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Scientists have harnessed the power of specially made nanostructures to enhance the neural response in a locust's brain to specific odors and to improve their identification of those odors.

In the beginning, the Universe was so hot and so dense that light could not travel far. Photons were emitted, scattered, and absorbed as quickly as the photons in the heart of the brightest stars. But in time the cosmos expanded and cooled to the point that it became transparent, and the birthglow of the Big Bang could traverse space and time for billions of years. We still see it as the microwave cosmic background. As the Universe expanded it grew dark, filled only with warm clouds of hydrogen and helium. In time those clouds collapsed to form the first stars, and light again filled the heavens.

None of the stars we see today were among those first stars. Modern stars are rich with elements such as carbon and iron. Heavier elements only formed in stellar cores and other astrophysical processes. The first stars we made only of hydrogen and helium. They must have been massive beasts, with fleeting lives that ended in brilliant supernova explosions. Only their remnants remain. There have been several deep sky searches for these first stars, but we have so far not seen them. There is some indirect evidence of them in the distant Universe, but we have not yet seen their light. Now a new study argues that the Nancy Grace Roman Space Telescope might capture their dying radiance.

How a TDE of a first-generation star might be observed. Credit: Chowdhury, et al

Formally known as the Wide-Field Infrared Survey Telescope (WFIRST), The Roman Space Telescope is scheduled to launch in late 2026. Like the JWST, it will observe the cosmos in infrared, but Roman will have a wider field of view. This will better enable it to find the highly redshifted light of the first stars. However, the authors note that given the short lifespan of these first stars, Roman will not likely observe them directly. They instead propose looking for evidence of these stars as they are consumed by a black hole.

Specifically, the team proposes looking for what are known as Tidal Disruption Events (TDEs). When a star passes near a black hole, the gravitational tidal forces of the black hole can rip the star apart. As a result, the remnants of the star can be strewn across a large arc. This process takes time and creates a stream of heated gas. The authors modeled the emission spectra of this gas for a first-generation star and found they have a unique signature that lasts for a considerable amount of time. Much of the light from such a TDE would be emitted in the strong ultraviolet, but since they would occur at a cosmic redshift of about z = 10, the light we see would be shifted to the infrared, making it observable by JWST and the Roman Space Telescope.

The authors note that the rate at which TDEs occur for first-generation stars depends on several factors, but given reasonable estimates Roman could expect to see tens of these TDEs per year. So in a few years, we might finally be able to capture the last dying light of the first stars.

Reference: Chowdhury, Rudrani Kar, et al. “Detecting Population III Stars through Tidal Disruption Events in the Era of JWST and Roman.” arxiv preprint arXiv:2401.12752 (2024).

The post Nancy Grace Roman Could Find the First Stars in the Universe appeared first on Universe Today.

We live in an age of renewed space exploration, colloquially known as Space Age 2.0. Unlike the previous one, this new space age is characterized by inter-agency cooperation and collaboration between space agencies and the commercial space industry (aka. NewSpace). In addition to sending crews back to the Moon and onto Mars, a major objective of the current space age is the commercialization of Low Earth Orbit (LEO). That means large constellations of satellites, debris mitigation, and plenty of commercial space stations.

To accommodate this commercial presence in LEO, Sierra Space has developed the Large Integrated Flexible Environment (LIFE) habitat, an inflatable module that can be integrated into future space stations. As part of the Commercial Low Earth Orbit Development Program, NASA, Sierra Space, and ILC Dover (the Delaware-based engineering manufacturing company) recently conducted a full-scale burst pressure test of their LIFE habitat. The test occurred at NASA’s Marshall Space Flight Center in Huntsville, Alabama, and was caught on video (see below).

Commercial space has become one of the fastest-growing businesses on Earth. In the past decade, the space economy has expanded by over 60% and is currently valued at around $400 billion. This is expected to grow considerably in the coming years as launch services increase, small satellites (CubeSats) become more affordable, and orbital stations are built. As the International Space Station (ISS) nears retirement, these commercial stations will provide opportunities for research and development, orbital manufacturing, and space tourism.

Sierra Space, the developer of the Dream Chaser reusable spaceplane, has demonstrated its commitment to the commercialization of LEO and the NewSpace economy. The first iteration of their inflatable habitat, LIFE 1.0, measures 6 meters (~20 feet) long and 9 meters (~30 feet) in diameter and can be launched using conventional rockets and inflates once in orbit. With a volume of 285 cubic meters (over 10,000 ft3), it can accommodate four astronauts, with additional room for science experiments, exercise equipment, and Sierra Space’s Astro Garden® plant-growing system.

