Agenda spat at UN climate talks as top official sees chance to ask ‘difficult questions’ in Dubai
BERLIN (AP) — Nations resumed talks on tackling global warming Monday with the aim of shaping a deal that might put the world on track to prevent a dangerous increase in temperatures, as the U.N.’s top climate official called for…
Single Atom X-rayed For First Time in Breakthrough That Will ‘Transform the World’
Many laymen will not be aware that science has never been able to X-ray a single atom.
The best that current state-of-the-art synchrotron scanners can manage is to X-ray an attogram—about 10,000 atoms—but the signal produced by a single atom is so weak that conventional detectors cannot be used. Until now.
This landmark feat was achieved thanks to a purpose-built synchrotron instrument at Argonne National Laboratory in Illinois using a technique known as SX-STM (synchrotron X-ray scanning tunneling microscopy).
The researchers behind the breakthrough say it paves the way for finding cures for major life-threatening diseases, the development of superfast quantum computers, and other advancements in materials and eco-science.
Atoms are the particles that build molecules, and the limit to which any substance can be broken down chemically. There are as many in a golf ball as golf balls would fit into Earth.
SX-STM can now measure them to an infinitesimal degree. The feat has been described as the ‘holy grail’ of physics, and a long-standing dream of Professor Saw Wai Hla of Ohio State University, the lead author on the paper explaining the discovery.
“Atoms can be routinely imaged with scanning probe microscopes—but without X-rays one cannot tell what they are made of,” explained Dr. Hla. “We can now detect exactly the type of a particular atom, one atom-at-a-time, and can simultaneously measure its chemical state. This discovery will transform the world.”
Since its discovery by Roentgen in 1895, X-rays have been used in dozens of applications and fields, from medical examinations to security screenings in airports.
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NASA’s Mars rover Curiosity is equipped with an X-ray device to examine the composition of the rocks.
An important usage of X-rays in science is to identify the type of materials in a sample. Over the years, the quantity of materials in a sample required for X-ray detection has been greatly reduced thanks to the development of synchrotron X-rays.
SX-STM collects excited electrons, particles on the outside of an atom that move around the protons and neutrons inside, and the spectrum thus produced is like a fingerprint that enables the precise detection of what the atom is.
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“The technique used, and concept proven in this study broke new ground in X-ray science and nanoscale studies,” said first author Tolulope Michael Ajayi, a PhD student at Ohio.
“More so, using X-rays to detect and characterize individual atoms could revolutionize research and give birth to new technologies in areas such as quantum information and the detection of trace elements in environmental and medical research, to name a few.”
“This achievement also opens the road for advanced materials science instrumentation.”
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Astronomers Discover Hundreds of Mysterious Filaments Pointing Towards Our Milky Way’s Massive Black Hole
Astronomers have found hundreds of mysterious filaments pointing towards the Milky Way’s supermassive black hole, which could uncover fresh secrets about the dark abyss at the centre of our galaxy.
The strange horizontal strands are 25,000 light years from Earth and have been likened to spokes spreading out on a wheel.
“It was a surprise to suddenly find a new population of structures that seem to be pointing in the direction of the black hole,” said Professor Farhad Yusef-Zadeh, of Northwestern University.
“I was actually stunned when I saw these. We had to do a lot of work to establish that we weren’t fooling ourselves. And we found that these filaments are not random but appear to be tied to the outflow of our black hole.
“By studying them, we could learn more about the black hole’s spin and accretion disk orientation. It is satisfying when one finds order in a middle of a chaotic field of the nucleus of our galaxy.”
Known as Sagittarius A*, the black hole is a staggering four million times the mass of our Sun.
Positioned radially, the filaments measure less than 10 light years in length and look like the dots and dashes of Morse code, punctuating only one side of Sagittarius A*.
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The new discoveries are being made possible by enhanced technology, particularly from the South African Radio Astronomy Observatory’s (SARAO) MeerKAT telescope.
To uncover the filaments, estimated to be about six million years old, the researchers used a technique to remove the background and smooth the noise from images to isolate them from surrounding structures.
