Possible sign of life detected in the atmosphere of Venus

This artistic illustration depicts the Venusian surface and atmosphere. Credit: ESO/M. Kornmesser

An international team of astronomers today announced the discovery of a rare molecule — phosphine — in the clouds of Venus. On Earth, this gas is only made industrially or by microbes that thrive in oxygen-free environments. Astronomers have speculated for decades that high clouds on Venus could offer a home for microbes — floating free of the scorching surface but needing to tolerate very high acidity. The detection of phosphine could point to such extra-terrestrial “aerial” life. Confirming the presence of life, however, will require much more work.

“When we got the first hints of phosphine in Venus’s spectrum, it was a shock!”, says team leader Jane Greaves of Cardiff University in the UK, who first spotted signs of phosphine in observations from the James Clerk Maxwell Telescope (JCMT), operated by the East Asian Observatory, in Hawaiʻi. Confirming their discovery required using 45 antennas of the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, a more sensitive telescope in which the European Southern Observatory (ESO) is a partner. Both facilities observed Venus at a wavelength of about 1 millimeter, much longer than the human eye can see — only telescopes at high altitude can detect it effectively.

The international team, which includes researchers from the UK, US and Japan, estimates that phosphine exists in Venus’s clouds at a small concentration, only about twenty molecules in every billion. Following their observations, they ran calculations to see whether these amounts could come from natural non-biological processes on the planet. Some ideas included sunlight, minerals blown upwards from the surface, volcanoes, or lightning, but none of these could make anywhere near enough of it. These non-biological sources were found to make at most one ten thousandth of the amount of phosphine that the telescopes saw.

To create the observed quantity of phosphine (which consists of hydrogen and phosphorus) on Venus, terrestrial organisms would only need to work at about 10% of their maximum productivity, according to the team. Earth bacteria are known to make phosphine: they take up phosphate from minerals or biological material, add hydrogen, and ultimately expel phosphine. Any organisms on Venus will probably be very different to their Earth cousins, but they too could be the source of phosphine in the atmosphere.

While the discovery of phosphine in Venus’s clouds came as a surprise, the researchers are confident in their detection. “To our great relief, the conditions were good at ALMA for follow-up observations while Venus was at a suitable angle to Earth. Processing the data was tricky, though, as ALMA isn’t usually looking for very subtle effects in very bright objects like Venus,” says team member Anita Richards of the UK ALMA Regional Centre and the University of Manchester. “In the end, we found that both observatories had seen the same thing — faint absorption at the right wavelength to be phosphine gas, where the molecules are backlit by the warmer clouds below,” adds Greaves, who led the study published today in Nature Astronomy.

Another team member, Clara Sousa Silva of the Massachusetts Institute of Technology in the US, has investigated phosphine as a “biosignature” gas of non-oxygen-using life on planets around other stars, because normal chemistry makes so little of it. She comments: “Finding phosphine on Venus was an unexpected bonus! The discovery raises many questions, such as how any organisms could survive. On Earth, some microbes can cope with up to about 5% of acid in their environment — but the clouds of Venus are almost entirely made of acid.”

The team believes their discovery is significant because they can rule out many alternative ways to make phosphine, but they acknowledge that confirming the presence of “life” needs a lot more work. Although the high clouds of Venus have temperatures up to a pleasant 30 degrees Celsius, they are incredibly acidic — around 90% sulfuric acid — posing major issues for any microbes trying to survive there.

ESO astronomer and ALMA European Operations Manager Leonardo Testi, who did not participate in the new study, says: “The non-biological production of phosphine on Venus is excluded by our current understanding of phosphine chemistry in rocky planets’ atmospheres. Confirming the existence of life on Venus’s atmosphere would be a major breakthrough for astrobiology; thus, it is essential to follow-up on this exciting result with theoretical and observational studies to exclude the possibility that phosphine on rocky planets may also have a chemical origin different than on Earth.”

More observations of Venus and of rocky planets outside our Solar System, including with ESO’s forthcoming Extremely Large Telescope, may help gather clues on how phosphine can originate on them and contribute to the search for signs of life beyond Earth.