The purpose of a burst pressure test is to gauge the structural tolerances of a component, be it a fuel tank or an inflatable module. The data gained from this test will assist engineers in simulating how the module will fare in the vacuum of space. Once development and testing are complete, the module will be used on commercial space stations like Orbital Reef, a collaborative effort between Blue Origin and Sierra Space. Future versions, like Life 2.0 and 3.0, will offer additional volume and be able to accommodate larger crews and more science operations.

According to their National Strategic Plan (released in 2022), one of NASA’s strategic goals is to develop a human spaceflight economy in collaboration with the NewSpace industry. In 2021, as part of a Commercial LEO Destinations (CLDs) project, NASA Space Act Agreements with three companies to design commercial space stations. This includes the Orbital Reef proposed by Blue Origin and Sierra Space, the Starlab space station by Nanoracks LLC, Voyager Space, Lockheed Martin, and Northrop Grumman’s free flyer commercial space station.

Starlab, from Nanoracks, Voyager Space, and Lockheed Martin – a continuously crewed, free-flying commercial space station in low-Earth Orbit. Credits: NanoRacks/Lockheed Martin/Voyager Space

As per NASA’s plan, creating a human spaceflight economy will ensure continued research and development in space while “allowing NASA to focus Government resources on the challenges of deep space exploration through Artemis.” Another goal is to maintain the legacy of the ISS long past its retirement:

“Since its inception, industry, academia, and our international partners have used the International Space Station (ISS) as a testbed for research and the development and maturation of state-of-the-art systems that increase access to space. NASA is supporting new space stations from which we and other customers can purchase services and stimulate the growth of commercial human spaceflight activities. As commercial LEO destinations become available, we intend to implement an orderly transition from current ISS operations to these new commercial destinations.”

Further Reading: Sierra Space

The post Watch a House-Sized Space Habitat (Intentionally) Burst appeared first on Universe Today.

Although our Moon formed 4.5 billion years ago, it’s still evolving. The interior continues to cool and its orbit is slowly changing. As a result, the Moon has lost 150 feet of its circumference. That shrinkage contributes to near-constant moonquakes, and those trigger landslides and other surface changes. The Moon is currently uninhabited, but all that activity threatens future Artemis landing sites and missions at the South Pole.

In a recent paper, planetary scientists point out that the potential of strong seismic events from active thrust faults should be a top consideration when NASA and other agencies are planning permanent outposts on the Moon. This is particularly true as the Artemis mission planners plot exploration of the South Pole. “Our modeling suggests that shallow moonquakes capable of producing strong ground shaking in the south polar region are possible from slip events on existing faults or the formation of new thrust faults,” said the study’s lead author Thomas R. Watters, a senior scientist emeritus in the National Air and Space Museum’s Center for Earth and Planetary Studies. “The global distribution of young thrust faults, their potential to be active, and the potential to form new thrust faults from ongoing global contraction should be considered when planning the location and stability of permanent outposts on the Moon.”

The Moon is particularly vulnerable to the large-scale effects of moonquakes. That’s because its surface is very brittle and easily broken up during a quake. One of the strongest quakes in lunar history occurred in the 1970s and lasted for hours. Such a lengthy event does quite a bit of damage to the lunar surface. So, even a light moonquake could cause significant damage via landslides.

Our Shaky, Shrinking Moon

Moonquakes generally happen within a hundred miles or so of the lunar surface. On Earth, that might result in a fairly mild quake. But, since the Moon’s surface is so brittle, the effects of those “shakes” are much more noticeable. According to Nicholas Schmerr, a co-author of the paper and an associate professor of geology at the University of Maryland, this means that shallow moonquakes can devastate hypothetical human settlements on the Moon.

“You can think of the Moon’s surface as being dry, grounded gravel and dust,” he said. “Over billions of years, the surface has been hit by asteroids and comets, with the resulting angular fragments constantly getting ejected from the impacts,” Schmerr explained. “As a result, the reworked surface material can be micron-sized to boulder-sized, but all very loosely consolidated. Loose sediments make it very possible for shaking and landslides to occur.”

An LROC NAC mosaic of the Wiechert cluster of lobate scarps in Moon’s south pole region, left pointing arrows). A scarp crosscuts a small (?1 km) degraded crater (right-pointing arrow).