“The new MeerKAT observations have been a game changer,” said Prof. Yusef-Zadeh, lead author of the paper published in The Astrophysical Journal Letters. “The advancement of technology and dedicated observing time have given us new information. It is really a technical achievement from radio astronomers.”
He believes the filaments, pointing radially toward the black hole, appear to be tied to activities in the galactic center.
They appear to emit thermal radiation, accelerating material in a molecular cloud. There are several hundred vertical compared to just a few hundred horizontal.
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The new discovery is filled with unknowns and work to unravel its mysteries has just begun. For now, he can only consider a plausible explanation about the new population’s mechanisms and origins.
“We think they must have originated with some kind of outflow from an activity that happened a few million years ago.
“It seems to be the result of an interaction of that outflowing material with objects near it. Our work is never complete. We always need to make new observations and continually challenge our ideas and tighten up our analysis.”
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Black holes are formed when a dying star collapses inward under the pressure of its own weight. The pull of gravity is so strong that even light can’t escape. This is what makes them invisible. This leads to a supernova, a star’s extremely powerful explosion.
Supermassive black holes can be billions the size of our sun and astronomers believe they can be found at the centre of all large galaxies.
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1st-ever Mars livestream! Watch it here
[youtube https://www.youtube.com/watch?v=4qyVNqeJ6wQ&w=800&h=450]The 1st-ever Mars livestream is scheduled to begin at noon ET (16 UTC, 18 CEST) today and last for one hour.
Wow! A Mars livestream?!
What next? The European Space Agency (ESA) said today (June 2, 2023) that it intends to broadcast a livestream – the first ever – from the red planet Mars. The livestream will last for one hour, as live images stream down directly from Mars roughly every 50 seconds. The livestream is scheduled to begin today at noon ET (16 UTC, 18 CEST). Watch in the viewer above.
And get live updates via @esaoperations on Twitter and with the hashtag #MarsLIVE.
On Friday, join us for one hour of the first-ever #MarsLIVE stream??https://t.co/0pnQvr6teY
To celebrate the 20th birthday of #MarsExpress, this will be the closest you can get to a live view from the Red Planet. Find out more?? https://t.co/jYz6k9ym6u pic.twitter.com/Wgs9a41g8c
— ESA Operations (@esaoperations) May 31, 2023
Will it work?
The images will come from the Visual Monitoring Camera on board ESA’s Mars Express orbiter. James Godfrey, Spacecraft Operations Manager at ESA’s mission control center in Darmstadt, Germany, said:
This is an old camera, originally planned for engineering purposes, at a distance of almost three million kilometers [2 million miles] from Earth – this hasn’t been tried before and to be honest, we’re not 100% certain it’ll work …
But I’m pretty optimistic. Normally, we see images from Mars and know that they were taken days before. I’m excited to see Mars as it is now – as close to a Martian ‘now’ as we can possibly get!
Mars Express 20th birthday
ESA wrote at its YouTube page:
On Friday, to celebrate the 20th birthday of ESA’s Mars Express, you’ll have the chance to get as close as it’s currently possible to get to a live view from Mars. Tune in to be among the first to see new pictures roughly every 50 seconds as they’re beamed down directly from the Visual Monitoring Camera on board ESA’s long-lived and still highly productive Martian orbiter.
Bottom line: The European Space Agency hopes to broadcast the 1st-ever Mars livestream today (June 2, 2023). Tune in at EarthSky.
Super-Earth and mini-Neptune in synchronized dance
Among exoplanets in our galaxy, super-Earths and mini-Neptunes are two of the most common types. Even though neither exists in our own solar system, astronomers have discovered many in other solar systems. Now, researchers at the University of Liège in Belgium say they have found a pair of these worlds in another solar system 150 light-years away. What makes this system extra interesting, however, is that these two planets are in a synchronous dance around their red dwarf star. The astronomers made the discovery using NASA’s Transiting Exoplanet Survey Satellite (TESS) and ground-based telescopes.
The researchers first published their peer-reviewed findings in Astronomy and Astrophysics on April 12, 2023. The University of Liège announced the discovery on May 25, 2023.