Hubble’s latest portrait of the “Lord of the Rings”

NASA’s Hubble Space Telescope captured this image of Saturn on July 4, 2020. Two of Saturn’s icy moons are clearly visible in this exposure: Mimas at right, and Enceladus at bottom. This image is taken as part of the Outer Planets Atmospheres Legacy (OPAL) project. OPAL is helping scientists understand the atmospheric dynamics and evolution of our solar system’s gas giant planets. In Saturn’s case, astronomers continue tracking shifting weather patterns and storms. Credits: NASA, ESA, A. Simon (Goddard Space Flight Center), M.H. Wong (University of California, Berkeley), and the OPAL Team

Saturn is truly the lord of the rings in this latest portrait from NASA’s Hubble Space Telescope, captured on July 4, 2020, when the opulent giant world was 839 million miles from Earth. This new Saturn image was taken during summer in the planet’s northern hemisphere.

Hubble found a number of small atmospheric storms. These are transient features that appear to come and go with each yearly Hubble observation. The banding in the northern hemisphere remains pronounced as seen in Hubble’s 2019 observations, with several bands slightly changing color from year to year. The ringed planet’s atmosphere is mostly hydrogen and helium with traces of ammonia, methane, water vapor, and hydrocarbons that give it a yellowish-brown color.

Hubble photographed a slight reddish haze over the northern hemisphere in this color composite. This may be due to heating from increased sunlight, which could either change the atmospheric circulation or perhaps remove ices from aerosols in the atmosphere. Another theory is that the increased sunlight in the summer months is changing the amounts of photochemical haze produced. “It’s amazing that even over a few years, we’re seeing seasonal changes on Saturn,” said lead investigator Amy Simon of NASA’s Goddard Space Flight Center in Greenbelt, Maryland. Conversely, the just-now-visible south pole has a blue hue, reflecting changes in Saturn’s winter hemisphere.

Hubble’s sharp view resolves the finely etched concentric ring structure. The rings are mostly made of pieces of ice, with sizes ranging from tiny grains to giant boulders. Just how and when the rings formed remains one of our solar system’s biggest mysteries. Conventional wisdom is that they are as old as the planet, over 4 billion years. But because the rings are so bright – like freshly fallen snow – a competing theory is that they may have formed during the age of the dinosaurs. Many astronomers agree that there is no satisfactory theory that explains how rings could have formed within just the past few hundred million years. “However, NASA’s Cassini spacecraft measurements of tiny grains raining into Saturn’s atmosphere suggest the rings can only last for 300 million more years, which is one of the arguments for a young age of the ring system,” said team member Michael Wong of the University of California, Berkeley.

Two of Saturn’s icy moons are clearly visible in this exposure: Mimas at right, and Enceladus at bottom.

This image is taken as part of the Outer Planets Atmospheres Legacy (OPAL) project. OPAL is helping scientists understand the atmospheric dynamics and evolution of our solar system’s gas giant planets. In Saturn’s case, astronomers continue tracking shifting weather patterns and storms.

Bidding farewell to a fine comet

Fiber-optic star trails, fireflies, the ISS & NEOWISE. July 17, 2020. This photo is a 52-minute star trail made from 526 consecutive shots, each six seconds long, ISO 800, 15mm at f/2.8, Nikon D810. Photo by Alan Studt.

Comet C/2020 F3 (NEOWISE) was the finest comet to grace the skies of the Northern Hemisphere in quite some years. Amateur astronomers and photographers the world over made fascinating observations and beautiful images of the comet and its surprisingly long tail. By July 5, NASA’s Parker Solar Probe had captured an image of the comet, from which astronomers also estimated the diameter of the comet nucleus at approximately 5 km. or about three miles; that’s a reasonably large size but around average for a comet. The large nucleus offered plenty of volatile materials for the Sun to stir into tail formation.

On July 23 the comet reached perigee with Earth and is now speeding toward the outer Solar System, not to revisit the inner planetary neighborhood for several thousands of years. So, though relatively near Earth the object is fading fast. Lately astronomers and astrophotographers have been grabbing the last views they will have of C/2020 F3 before it fades to obscurity.

Here are some photos made by members of the Cuyahoga Astronomical Association (CAA) as a cometary farewell of sorts:

C/2020 F3 NEOWISE as viewed from Veteran’s Memorial Park in Avon Lake just before 11 p.m., July 24, 2020. Photo by Alan Studt.

Alan Studt’s lovely portrait of the comet shows its tails remain, if faded, long and expansive. He wrote, “Beautiful night by the lake last night. Took these at Veteran’s Memorial Park in Avon Lake just before 11 p.m. Pretty large group of people hanging out. The comet was definitely much dimmer than the previous Friday.”