Quakes affect every part of the lunar surface. Global compressional stresses deform the surface, forcing splits and cracks to occur. These scarps—steep slopes and cliffs—exist everywhere there. In their paper, the team suggests that many are close to the epicenters of geologically recent quakes. And the regions where they occurred could still be active today. That includes the lunar South Pole.

Risks to Artemis

The team led by Watters examined data and images of the lunar South Pole and linked faults there to a major moonquake in the 1970s. The region is filled with scarps, which are prime evidence for moonquakes. Although they conclude that some regions in the area are probably safe enough for the Artemis missions, others are not. The team’s computer models show that the most dangerous areas are vulnerable to landslides triggered by seismic shaking. They continue to map the Moon and track its quakes to identify the riskiest areas for Artemis astronauts to land.

A mosaic of Shackleton Crater at the Moon’s south pole region. It shows a portion of an interior wall and floor, with arrows pointing to boulder falls likely created during seismic shaking during a moonquake. Image courtesy: NASA/KARI/ASU

That mission could take place by the end of the decade, when NASA hopes to establish long-term habitations for research and exploration. Schmerr points out that the risks to safety from even the slightest quakes can’t be overestimated. “As we get closer to the crewed Artemis mission’s launch date, it’s important to keep our astronauts, our equipment, and infrastructure as safe as possible,” Schmerr said. “This work is helping us prepare for what awaits us on the moon—whether that’s engineering structures that can better withstand lunar seismic activity or protecting people from really dangerous zones.”

The Artemis missions essentially mark NASA’s return to human exploration of the Moon. The idea is to collaborate with both commercial partners and international agencies to make this happen. Teams of lunar astronauts will establish an Artemis Base camp, and depend on a lunar gateway to connect the mission to Earth. Eventually, what they learn there will inform the first human missions to Mars.

For More Information

The Moon is Shrinking, Causing Landslides and Instability in Lunar South Pole
Tectonics and Seismicity of the Lunar South Polar Region
Artemis

The post The Moon is Still Shrinking, Explaining Why it Still Has Landslides appeared first on Universe Today.

A rubbery patch studded with suction cups that imitate the suckers on octopus limbs can make drugs penetrate the skin without breaking it or causing irritation

TOI-1136, a dwarf star located more than 270 light years from Earth, is host to six confirmed exoplanets and a seventh as yet unconfirmed candidate. The system has provided a rich source of information on planet formation and evolution in a young solar system. Researchers used a variety of tools to compile radial velocity and transit timing variation readings to derive highly precise measurements of the exoplants' masses, orbital information and atmospheres.

Scientists undertook a study of dragonfly wings in order to better understand the relationship between a corrugated wing structure and vortex motions. They discovered that corrugated wings exhibit larger lift than flat wings.

A new study found that graphene derived from metallurgical coke, a coal-based product, through flash Joule heating could serve not only as a reinforcing additive in cement but also as a replacement for sand in concrete.

Physicists propose a novel way to create photoconductive circuits, where the circuit is directly patterned onto a glass surface with femtosecond laser light. The new technology may one day be useful for harvesting energy, while remaining transparent to light and using a single material.

Physicists propose a novel way to create photoconductive circuits, where the circuit is directly patterned onto a glass surface with femtosecond laser light. The new technology may one day be useful for harvesting energy, while remaining transparent to light and using a single material.

Physicists discovered stars near the edge of the Milky Way travel more slowly than those closer to its center -- a surprise suggesting our galaxy's gravitational core may have less dark matter than previously thought.

Compared to robots, human bodies are flexible, capable of fine movements, and can convert energy efficiently into movement. Drawing inspiration from human gait, researchers from Japan crafted a two-legged biohybrid robot by combining muscle tissues and artificial materials. This method allows the robot to walk and pivot.

Compared to robots, human bodies are flexible, capable of fine movements, and can convert energy efficiently into movement. Drawing inspiration from human gait, researchers from Japan crafted a two-legged biohybrid robot by combining muscle tissues and artificial materials. This method allows the robot to walk and pivot.

A study reconstructing the climate of Italy during the Roman Empire based on marine sediments shows that three pandemics coincided with cooler, drier conditions

If you go back to my posts from before October 7, you’ll see that I have always favored a two-state solution to resolve the enmity between Palestine and Israel, although I knew that such a solution had been proposed several times by Israel—and rejected by the Palestinians.  Now, however, it’s not a viable solution to the problem, despite many touting it as an exigent and workable solution.