A collaborative discovery
Researchers in Europe and the U.S. collaborated to make the discovery, using data from both TESS and ground-based telescopes. Astrophysicist Francisco J. Pozuelos, the lead author, explained:
TESS is conducting an all-sky survey using the transit method, that is, monitoring the stellar brightness of thousands of stars in the search for a slight dimming, which could be caused by a planet passing between the star and the observer. However, despite its power to detect new worlds, the TESS mission needs support from ground-based telescopes to confirm the planetary nature of the detected signals.
TESS is designed specifically to search for exoplanets, planets orbiting other stars. This includes planets like super-Earths and mini-Neptunes, as well as Earth-sized rocky worlds.
A super-Earth and mini-Neptune
The two planets – TOI-2096 b and TOI-2096 c – are both larger than Earth. TOI-2096 b isn’t much bigger though, with a radius only 1.2 times that of Earth. This makes it a super-Earth, a rocky world larger than our own planet, but smaller than Neptune.
TOI-2096 c, on the other hand, is 1.9 times Earth’s radius. The researchers say that this likely makes it a mini-Neptune. It may have a small rocky and icy core, but it would be enveloped in a deep, thick atmosphere rich in either hydrogen or water. That means it would be similar to the ice giants in our solar system, Uranus and Neptune, but smaller. But these exoplanets also offer a unique look at both super-Earths and mini-Neptunes and how they may have formed. Co-author Mathilde Timmermans said:
These planets are of crucial importance given their sizes. The formation of super-Earths and mini-Neptunes remains a mystery today. Several formation models try to explain it, but none fits the observations perfectly. TOI-2096 is the only system found to date with a super-Earth and a mini-Neptune precisely at the sizes where the models contradict each other. In other words, TOI-2096 may be the system we’ve been looking for to understand how these planetary systems have formed.
Two worlds in a synchronized dance
A super-Earth and mini-Neptune in the same system is interesting on its own. But there’s more. The orbits of the two planets are synchronized with each other.
In the same time that the outer planet completes one orbit, the inner planet completes two. You could say that the planets are in a kind of cosmic dance with each other. Timmermans explained:
Making an exhaustive analysis of the data, we found that the two planets were in resonant orbits: for each orbit of the outer planet, the inner planet orbits the star twice.
Their periods are, therefore, very close to being a multiple of each other, with about 3.12 days for planet b and about 6.38 days for planet c. This is a very particular configuration, and it causes a strong gravitational interaction between the planets. This interaction delays or accelerates the passage of the planets in front of their star and could lead to the measurement of the planetary masses using larger telescopes in the near future.
Super-Earth and mini-Neptune observations with Webb
Luckily, these two planets are well-suited for observations with NASA’s Webb Space Telescope. Pozuelos said:
Furthermore, these planets are among the best in their category to study their possible atmospheres. Thanks to the relative sizes of the planets with respect to the host star, as well as the brightness of the star, we find that this system is one of the best candidates for a detailed study of their atmosphere with the JWST space telescope. We hope to be able to do this quickly by coordinating with other universities and research centers. These studies will help confirm the presence of an atmosphere, extensive or not, around planets b and c, thus giving us clues as to their formation mechanism.
Bottom line: Astronomers say they’ve discovered a super-Earth and mini-Neptune exoplanet system where the orbits of the two worlds are synchronized in a cosmic dance.
Source: A super-Earth and a mini-Neptune near the 2:1 MMR straddling the radius valley around the nearby mid-M dwarf TOI-2096
Venus after sunset: Greatest elongation on June 4, 2023
When to watch: Venus came into view after sunset in December 2022 and has been visible in the evening sky throughout the first half of 2023. Greatest elongation – when Venus will be farthest from the sunset – happens on June 4, 2023. Afterwards, Venus will quickly sink toward the sunset as it races toward its sweep between the Earth and sun around mid-August 2023.
Where to look: Look in the sunset direction while the sky is darkening. You can’t miss Venus as the dazzling evening “star.”
Greatest elongation is at 11 UTC on June 4. That’s a whole-Earth time … for all of us, Venus will still appear in our evening sky, in the west after sunset. At this elongation, the distance of Venus from the sun on the sky’s dome is 46 degrees.
Magnitude at greatest elongation: Venus shines at magnitude -4.4.
Through a telescope: Venus appears 49% illuminated, in a first quarter phase, 23.56 arcseconds across.
