Rocks In Space

 You have probably seen a shooting star while outside at night. Maybe you have also witnessed a meteor shower when numerous shooting stars occur over the course of the night. They represent a tiny piece of our solar system falling to Earth. Sometimes, many meteors can be seen over the course of a few hours. We call these meteor showers.

 Perseid meteor shower which peaks in Mid-August. Credit NASA/Preston Syches

Our solar system consists of eight planets. Well, some people, myself included, believe that Pluto should still be considered a planet, and there is evidence that another one orbits far from the sun but has yet to be discovered. Along with those planets, there are five objects that astronomers refer to as “dwarf planets” orbiting the sun. That’s what Pluto was demoted to in 2006.

Our sun is also orbited by thousands of asteroids, smaller rocky objects left over from the formation of the planets. Many of these orbit between Mars and Jupiter in a region called the Asteroid Belt. In the region beyond Neptune lies an area called the Kuiper Belt, a flattened disc   of millions of comets, objects containing mostly frozen gases along with a bit of rocky material. Even more comets exist in a vast shell surrounding our solar system.

The asteroids in the asteroid belt occasionally collide, creating a large number of smaller bits of rock, which astronomers call meteoroids. Being so small, they are easily affected by the gravity of other bodies orbiting the sun and scatter throughout the inner solar system.

Artist's view of the asteroid belt. Credit NASA

If one comes close to our planet, Earth’s gravity reels it in. These meteoroids enter our atmosphere at tremendous speeds, often exceeding 25,000 miles per hour. At such speeds, friction with our air creates so much heat that the air itself begins to glow. That glowing streak of light is known as a meteor or a shooting star. The tiny bit of rock itself is far too small to be seen, typically being not much larger than a grape.

The heat created by the meteoroid’s passage through our atmosphere will usually disintegrate it into fine dust. If the meteoroid creating the shooting star is large enough to survive to the ground, we call it a meteorite. Scientists estimate that a few hundred tons of meteoritic material fall to Earth each day, much of it in the form of very fine dust from disintegrated meteoroids. Many larger pieces fall as meteorites. These are highly prized by scientists because they help us understand how our solar system formed. Collectors pay for meteorites. The rarest meteorites come from the Moon and Mars. The largest known Martian meteorite sold for 5.3 million dollars.

How does a hunk of Mars fall to Earth? Asteroids occasionally strike Mars. Due to its smaller gravity, fragments can be blasted into space. Rarely, such a piece of Mars eventually falls to Earth. There are only some 400 known Martian meteorites found on Earth.

     Meteorites aren’t the only things that fall from the sky. Along with mundane weather phenomena like rain, hail, sleet, and snow, some surprising things have fallen to earth. Large numbers of live and dead animals occasionally fall. People have found golf balls, coins, and even sugar crystals that fell from the sky. Some objects, like meteorites, fall all the way from space. You can learn about these and many more of the strange objects that have fallen to the ground in my book “When the Sky Falls, Duck.” This book won a recent Non-Fiction Book of the Year Award. It is available from Barnes and Noble’s online store at BN.com.

 

    Each month, I write an astronomy-related column piece for the Oklahoman newspaper. After it is published there, I post that same column to my blog page.

    This is reprinted with permission from the Oklahoman and www.Oklahoman.com.

Weird Rocks on Mars

 Perhaps you have seen videos or pictures of rocks very carefully stacked as an artistic work. They may even look impossibly balanced. 

Balanced Rocks. Wikipedia.

    Or you may have seen so-called balancing rocks, with one huge boulder precariously sitting on a tiny point on top of another large boulder. These terrestrial balancing boulders weren’t created by humans, but rather by wind and water erosion.

Balancing rocks formed by erosion. Nevada Traveler

Scientists studying the images and data sent back by the Perseverance rover on Mars found an unusual sight. It appears to be three or four rocks neatly stacked one on top of the other. It rather resembles a hamburger with an oversized patty or an undersized bun. The patty in the middle looks as if it broke because the bun was too small. The rocks fit together so perfectly that they look as if they were stacked by human hands. Scientists attribute the stacked appearance to wind erosion of a single rock. Some say it looks more like water erosion, but there hasn’t been any surface water on Mars for perhaps 3 billion years.

Staxcked rocks on Mars. NASA/JPL/Cal Tech

This find by Perseverance isn’t the only weird rock discovered on the surface of Mars. Perseverance photographed a rock with stripes or striations on it. It looks to the scientists studying the images and data from the rover to be volcanic in origin. It appears to have fallen from a layer of similar rock farther up the slopes of Jezero crater that Perseverance has been exploring since it landed. Athanasios Klidaras, a PhD student in planetary science at Purdue University, wrote in a statement on NASA's Science website, "Our knowledge of its chemical composition is limited, but early interpretations are that igneous and/or metamorphic processes could have created its stripes."