That suggestion is, I think, misguided right now, though perhaps some day it might work.  On the Palestinian side, it’s clear that they want a one-state solution (“from the river to the sea”), and that one state will be Palestinian. What would happen to the Jews in such a solution? Well, they can all be deported (I think Bill Maher joking suggested using a “Jew Haul” system), but most people think that a one-state solution that contains both Jews and Palestinians would inevitably lead to a massacre of Jews as well as the extinction of Israel.  I doubt that anybody in Israel except for a few far-left nutjobs now favor a one-state solution.

On the Israeli side, while many once favored a two state solution, they no longer do. It’s simply unthinkable, after October 7, to imagine a Palestinian state rubbing up against a Jewish one.  The fear, of course, is terrorism. If Hamas ran that state, forgetaboutit. They’ve already vowed to repeat the October 7 massacre over and over again.  And the Palestinian Authority, otherwise known as the corrupt and terrorist-promoting government of Mahmoud Abbas, is not a viable negotiating partner (neither is Netanyahu, as he isn’t trusted by many Israelis but also shares Israel’s correct assessment that a two-state solution is not worth considering now).  First, the war has to end and then—and this is the tough part—there have to be honest brokers and negotiators on both sides. Given the Palestinians’ complete aversion to a two-state solution, though, I simply can’t imagine it happening. What Palestinian government will guarantee to live peacefully beside Israel with no more terrorism, especially since Palestinian children are taught to hate Jews and love martyrdom almost from birth?

I wrote the above because the article below, from Tablet, will make people see why a two-state solution is presently inviable.  For a long time I and others have thought there were two groups of Palestinians: the terrorists sworn to extirpate Israel, and the “regular” people who just wanted to live their lives in peace. And I assumed the latter group was far more numerous than the former. But this is likely an illusion given the polls showing an increase in support for Hamas and a decrease in support for the Palestinian authority and Abass (see here and here). Those same polls show that many Palestinians admire the October 7 attacks as a sign of resistance, not an episode of brutal butchery.

And it’s not just Palestinians: it’s Arab-world wide. Here’s the results of a poll I posted about recently, one taken by the The Arab Center for Research and Policy Studies, and it shows widespread support for Hamas’s Oct. 7 attack in every country in the Arab world (Egypt and Iraq show lower but still substantial support:

Given all this, who could possibly confect a two-state solution that would work? Certainly not one with Hamas involved. My view now is that Hamas still should be defeated and dismantled, but what happens next is shrouded in mystery. But any solution has to allow Israel to be free from terrorism.

Right now I agree with Douglas Murray on the two-state solution below (I don’t agree on anything pro-Trump said, especially by the moderator!) I’d forgotten that the Palestinian Authority had agreed to pay the families and perpetrators of Hamas’s October 7 attack.

The article below is infinitely depressing because it shows that not just a small group of Palestinian terrorists participated in the October 7 massacre. Instead, many, many civilians, including Palestinian children and even old men on crutches.  The conclusion adumbrated by Jews who were interviewed—many of them Jews who used to work for peace with Palestine—is that Palestine is riddled with people who approve of the massacre and would participate in another one if given a chance.  When the title says that October 7 is a “pogrom”, they are using this definition from Wikipedia: it’s not really a genocide, but a mass attack on one group, not necessarily, I think, with intent to wipe out a whole ethnic group—which is of course what Hamas intends in the long run:

A pogrom is a violent riot incited with the aim of massacring or expelling an ethnic or religious group, particularly Jews.[1] The term entered the English language from Russian to describe 19th- and 20th-century attacks on Jews in the Russian Empire (mostly within the Pale of Settlement).

This article is one in a series from Tablet, “Hamas’s war on Israel“.  Click below to read. It’s not super-long, and it’s very enlightening.

I’ll just give quotes. First, the overall take. (Quotes are indented; my own remarks are flush left.)

Survivors’ accounts, video evidence, and the interrogation recordings of apprehended Palestinians paint a damning picture of the complicity of Gazan civilians both in the Oct. 7 attack, in which more than 1,200 people were murdered and 240 people were abducted to Gaza, and its aftermath. It is one that has sparked a debate in Israel that challenges the inclination to draw distinctions between ordinary Palestinian civilians of Gaza—often referred to in Israel as bilti me’uravim (uninvolved)—and their terror leaders. For many, Oct. 7 reeked of something that Jews have been familiar with for centuries; a phenomenon where not just a vanguard, but a society at large participates in the ritual slaughter of Jews.