Note: As the sun’s 2nd planet, Venus is bound by an invisible tether to the sun in our sky. It’s always east before sunrise, or west after sunset (never overhead at midnight). Venus is the brightest planet visible from Earth and shines brilliantly throughout every morning or evening apparition. Greatest elongation happens when Venus is farthest from the sun on the sky’s dome.
For precise sun and Venus rising times at your location:
Old Farmer’s Almanac (U.S. and Canada)
Stellarium (free online planetarium program)
Venus after sunset in 2023 Northern Hemisphere
Venus after sunset in 2023 Southern Hemisphere
A comparison of elongations
Not all of Venus’s greatest elongations are created equal. That’s because the farthest from the sun that Venus can ever appear on the sky’s dome is about 47.3 degrees. On the other hand, the least distance is around 45.4 degrees.
Elongations are also higher or lower depending on the time of year they occur and your location on Earth.
Venus events from late 2022 into 2024
October 22, 2022: Superior conjunction (passes behind sun from Earth)
June 4, 2023: Greatest elongation (evening)
August 13, 2023: Inferior conjunction (races between Earth and sun)
October 23, 2023: Greatest elongation (morning)
June 4, 2024: Superior conjunction (passes behind sun from Earth)
Bottom line: At greatest eastern elongation on June 4, 2023, Venus is as far from the sunset as it will be for this evening apparition.
Mars and the Beehive! See them together on June 1 and 2
Mars and the Beehive
On the evenings of June 1 and 2, 2023, you can spot Mars as it passes through a background star cluster known as the Beehive in Cancer the Crab. In fact, Mars appears as a big, bright ruby surrounded by tiny diamonds of distant stars.
First, to find Mars, look for brilliant Venus in the west, which at magnitude -4.3, wants to steal the show. You may also notice two bright stars strung out to one side of Venus. These are the twin stars in Gemini, Pollux and Castor. Above Venus and this duo is a bright, reddish light … that’s Mars. And if you’re in a dark-sky site or have binoculars, you can spot the smattering of stars beside the red planet.
A closer look at the Beehive star cluster
You’ll want binoculars to get a good look at just some of the 1,000 stars in the Beehive. While you can spot the cluster with your eyes alone, they will appear as a misty patch. However, with optical aid, the true nature of this star cluster comes alive.
The stars in this cluster lie about 577 light-years distant. So when you gaze at the Beehive, think about how many planets might reside among these 1,000 stars. We already know of at least two (Pr0201b and Pr0211b).
Do you have a photo to share? Submit it at EarthSky Community Photos. We sure enjoy seeing them.
Bottom line: Spot Mars and the Beehive star cluster together on June 1 and 2, 2023. You’ll want binoculars to get a good view of the starry cluster making a sparkling background for the red planet.
Want to see more night sky events? Visit EarthSky’s night sky guide
Our charts are mostly set for the northern half of Earth. To see a precise view from your location, try Stellarium Online.
Searching for habitable exoplanets in the soot zone
We think of habitable exoplanets as residing in a star’s habitable zone. That makes sense, right? It’s the region around a star where liquid water might exist, perhaps on a rocky planet similar to Earth. But there might be another important zone – related to habitability – that astronomers have mostly overlooked: the soot zone. Researchers at the University of Michigan said on May 25, 2023, that astronomers could expand the search for habitable exoplanets by taking the soot zone into account.
This zone in a protoplanetary disk – or planet-forming – is the space between the star and the soot line.
The researchers published their peer-reviewed findings in The Astrophysical Journal Letters on May 25, 2023.
Expanding the search for habitable exoplanets
The habitable zone is typically the first place that astronomers look for potentially habitable planets. That is based on what we know about our own solar system, and how the Earth has been able to hold onto its oceans and other water. Earth resides within the sun’s habitable zone while Mars and Venus are near the outskirts.
But astronomer Ted Bergin, who led the study, and his colleagues want to also consider the soot zone. The soot zone is the space between the star and the soot line. The soot line, specifically, is the outer boundary near a star where solid carbon molecules are destroyed and sublimate into gas. They become volatile carbon compounds instead of remaining as solid ones. Volatiles are chemical elements and compounds that can vaporize easily.