Stripped rock on Mars. NASA/JPL/Cal Tech

One of the stranger rocks Perseverance imaged the researchers nicknamed "St. Pauls Bay." It is covered with hundreds of millimeter-sized, dark grey spheres. Some of them have tiny pinholes in them. Scientists believe these spheres to be concretions formed by the interaction of groundwater circulating through pores in the rock. It is also possible they were formed by volcanic activity. "Each of these formation mechanisms would have vastly different implications for the evolution of these rocks, so the team is working hard to determine their context and origin," the mission team said in the statement. "Placing these features in geologic context will be critical for understanding their origin and determining their significance for the geological history of the Jezero crater rim and beyond."

Studded rock on Mars. NASA/JPL/Cal Tech

While Perseverance’s main job is to look for evidence of past life on Mars, which it has yet to find, it is finding that the environment was once, long ago, conducive to life. It may yet find fossilized bacterial remains like those we have found on our planet.

 

Each month, I write an astronomy-related column piece for the Oklahoman newspaper. After it is published there, I post that same column to my blog page.

This is reprinted with permission from the Oklahoman and www.Oklahoman.com.

Where Will the First Space Baby Be Born?

 Since the International Space Station, ISS, became operational, the length of astronaut stays in the weightlessness of space have increased from days or weeks to months and years. The crews now regularly consist of both men and women. Only one married couple, Mark Lee and Jen Davis, has been on a space mission together. Their trip was on board the now-decommissioned Space Shuttle, which offers no privacy. Although NASA claims that no astronauts have had sex off Earth, that will change as NASA and other space agencies plan for eventual permanently manned stations in orbit around or on the surface of the Moon. Eventually, NASA plans to send crews to Mars and, in the more distant future, have permanent colonies on Mars. A round trip to Mars, even if they don’t land there to study the planet, will take as much as three years.

Artist conception of a Martian colony. Wikimedia Commons

A senior NASA research scientist, Fathi Karouia, co-wrote a paper along with eight other experts in reproductive medicine, aerospace health, and bioethics. They took as their goal to study and identify any risks and define the gaps in research and governance of conception in space. "As human presence in space expands, reproductive health can no longer remain a policy blind spot," Karouia said in a statement. "International collaboration is urgently needed to close critical knowledge gaps and establish ethical guidelines that protect both professional and private astronauts, and ultimately safeguard humanity as we move toward a sustained presence beyond Earth."

Giles Palmer, a senior clinical embryologist at the International IVF Initiative who led the new study, said in the paper, "As human activity shifts from short missions to sustained presence beyond Earth, reproduction moves from abstract possibility to practical concern."

Limited laboratory experimentation and data on astronauts on longer ISS flights give scientists some worrisome details. They show us that weightlessness, radiation, altered circadian rhythms, psychological stress, and prolonged isolation all pose risks to the reproductive functions in both women and men.   

Several insects have been taken into space and allowed to breed. Findings of these experiments showed accelerated aging and immune system compromise, among other irregularities, but all were able to successfully breed. Follow-up studies of the offspring back on Earth haven’t been performed.

Certain physical peculiarities have been seen in astronauts. Those who stay in space for too long develop puffy heads and bird-like, thin legs. This occurs because the heart can more easily pump blood up to the head, so much so that their brains start to float and move around a bit. As their bodily fluids move toward the heads of astronauts, they can develop neuro-ocular syndrome. The optic nerve swells due to greater fluid pressure, causing the back of the eye to flatten. According to NASA, 70% of astronauts on the ISS experience some amount of swelling in the back of their eyes. This may cause blurry vision and the occasional headache. Glasses can help alleviate this. On Earth, your bones and muscles must constantly work to keep you upright against the pull of gravity. With a lack of gravity, that’s no longer necessary, and astronauts lose bone and muscle mass.

While all these effects eventually return to normal upon returning to Earth's normal gravity, the concern is how such issues might affect a fetus in the womb. A fetus conceived in space won’t have ever experienced “normal” body functions for the body to return to. How will such physical changes affect their development?

We will eventually go to the Moon and on to Mars. A trip to Mars will last longer than the gestation period of a human baby. It is possible that those children will never be able to come back home after growing up in such a different gravitational environment. They may end up becoming the first true Martians.