Around 700 Palestinians stormed Barad’s kibbutz of Nir Oz—less than a five-minute drive from Gaza—that day, CCTV footage shows. The overwhelming majority of those, estimated by Eran Smilansky, a member of the kibbutz’s security squad, to be around 550, were civilians. They were largely unarmed and not in uniform. Some of those civilians carried out wholesale acts of terror themselves, including rape and abduction—and in some cases, the eventual sale of hostages to Hamas—while others abetted the terrorists. Others still simply took advantage of the porous border to loot Israeli homes and farms, including stealing hundreds of thousands of shekels in agricultural equipment.

Similar scenes played out in several of the more than 20 brutalized Israeli communities. In one video that has become emblematic of the debate around the “uninvolved,” an elderly Palestinian man with walking sticks is seen hobbling at an impressive clip along with the rest of the mob through the breached gate of Be’eri.

Differentiating between terrorists and civilians is tricky, particularly since Hamas terrorists often wear civilian clothing, a tactic evident in the ongoing war in Gaza. However, other indicators help make this distinction, such as the absence of weapons and the fact that many were filmed crossing the border barefoot or even on horseback. Even senior Hamas official Mousa Abu Marzouk readily admitted that Gaza civilians had taken part in the Oct. 7 atrocities.

One video shows a group of men in civilian clothing beating a soldier while a separate image shows another group of what appears to be civilian men celebrating atop the smoking husk of a burned-out tank. In the infamous 47-minute terror reel of the Oct. 7 atrocities, Palestinians in civilian clothing are seen beating elderly hostages with sticks. Another repeatedly screams “Allahu akbar!” as he decapitates a Thai farm worker with a garden tool.

Barad’s speed camera in Nir Oz includes images of a Palestinian girl riding a stolen bike. In another, a Palestinian woman is seen pointing out Barad’s neighbor’s home to a uniformed terrorist. An image captured later shows a resident of that home being hoisted onto a motorcycle to be taken into Gaza.

But it’s the testimonies of the survivors that provide the clearest evidence that Oct. 7 was not just a terrorist attack, but a pogrom.

Two aspects of the narrative are surprising and saddening:  Palestinian workers at the kibbutz—as well as the 18,000 Palestinians per day who cross the border to work in the “apartheid state” of Israel—apparently participated in the massacre, giving Hamas valuable information about the layout, sites of electrical panels, and so on. Further, the southern border of Israel harbored many Israelis who were there to work for peace: to create some kind of harmony, or even two harmonious states, between Israel and Palestine. And yet these peace activists were murdered just as brutally as anyone else.  Some quotes:

 

Then there are the Gazans who worked at the kibbutzim. Yohanan’s husband, a farmer, is one of many people in the Gaza periphery communities who hired Palestinian workers from Gaza. Like many others I spoke to, Yohanan believed that the terrorists were acting on inside knowledge obtained by those Gazan workers. Israel had gradually raised the number of work permits in the months leading up to Oct. 7 with an estimated 18,500 Gazans working in Israel before the onslaught. The thinking behind the policy was that economic incentives to the residents of the Strip would sustain the fragile peace. Hanan Dann, from Kfar Aza, told me that he was “glad that workers from Gaza were coming to Israel to have jobs and meet Israelis, to see that we’re not all devils.”

In several of the devastated communities, detailed maps were found on the bodies of dead terrorists, maps that residents say could have only been drawn up by people with intimate knowledge of the area. Gazan workers relayed an extensive range of information to Hamas that enabled the terror group to plan its attack with extraordinary meticulousness, including the identities and residences of security heads, the locations of electric boards and communications systems and how to disable them.

The workers’ betrayal left an indelible mark on the surviving kibbutzniks, leading many to reexamine previously held beliefs about their Palestinian neighbors. Nir Oz, like many of the other ravaged kibbutzim in the area, was home to scores of peace activists, many of whom volunteered for a program known as Road to Recovery, driving sick Gazans to Israeli hospitals for treatment. Many now believe that while there are Gazans who want to live in peace, they do not represent the majority; or, as one survivor summed it up to AFP, “there are more who don’t want us alive.”

Irit Lahav, whose parents were from Nir Oz’s founding members, described the community as a “peace lovers’” kibbutz. “It broke my heart. How can we ever get over this sense of betrayal?” Lahav, who shuttled Palestinian cancer patients several hours from the border with Gaza to their treatments in central Israel, told me. “The Palestinian public simply hates us.”