Planets in this zone may be rich in volatile carbon compounds, and those compounds could be quite different than anything on our own planet. What would such planets be like? Could they be habitable?
It adds a new dimension in our search for habitability. It may be a negative dimension or it may be a positive dimension. It’s exciting because it leads to all kinds of endless possibilities.
Water-poor and carbon-poor Earth
But these planets may also be water-poor. That sounds bad for habitability, but Earth is water-poor as well. Surprisingly, our planet contains only 0.1% water by mass.
Because of such little water content, scientists have long thought that Earth formed inside the frost line, or water-ice line, which is farther out from the sun. Bodies beyond that line tend to have a greater amount of water, percentage-wise, like the icy moons with subsurface oceans.
We also think of Earth as carbon-rich, but, as with water, it’s carbon-poor. Scientists say that while our planet was forming, it received only about one carbon atom per 100 that were available in the protoplanetary disk. The soot line may be responsible for this. If the building blocks of the young Earth formed inside the soot line, closer to the sun, then the volatile carbon compounds would have been turned into gas. That would limit the amount of solid carbon available for the forming planet.
Planets between the soot line and frost line
The study also focuses on exoplanets born between the soot line and frost line. There aren’t any in our own solar system, but astronomers have discovered many in other solar systems. They are typically super-Earth and mini-Neptune worlds. Both are larger in mass than Earth, but smaller in mass than Neptune. They are also the most common type of exoplanets found so far. Bergin said:
These are either big rocks or small gas giants; that’s the most common type of planetary system. So maybe, within all those other solar systems out in the Milky Way galaxy, there exists a population of bodies that we haven’t recognized before that have much more carbon in their interiors. What are the consequences of that? What this means for habitability should be explored.
Hazy methane atmospheres
The researchers modeled what these planets would be like, and found that they would likely have very hazy atmospheres. In the study, these planets, in the soot zone, are silicate-rich, with between 0.1% and 1% carbon by mass. They also have variable amounts of water. The models suggested that these worlds would outgass volatile carbon compounds and develop methane-rich atmospheres. The methane atmosphere would produce hazes, due to interaction with photons from the planets’ host stars. This is similar to how the hydrocarbon haze in Titan’s atmosphere is produced. Bergin explained:
Planets that are born within this region, which exists in every planet-forming disk system, will release more volatile carbon from their mantles. This could readily lead to the natural production of hazes. Such hazes have been observed in the atmospheres of exoplanets and have the potential to change the calculus for what we consider habitable worlds.
So, are those exoplanets habitable?
This could mean that a planet like this is potentially habitable, since the haze is evidence for a possibly carbon-rich mantle on the planet. And life – as we know it on Earth – is based on carbon. But with potentially more carbon and methane-rich atmospheres, these worlds would be quite unlike Earth in many ways.
If this is true, then there could be a common class of haze planets with abundant volatile carbon, and what that means for habitability needs to be explored. But then there’s the other aspect: What if you have an Earth-sized world, where you have more carbon than Earth has? What does that mean for habitability, for life? We don’t know, and that’s exciting.
NASA’s James Webb Space Telescope (JWST) will be able to look at some of these worlds, as the paper notes:
Such hazes, and the methane that drives their formation, are detectable via JWST transit spectroscopy, as demonstrated here, especially around stars lower in mass (and therefore size) than the sun.
That, too, will be exciting.
Bottom line: Astronomers say that habitable exoplanets could form in the soot zone around young stars. They could be rich in volatile carbon compounds, different from Earth.
Source: Exoplanet Volatile Carbon Content as a Natural Pathway for Haze Formation
Ancient ocean on Mars? Chinese rover finds marine sediments
We know that Mars had rivers and lakes in the distant past. But what about oceans? There is indeed tentative evidence for an ancient ocean in the northern hemisphere. However, scientists have been debating that evidence for decades. But now, researchers in China and the U.S. say they have found new clues in marine sedimentary rocks in Utopia Planitia that may prove the existence of that ocean. China’s Zhurong rover discovered the sedimentary formations. The researchers announced the tantalizing findings in Science China Press on May 21, 2023.