 

Each month, I write an astronomy-related column piece for the Oklahoman newspaper. After it is published there, I post that same column to my blog page.

This is reprinted with permission from the Oklahoman and www.Oklahoman.com.

Does Tryptophan in Turkey Make you Sleepy? Blame the Cosmos

After your Thanksgiving feast, did you crash? Many people do, and it has been blamed on tryptophan, an amino acid in turkey. It’s possible you have the cosmos to blame for that.

According to an internet search, “Tryptophan is an essential amino acid the body uses to make proteins, the neurotransmitter serotonin, and the sleep-related hormone melatonin. It is not produced by the body, so it must be obtained through diet from foods like turkey, chicken, nuts, and soy.” This, some people claim, is why you feel sleepy after a Thanksgiving meal that includes turkey.

Astrobiologists, specialists who seek evidence of life elsewhere, and biologists who study the origins of life on Earth suggest several ways life might have started here. One idea is known as panspermia. Panspermia says that life on Earth was seeded from space, most likely by organic molecules delivered to Earth via asteroids, comets, or meteorites, which carried these molecules.

Earth spacecraft have returned samples from two asteroids, Ryugu and Bennu. They have found 90 amino acids, including 14 of the 20 used by life on Earth. In addition, they have found all five of the bases, adenine, guanine, cytosine, thymine, and uracil, which make up our DNA.

The asteroid Bennu. Credit NAS/JPL/University of Arizona

One of the amino acids on asteroid Bennu was tryptophan. José Aponte is an astrochemist at NASA's Goddard Space Flight Center who coauthored a study on the sample returned from Bennu. On finding that sleep-inducing molecule on Bennu, he said, "Finding tryptophan in the Bennu asteroid is a big deal, because tryptophan is one of the more complex amino acids, and until now it had never been seen in any meteorite or space sample."

Many biologists and other scientists who study the formation of life on Earth believe that it rose independently here. But the delivery of important organic and other biologically important molecules to our planet from space must surely have played a role. Before you say life here didn’t come from the stars, remember that most of the molecules in our bodies were formed in stars, so we are literally star dust.

 

Each month, I write an astronomy-related column piece for the Oklahoman newspaper. After it is published there, I post that same column to my blog page.

This is reprinted with permission from the Oklahoman and www.Oklahoman.com.

Is a Primordial Black Hole Aiming at Us?

 Many mysteries about our universe haunt astronomers.  Among those, one of the most perplexing is what they call “dark matter.” By studying the gravitational interactions and motions of galaxies, astronomers learned that most of the matter in our universe, about 86%, is composed of stuff that has no connection to light. It doesn’t emit, reflect, or absorb any type of electromagnetic radiation, including light, hence the moniker dark matter.

Astronomers know it’s there. The evidence for it is overwhelming. Galaxies rotate so fast that they should fly apart unless there is a lot more mass than can be accounted for in stars, planets, gas clouds, and all the other stuff we can see. But they have no idea what it is.

Some astronomers have suggested that so-called primordial black holes (PBH) may be responsible for dark matter. Black holes are the extreme members of the cosmic zoo. Their gravity is so strong that nothing, not even light, the fastest thing in the universe, can escape. Normal black holes form when giant stars explode as a supernova, and the remaining core becomes so compressed by gravity that it collapses into a black hole. These are typically 5 to 10 times the mass of our sun. Black holes also do not emit or reflect any light.

PBHs form quite differently. When the universe began in the Big Bang, the density of matter was unimaginably high. Particles would constantly collide, sometimes sticking together. Usually, they would break apart in another collision a tiny fraction of a second later. Some areas of this infant universe were so dense that matter could clump together so tightly that they could form black holes millions of times smaller than a single proton. They may contain no more mass than a moon, a mountain, or even an elephant. Once formed, the extreme gravity holds them together regardless of how many collisions they may experience.

PBHs may well exist in such numbers that they could fill space. They might well be responsible for most or even all the dark matter that we know exists out there. Sarah Geller, a theoretical physicist at the University of California at Santa Cruz, co-authored a study of PBHs. They wondered how often one might pass through our solar system. "If there are lots of black holes out there, some of them must surely pass through our backyard every now and then," Geller said.

A primordial black hole interacting with Earth. Credit ESO/M Kornmesser

The researchers wondered "what might happen if a black hole punched through Earth's crust, or passed through our atmosphere, or left a crater on the moon," Geller said. "We even asked ourselves what would happen if one of these tiny black holes hit a human." After crunching the numbers, they realized that the chances of one hitting something as small as a person, or even our planet, were extremely tiny.