And this is the conclusion of one disaffected Israeli:

Not everyone, however, was surprised by the involvement of Gazan civilians. “I don’t differentiate between them and Hamas,” Nir Shani told me. “Let me know of one Palestinian in Gaza who tried to save a Jew and maybe I’ll change my mind.”

That’s a good question.

Here’s a peace worker betrayed:

Batya Holin is a photographer and peace activist from Kfar Aza, which alongside Nir Oz and Be’eri, was one of the heaviest-hit communities. Holin had developed a friendship with a Gazan photographer, Mahmoud, with whom she arranged a joint exhibit last year of photos of her kibbutz and his village in the Gaza Strip. On the morning of Oct. 7, Mahmoud called and interrogated Holin, asking her how many soldiers were in her vicinity. That was when Holin realized that Mahmoud had given the photos of her village to Hamas. “Whoever says there are people there who are uninvolved, here is the proof,” she told Israel’s Channel 13 News. “They are all involved. They are all Hamas.”

There’s more documentation of civilian involvement, including not just the participation of civilians in the attack itself but also their approbation of the hostages and bodies of Israelis brought back, and, finally, their involvement in other ways. Here’s an example of the last two:

In one viral video, the near-naked and bloodied body of Shani Louk, an Israeli German who was abducted from the Nova music festival but who was later declared dead, is seen being paraded through the streets of Gaza in the back of a pickup truck. Hordes of Palestinian civilians are cheering, spitting and slapping Louk’s deformed figure while chanting “Allahu akbar.” The last tranche of hostages to be released in November’s truce saw crowds of Palestinians line the streets, jeering as the Red Cross ambulances passed by. The aunt of released hostage Eitan Yahalomi said that after the arrival of her 12-year-old nephew into Gaza, “all the civilians, everyone, beat him.”

IDF Sgt. Adir Tahar was murdered and decapitated during the invasion while manning a post near the Erez border crossing. His father, David, was forced to bury his son’s body without his head. An interrogation of two Palestinians by Israel’s Shin Bet security agency revealed that the remains of the head—which had been mutilated until it barely resembled a human skull—were kept in the freezer of an ice cream store in Gaza. One of the men had tried to sell the head for $10,000. The man in question was a Palestinian civilian and not a Hamas operative, Tahar told me. The Shin Bet did not respond to a request for confirmation in time for publication.

The conclusions: the Israelis, after hearing things like this, have become wary of not just Hamas, but of most Palestinians, who, they think are eager to kill them—civilians that could become terrorists or could aid terrorists. And this has pushed the chance for postwar peace to near zero:

 

“If we previously believed that there was a chance for peace, we’ve lost all faith in these people, especially after we were there and among the population,” Goldstein-Almog added.

 

A tiny, biohybrid robot moves by contracting lab-grown muscle tissue in its legs – but it needs help to stand up in a water tank and it tops out at just 5.4 millimetres per minute

Engineered cells that make the substances they need to grow could dramatically reduce the cost of cultivating lab-grown meat

Engineered cells that make the substances they need to grow could dramatically reduce the cost of cultivating lab-grown meat

As April’s ‘Great North American Eclipse’ nears, here’s a look at eclipses in time and space.

It comes around every total solar eclipse, and I fully expect to hear it trotted out once again this year, leading up to the Great North American eclipse on April 8th, 2024.

It’s often repeated (usually around the time leading up to a total solar eclipse) that the syzygy of the Earth, Moon and Sun is special, allowing totality to occur. To be sure, eclipses are extraordinary and spectacular events, and standing in the shadow of the Moon during totality is a spectacle that shouldn’t be missed.

But just how rare are the circumstances we witness on Earth during totality across time and space?

The path of totality across North America on April 8th, 2024. Credit: Michael Zeiler/The Great American Eclipse How Rare are Eclipses?

The Moon’s orbit intersects the ecliptic at two points, known as its ascending and descending nodes. We see lunar and solar eclipses on Earth when these nodes line up with the Sun (during a solar eclipse) or the Earth’s shadow (during a lunar eclipse). The Moon’s path is tilted just over 5 degrees versus the ecliptic plane. This means that most of the time, the Moon misses the Sun, and the Earth’s shadow. If it wasn’t tilted, an even more unique situation would occur. In this case, we’d see two eclipses (one lunar and one solar) occurring every synodic period or roughly just under once a month. As it is, eclipses worldwide happen in seasons or about twice a year as the nodes line up, with a solar and lunar eclipse about two weeks apart.