Professor Long Xiao from the School of Earth Sciences at China University of Geosciences led the research team. The team published its accepted peer-reviewed paper in National Science Review on May 18, 2023. The paper, still undergoing final editing, is available as a PDF.
New evidence for ancient ocean on Mars
China’s Zhurong rover has been exploring its landing site on the southern edge of Utopia Planitia in the northern hemisphere of Mars. This is within the northern lowlands that some scientists say was likely once an ocean floor. The rover’s newest findings now bolster that possibility. The rover has been studying the rocks in the area with its multispectral camera (MSCam), and the science team says that Zhurong has found marine sedimentary rocks. While most other data supporting the ocean hypothesis has come from orbiting spacecraft, this new data is in situ (on site).
It is the Vasitas Borealis Formation (VBF) that the mission scientists interpret to be marine sedimentary rocks. As the paper explains:
Decades of research using remotely-sensed data have extracted evidence for the presence of an ocean in the northern lowlands of Mars in the Hesperian, but these claims have remained controversial due to the lack of in situ analysis of the associated geologic unit, the Vastitas Borealis Formation (VBF). The Tianwen-1/Zhurong rover was targeted to land within the VBF near its southern margin and has traversed almost 1.2 miles (2 km) southward toward the interpreted shoreline. We report here on the first in situ analysis of the VBF that reveals sedimentary structures and features in surface rocks that suggest that the VBF was deposited in a marine environment, providing direct support for the existence of an ancient (Hesperian) ocean on Mars.
Multispectral images provide clues
Zhurong has been gradually moving south toward what is thought to be an ancient coastline. The rover has taken 106 panoramic images so far during its travels. Mission scientists have been studying the multispectral images for clues about the rocks’ composition and origin. They found bedding structures that are different from the usual volcanic rock deposits on Mars.
In addition, they were different from rock formations created by blowing sand.
A shallow sea environment
Indeed, the images revealed bidirectional flow, a sign of possible low-energy tidal currents. They are similar to formations created in shallow marine environments on Earth. The mission team named this region the Zhurong Member. The rocks feature small-scale cross-bedding, lens-shaped flaser bedding and small channel structures.
The paper says:
Bidirectional current orientations are characteristically formed by regular opposite directions of tidal currents in terrestrial shallow marine environments, and uncommonly in fluvial environments. Although aeolian deposits on Mars also contain some small-scale cross-laminations, the lack of larger structures indicative of aeolian environments supports the interpretation that these are of shallow marine origin.
The images also showed that the layers in the cross-bedding overlap and tilt in two opposite directions. The thickness of the strata, as well as the size of sand grains, also differs. This is evidence for a bidirectional water flow pattern. On Earth, this is common in littoral-shallow sea environments.
Ancient shorelines of an ocean on Mars and a wild river
Last year, researchers at Penn State and Caltech said they discovered definitive traces of an old shoreline in Mars’ northern hemisphere.
And just last week, scientists announced that the Perseverance rover has found evidence for a rollicking river. It was the deepest and fastest-flowing river yet observed – now all dried up of course – by any rover or lander.
The new findings from the Zhurong rover would seem to support this, adding another crucial piece to the puzzle. That ocean would have been vast, covering most of the northern hemisphere of Mars. The next question, of course, is whether it supported any kind of life. It will be interesting to see what else Zhurong finds in its travels, as well as any future missions to this now-dry ocean wonderland.
Bottom line: Scientists in China say that the Zhurong rover has found new evidence for an ancient ocean on Mars, sedimentary rocks formed in a shallow marine environment. The ocean would have covered hundreds of thousands of square kilometers. They estimate the ancient Martian shoreline to be 3.5 billion years old.
Source: Evidence for marine sedimentary rocks in Utopia Planitia: zhurong rover observations
Via Science China Press/ Eurekalert!
Frank Drake, SETI visionary, born on this date
Astronomer Frank Drake
May 28, 2023, would be the 93rd birthday of astronomer Frank Drake. Sadly, he passed away recently, on September 2, 2022. Drake was an early visionary in the search for other civilizations in our Milky Way galaxy.
In 1960, Drake spearheaded Project Ozma, the first modern attempt to listen for radio transmissions from otherworldly intelligences.