Technical Information: Tamron 70-200mm f/2.8 lens, on a Nikon D850.
The comet image is made from 14 shots (2.5 seconds, ISO 10,000, at 200mm, f/2.8). Stacked in Deep Sky Stacker & post processed in Lightroom and Photoshop. Seventy-five shots but got the best star field alignment using only 14 shots. Also used dark & flat frames.
C/2020 F3 NEOWISE as viewed from Letha House Park in Medina County, Ohio, at 10:36 p.m. July 24, 2020. Photo by James Guilford.

James Guilford was at Letha House Park, July 24, attempting to record detailed images of the comet nucleus and close tail. The green coloration of the comet was a surprise to him, even after reading the observations of others. “All of my comet shots Friday night show a green nucleus,” Guilford said, “and it grew brighter as I processed the images later. I’d have liked to have picked up more of the tail but, given the circumstances, I’m pretty happy with what I got.” Both he and other Letha House Park observers could see a green tint by eye through telescopes. He and others also report the comet was barely within the range of eyesight but only at its highest above the horizon and only via averted vision.

Technical Information: Canon EOS 6D Mk. 2, at prime focus of 1800mm FL Cassegrain telescope, eight light exposures plus darks, ISO 1250, 15 seconds per exposure, stacked in Starry Sky Stacker, processed in Photoshop.

C/2020 F3 NEOWISE nearly lost amongst the stars. Photo by Jon Salontay.

Jon Salontay also photographed the comet that Friday. Above we see how it is nearly lost, even to the camera, amongst the stars. Technical Info.: Time – 11:32 p.m., Canon T5i with 18-75mm zoom lens at 18 mm, exposure 30 seconds at F/5.6, ISO 800. Brightness & Contrast adjusted.

C/2020 F3 NEOWISE via telescope. Photo by Jon Salontay.

Salontay then turned his telescope on the “dirty snowball.” Technical Info.: Time – 12:13 a.m., July 25. Celestron 8-inch SCT on Advanced VX Mount, Canon T5i, 15 seconds, ISO 1600. No out-of-camera adjustment.

He wrote, “Although I’ll try to follow it telescopically over the next month, how about another comet before the year is out? It’s a lot of fun.”

Penumbral Lunar Eclipse: July 4 – 5

NASA Solar and Earth images, illustration by James Guilford.
A penumbral lunar eclipse occurs when the Moon passes through the thin outer portion of the shadow Earth casts out into space.

We’re fortunate that the night of July 4 is expected to be clear, and not just for the traditional booms and flashes of celebratory fireworks. Our Moon is getting in on the act, albeit with a much more subtle display in the form of a penumbral eclipse. The eclipse will take place from 11:07 PM to 1:52 AM EDT with maximum eclipse at 12:31 AM July 5.

We say subtle because, unlike a total lunar eclipse, Earth’s Moon will not change to reddish/coppery colors. The Moon will instead become oddly shadowed for a Full Moon, as it enters the outer fringes of Earth’s shadow in space — the penumbra. Only the “top” portion of Luna will pass through the penumbra making this eclipse especially slight. Still, it’s worth a look and it won’t be at a particularly late hour. A deeper penumbral lunar eclipse will take place the night of November 30, 2020.

Moon is eclipsed when it passes through Earth's shadow. Credit: SkySafari / J. Guilford
Earth’s shadow runs away from the Sun into space and has two parts: the deep inner shadow or umbra, and the thin outer portion called the penumbra. The Moon is eclipsed when it passes through Earth’s shadow. Credit: SkySafari / J. Guilford

While it’s possible to view this eclipse with the unaided eye, binoculars will provide an enhanced view as would a small telescope.

Penumbral Lunar Eclipse of July 4 – 5, 2020 at Maximum Eclipse: 12:31 AM EDT. Simulation via SkySafari

And just in case there’s any confusion, lunar eclipses are perfectly safe to view and photograph — it’s moonlight — so nothing to worry about there.

If you shoot any photos or have impressions to share with us, you can do so via our Twitter — @Cuyastro

Penumbral Lunar Eclipse of July 4 – 5, 2020. Credit: NASA

NASA Eclipse Page available here: Penumbral Lunar Eclipse of July 4 – 5, 2020.