How a totality occurs. Credit: NASA

The precision-looking fit of the Moon over the Sun seen during totality is due to geometry. The Sun is about 400 times farther away from the Earth than the Moon, and 400 times as large in terms of physical diameter. But this is only approximate, and only true for our current epoch.

Geometry for lunar and solar eclipses, with the true scale of the Moon’s umbra during totality (bottom). From The Universe Today’s Ultimate Guide to Viewing the Cosmos. A Receding Moon

In fact, we know from the retro-reflectors placed on the Moon by Apollo astronauts that the Moon is moving away from us at 3.8 centimeters per year. About 600 million years from now, the last total solar eclipse will occur as seen from the Earth. Likewise, about a billion years in the past, the first brief annular solar eclipse must have occurred.

The apparent size of the Sun and Moon also vary slightly from one eclipse the the next. This ranges around half a degree (30 arcminutes) by few arcminutes (‘). This occurs as the Earth travels from perihelion to aphelion, and the Moon travels from perigee to apogee. When the Moon is too small to cover the Sun, a ‘ring of fire’ annular solar eclipse occurs.

The value difference for the apparent size of the Sun ranges from 31.6′ to 32.6′, and the Moon is 29.3′ to 34.1′. During the April 8th total solar eclipse, the Sun will be an apparent 31′ 57″ across. The Moon will be slightly larger, at 33′ 37″ across. This will yield a generous maximum totality of 4 minutes and 28 seconds in duration, as seen from near Nazas, Mexico .

A Fortunate Epoch

Even now in our current 5,000-year epoch, annulars are already more common, at 33.2% to 26.7% versus totals. The remainder are partials and rare hybrid annular-total eclipses.

“I found that whenever I use the phrase ‘cosmic coincidence’ to describe our current good fortune in the distance/diameter ratios favorable for a tight occultation of the Moon and Sun, almost predictably some of the responses will be ‘there are no coincidences,’ or ‘divine provenance,'” Eclipse chaser and cartographer Michael Zeiler told Universe Today. “I respond that often coincidences are true! We are simply lucky to live within the evolution of our solar system to witness total solar eclipses.”

Looking Out Across the Solar System

To be sure, solar eclipses do occur throughout the solar system. It’s all a matter of perspective, and literally knowing where and when to stand. New Horizons saw the Sun pass behind Pluto in 2015 (a sight no human eye has ever witnessed). Rovers on Mars have caught strange potato-shaped annular eclipses (or more properly, transits) courtesy of Deimos and Phobos.

Deimos transits the Sun, as seen by NASA’s Perseverance Rover of Sol 1037 (January 20th, 2024). Credit: NASA/JPL Image processing: Simeon Schmaub

These robotic observations of the Martian moons aren’t just pretty pictures. They also also researchers to refine and pin down the exact orbits of both Phobos and Deimos. This is handy, as Japans Martian Moons Explorer is headed to the pair in 2026.

What’s more, Phobos is doomed to crash into Mars millions of years from now… at some far off date, it will briefly be close enough to totally eclipse the Sun as seen from the Martian surface. If humans are on Mars on November 10th, 2084, they can witness an uber-rare, transit featuring Phobos, the Earth and the Moon.

Eclipses and the Curious Case of the Jovian Moons

Of course, none of these are are precise fits in terms of the eclipsing body versus the Sun. There is, however, another place in the solar system you could stand on a solid surface and witness totality similar to what’s seen on Earth. (Be sure to pack your space suit). Jupiter’s major moons produce eclipses very analogous to those seen on Earth as they pass one in front of the other. This happens in cycles that occur during what’s known as mutual eclipse-transit season. This happens when the major Galilean moons of Io, Europa, Ganymede and Callisto mingle as seen from our perspective.

Europa as seen from the surface of Callisto is a particularly good baseline ‘fit’. Europa is about 1/450th the size of the Sun, which is also 450 times farther away at certain points along its orbital path… not all that different than eclipse circumstances here on Earth. These events are faster, lasting only a few dozen seconds at most. Mutual transit-eclipse season occurs twice every Jovian orbit, or every six years. The next cycle resumes in 2026.