Then, on November 1, 1961, Drake, Carl Sagan and other astronomers met at the site of the Green Bank Telescope in Green Bank, West Virginia. And at that meeting, Drake presented what has become known as the Drake equation.
Scientists and others found the Drake equation fascinating then … and they still do. The Drake equation is a tool for contemplating how many intelligent civilizations might be capable of communicating with us from elsewhere in the galaxy. From Drake’s formulation of the equation – and the 1961 meeting in Green Bank – the field of research and scientific organization known as SETI, the search for extraterrestrial intelligence, was born.
Frank Drake presenting the keynote on the history and future of SETI at our #decodingintelligence conference today. More photos to come! #seti pic.twitter.com/p3IJHVSoTf
— The SETI Institute (@SETIInstitute) March 14, 2018
What is the Drake equation?
The Drake equation is a mathematical formula for thinking about how many civilizations beyond Earth might be able to communicate with us. Nowadays when you hear astronomers speak of life beyond Earth, they might be focused on biosignatures. That’s where they are looking for evidence of life, but for simple or multicellular life. For example, possible life forms under rocks on Mars or in the atmosphere of Venus. However, the Drake equation focuses on something different. In fact, it’s the search for advanced and communicating civilizations.
Thus, here is the Drake equation: N = R* • fp • ne • fl • fi • fc • L
Breaking down the Drake equation
N = the number of civilizations in our galaxy with which communication might be possible
R* = the average rate of star formation in our galaxy
fp = the fraction of those stars that have planets
ne = the average number of planets that can potentially support life per star that has planets
fl = the fraction of planets that could support life that actually develop life at some point
fi = the fraction of planets with civilizations that actually go on to develop intelligent life
fc = the fraction of civilizations that develop a technology that releases detectable signs of their existence into space
L = the length of time for which such civilizations release detectable signals into space
As originally formulated, the Drake equation is less a true mathematical formula and more a way to start a conversation. So the value of N – the number of civilizations with which we might communicate – is difficult to determine if you don’t have solid numbers on all the factors that need to be considered.
So do astronomers know the rate of star formation in our Milky Way? Yes, approximately. The rate of star formation is somewhere around 3 solar masses per year. Next, do they know how many stars form planets? Of course, we didn’t know that number in 1961, but now we do. In fact, the answer is thought to be that most, if not all, of them form planets.
But, as you go onward in the equation, the state of our knowledge begins to falter. First, we don’t know the mean number of planets that could support life per star with planets. Second, we don’t know the fraction of life-supporting planets that develop life. And so on.
Drake equation revisited
Additionally, a wonderful thing about the Drake equation, is it continues to inspire fresh thinking about extraterrestrial life among astronomers. So in 2016, Adam Frank and Woodruff Sullivan put their heads together to publish a paper in the journal Astrobiology in which they presented the Drake equation in a new light. Then they noted that technological advancements in astronomy had made better estimates possible of two Drake equation factors:
The fraction of stars with planets, fp, is now estimated to be 1.0, meaning all stars have planets
The number of planets per star where conditions are suitable for life, ne, is now estimated to be 0.2, meaning one in five planets can support life
A case for rewriting the Drake equation
In May 2021, John Gertz made a case for rewriting the Drake equation in a paper accepted for publication by the Journal of the British Interplanetary Society. Here are Gertz’s thoughts on the Drake equations variables:
R*, the mean rate of star formation changes over the history of our galaxy. Plus, what about other galaxies? The rate of star formation would be different. In his May 2021 paper, Gertz suggested changing R* to Ns. That’s for the number of candidate stars in the Milky Way that fall within our field of view. He pointed out that 80% of these stars would be stars not so very different from our sun.
Fp, the fraction of stars that have planets, is no longer a big unknown. That’s because we now know that planets around stars are quite common.
Ne, the number of rocky planets in a star’s habitable zone, is too limiting. Plus the presence of an atmosphere and water are important considerations. But so are the countless moons where life could exist around planets outside a star’s habitable zone. So Gertz recommends replacing this variable with Ntb. That stands for the total number of bodies that could support life on or beneath their surfaces.
