With impressive technical precision, Andy Casely preserved a supernatural moment with the help of a high-powered telescope. In this stunning shot taken on a summer day in 2019, the photographer captured ringed Saturn peeking out from behind the large pock-marked face of the moon.
Image: Andy Casely
The moon over London
After three failed attempts, British photographer Mathew Browne finally succeeded in taking this somewhat eerie photo of the full moon in the British capital. Like a scene from Batman's Gotham City, the moon shines brightly from behind the jagged facade of the Shard skyscraper. The photographer only had a few minutes to take this special shot.
Image: Mathew Browne
Arctic dance of color
Stunning natural phenomena make it easy for photographers in the Icelandic region on the edge of the Arctic Circle to capture a good shot. But professional nature photographer Ben Bush takes it to the next level in this breathtaking picture awash in green light. To take this picture, Bush kneeled at the shore of the Atlantic Ocean at a temperature of #6 degrees C (-17 Fahrenheit).
Image: Ben Bush
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"I'm excited, but I'm also cautious,'' commented David Grinspoon, an astrobiologist at the Planetary Science Institute in Washington. "We found an encouraging sign that demands we follow up.''
NASA is currently considering its first missions to Venus since 1989.
This article was originally published on September 16, 2020 and has been updated on October 23, 2020 to reflect the publication of the new study on ArXiv.