Io casts its shadow on Ganymede in 2009. Image credit: Christopher Go. A Twice a Decade Transit Season

We noticed this similarities of Jovian versus terrestrial eclipses while writing an article on mutual eclipse season in 2015. To be sure, eclipse seasons on the Earth tend to be biannual, while seasons in the Jovian system occur less frequently, about twice a decade. More distant moons may see similar celestial sights, but for now, my future plans for building an eclipse viewing hotel and resort are pegged for the surface of Callisto.

Bill Kramer also did a fascinating look at eclipses throughout the solar system from a few years back, posted on his Eclipse-Chasers website.

The Hunt for ‘Exo-Eclipses’

So, what does this all say for eclipses beyond our solar system? Well, as of writing this, there are 5,506 exoplanets known… but claims of any ‘exomoons’ orbiting them remain controversial. Even the best known cases—such as the contentious recent Kepler-1513 b exomoon claim—still have very wide distance and diameter perimeters to say if good-fit eclipses are possible. Still, as the menagerie of extra-solar worlds grow and good exomoon candidates are found, we might yet be able to say with some authority just how common ‘exo-eclipses’ are very soon.

Perhaps, human astronauts will one day witness these far-flung eclipses. Imagine standing on the Earthward face of the Moon during a total lunar eclipse, and witnessing ‘a thousand sunsets’ as the Earth eclipses the Sun. For now, I’d wager that ideal tight-fit eclipses aren’t all that uncommon when you take into account the vast expanse of time and space… but totality over an expanse where life has evolved to enjoy it might be rare indeed.

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All modern life shares a robust, hardy, efficient system of intertwined chemicals that propagate themselves. This system must have emerged from a simpler, less efficient, more delicate one. But what was that system, and why did it appear on, of all places, planet Earth?

This is the central question of abiogenesis, the generation of life from not-life. We do not yet have an answer to that question, but we do have a collection of curious clues and brilliant hypotheses that might lead us in the right direction.

First, the chemistry. All proteins on Earth are made from just 22 amino acids. Those amino acids require abundant amounts of organic molecules – the most basic building blocks of life. Astronomers have detected organic molecules, and even some amino acids, scattered throughout space, from the depths of interstellar gas clouds to the fragile meteoroids that wander the solar system. So it’s natural to assume that our planet, as it coalesced from the maelstrom that surrounded our infant Sun, was born with the right ingredients…but surely they couldn’t survive the initial formation of our planet, when it was still molten from the countless collisions that lead to its development.

Instead, these organic compounds must have been delivered to us well after the planet cooled and solidified. Astronomers believe that the first few million years in the solar system was a quite unfriendly time. Even after the protoplanetary disk around the Sun evaporated and the eight major planets of the system emerged victorious over their rivals, fragments and debris still littered the orbital lanes. Impact after impact struck each of the planets, with new rounds triggered by gravitational rearrangements of the giant outer worlds as they settled into stable, permanent configurations.

We still see the scars of that youthful violence today, visible on the sterile vacuum surfaces of the Moon and Mercury.

But in that violence came a chance for life. Fresh water, delivered by countless cometary impacts, replenished what the Earth lost during its molten state. And with that water, organic compounds rained onto the surface. Here too we see yet another delicate balancing act. If the Earth had been struck too few times, we might not have been wealthy enough in molecular resources to begin the ascent to life. If too many had come, however, the persistent heat of the impacts would have boiled our oceans and sent any nascent life scattering into interplanetary space.

We were lucky. Somewhere life gained a foothold. The earliest undisputed fossil evidence for life sets the clock as early as 3.5 billion years ago. More speculative evidence – again, this work becomes exceedingly difficult the farther back into the past we peer, because the earliest life was not much different than the non-living chemical reactions that preceded it, so it’s difficult to tell if some molecular imprint in a rock is the fossil of a living creature or merely some manifestation of exotic chemistry, and if there’s even a difference between them – suggests that life started as early as 4.5 billion years ago. That alone is surprising, given the hellish conditions our planet was experiencing at the time, with some scientists arguing that our world wasn’t even habitable until some 500 million years later.

But somewhere, in some quiet place, the magic happened. A chance group of molecules and chemical reactions began storing information, began self-replicating, and began catalyzing reactions. Some biologists suspect that it was deep-sea hydrothermal vents, which spew organic-rich molecules into their surroundings. Or perhaps it was in tidal pools, which provided a natural rhythm that would turn into the cycles of life. Or maybe hot springs, or even underground.

It may have happened more than once and in more than one way, but it appears from all available evidence that as soon as life could arise, it did arise.

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