Currently, Fl, the fraction of planets that develop life, is unknowable. Also, it’s still not understood the origin of life on Earth, much less how common or rare it is in the universe.
Fi, the fraction of planets with life that develop intelligence, is also unknowable. If we don’t know how common life may be in the universe, we don’t know how common intelligent life may be.
More of Gertz’s suggested revisions
Fc, the fraction of intelligent civilizations technologically capable and actively trying to communicate with us, doesn’t take into consideration the vast expanses that communication would have to travel between our home worlds. But we could also unintentionally stumble across a signal (perhaps the Wow! signal?). Then a better variable, Gertz says, is Fd, the fraction of technological life that is detectable by any means. However, the problem may not be the civilization sending us a message. Instead, the problem could be that we aren’t advanced enough to detect or receive it.
L, the length of time a civilization is communicative, depends on how long they can sustain themselves before they either self-destruct or something external (asteroid, supernova or the like) takes them out. We don’t know the answer, either for ourselves or for an alien civilization. This variable is the one that Carl Sagan considered most uncertain. Gertz’s ideas about L mesh nicely with Avi Loeb’s assertion that ‘Oumuamua is of alien origin. Gertz commented:
The Drake equation was predicated upon the notion that there is a finite number of currently existing alien civilizations ensconced among the stars, some of whom will be signaling their presence to us using radio or optical lasers. However, this ignores another school of thought which holds that ET’s far better strategy would be to send physical probes to our solar system to surveil and ultimately make contact with us. Such probes could represent information from innumerable civilizations, many of whom may have long ago perished. If this is the case, Drake’s L is irrelevant, since the probe might far outlive its progenitor, and his N reduces to one, the single probe that makes its presence known to us through which alone we might communicate with the rest of the galaxy.
Gertz’s final version of the Drake equation
What’s left is John Gertz’s updated take on the Drake equation: N = ns • fp • ntb • fl • fi • fd • L
ns is the number of spots on the sky within our field of view
fp is the fraction of stars with planets
ntb is the average number of bodies within each that could engender life
fl is the fraction of those that actually do give birth to life
fi is the fraction of systems with life that evolves technological intelligence
fd is the fraction of technological life that is detectable by any means
L is the duration of detectability
Frank Drake knew the uncertainties
Even with this new formula, as when Drake originally formulated his equation, uncertainty pervades. Gertz said:
The Drake equation sets out to determine N, the number of extant communicating civilizations. There is simply no way to determine this by any known means other than by making contact with our first ET and asking it what it might know of the matter. The failure of the Drake equation paradoxically makes a robust SETI program all the more important, since no amount of armchair speculation can determine N.
Where do SETI researchers go from here?
The plan is for radio wave and visible-light observations, combined with technological advances that will eventually let scientists survey one million nearby stars, the entire galactic plane and 100 nearby galaxies. Dedicated wide-field telescopes are one of the items on Gertz’s wish list for SETI.
Breakthrough Listen, a project Gertz is currently involved in, is a good start. It is the largest-ever scientific research program aimed at finding evidence of civilizations beyond Earth. Breakthrough Listen scans the radio spectrum with the world’s most powerful instruments. Gertz said:
Breakthrough Listen is a game-changer. Because of it, more SETI is accomplished in a single day than was ever before accomplished in a full year.
Funding will be the key to continued searches, and, with a lot of planning and maybe a little luck, to future success in finding an intelligent civilization in the wider universe.
Read more: SETI Institute expands search for aliens with VLA
Video resources on the Drake equation
For a more in-depth discussion about the Drake equation, watch the following two-part videos of 25 minutes each hosted by David Kipping of Columbia University.[youtube https://www.youtube.com/watch?v=dM_Pelfc92s&w=857&h=482] [youtube https://www.youtube.com/watch?v=kliJ-CFVLeE&w=857&h=482]
Bottom line: May 28, 2023, would be the 93rd birthday of astronomer Frank Drake. Drake was an early visionary in the search for other civilizations in our Milky Way galaxy and formulator of the Drake equation. In May 2021, John Gertz suggested reformulating the Drake equation.
Source: A New Empirical Constraint on the Prevalence of Technological Species in the Universe
Source: The Drake equation at 60