"We started thinking about the very precisely measured orbits of objects in the solar system," Geller said. "They could produce wobbles in the orbits of objects in the solar system that are big enough for us to measure." They estimate that one could pass through the inner parts of the solar system once every decade or so. The researchers aren’t claiming that PBHs exist, that they make up any of the dark matter, or that they are in or have passed through the solar system. But if they do exist in sufficient numbers that some or many have visited our planets, we can detect their gravitational pull.

Just to ease your mind, a separate study found that even if a PBH passed through your body, they are so tiny and so fast, they would likely cause no noticeable effect on your body.

Each month, I write an astronomy-related column piece for the Oklahoman newspaper. After it is published there, I post that same column to my blog page.

This is reprinted with permission from the Oklahoman and www.Oklahoman.com.

It's Time to Protect Extraterrestrial Locations that Might Support Life

 In 1972, Christopher Stone, a legal scholar at the University of Southern California, wrote a paper titled “Should Trees Have Legal Standing?” Although it took a few decades for the idea to catch on, it marked the beginning of the Rights of Nature movement. The United Nations has recently referred to it as the fastest-growing legal movement of the 21st Century.

Previously, a person or a group had to prove harm from some other person or company disturbing the environment before any legal action was taken. The Rights of Nature charter allows a person or a group to directly represent some aspect of nature that has rights of its own. It is similar to the legal cases in which parties, like children, can’t represent themselves, yet need legal protection. Some countries have put such protections in local and national laws, and some even in their constitutions.

Now, three scientists from the United Kingdom, an astrobiologist, an earth scientist, and a legal scholar, published a space policy paper saying such protections should extend to any extraterrestrial life we may discover and the environments in which they exist or may have existed.

We currently have probes on the surface of Mars seeking conditions, past or present, which might support life, as well as any living things that might currently exist there. Some moons, notably Europa, which orbits Jupiter, and Enceladus, a moon of Saturn, have organic materials that may well indicate the presence of living microbes there. Even a few asteroids exhibit some of the conditions that might be explained by extinct microbial life forms.

Enceladus, a moon of Saturn, is venting water and organic molecules.

Europa, a moon of Jupiter, possesses a 100-mile-deep ocean with organic molecules.

On our planet, despite this movement, we too often destroy natural environments, leading to a loss of habitat for species living there. This is one of the major causes of the extinction of flora and fauna on Earth. These scientists are advocating that we not do the same to extraterrestrial locations where life, however simple, might, or may in the future, exist.

In their Space Policy paper, the three chronicle many of the successes of the Rights of Nature movement. They say we need to extend this “circle of Rights beyond Earth” and suggest that environmental groups join forces with organizations that govern space activities, such as the United Nations Office for Outer Space Affairs.

We don’t always have a great track record of protecting species on Earth. This paper urges that we do not create the same sorts of environmental destruction in extraterrestrial locations that currently support or once may have supported any form of life.

 

Each month, I write an astronomy-related column piece for the Oklahoman newspaper. After it is published there, I post that same column to my blog page.

This is reprinted with permission from the Oklahoman and www.Oklahoman.com.

What Do We Do When We Discover Extraterrestrial Aliens?

 We humans have numerous scientific activities currently involved in the search for extraterrestrial intelligence (SETI). These include observations of numerous star systems looking for radio signals. as, for example, radar signals like those our airports send into space. The spacecraft we have sent to study the other planets and moons in our solar system have found intriguing hints of microbial life. However, we have yet to find any concrete proof of any life anywhere other than on Earth.

The James Webb Space Telescope can study planets orbiting other stars, searching for potential signs in their atmospheres that might indicate technological presence. Again, we have not yet found any such signs, only possible hints.

NASA's James Webb Space Telescope. Credit NASA

Most astronomers and other scientists believe it to be just a matter of time before such discoveries are made. What should we do then? Kate Genevieve from the Astro Ecologies Institution led a study that included 13 other researchers from various universities. They believe that previous preparation efforts, including the most recent guidelines, which were developed in 1989 (pre-World Wide Web), are outdated.

The study authors believe we need a detailed plan. NASA and the global scientific community, they say, should prepare for the moment humanity detects signs of extraterrestrial intelligence in the internet age. The research paper states that "a technosignature detection will trigger a complex global process shaped by uncertainty, misinformation, and multiple ideological stakeholders."

Getty Images

One area of preparation that the study says needs much more research on is how to understand minds that think radically differently from the way humans do. We need to develop "Other Minds" paradigms. Techniques the paper claims we need include studying whale songs and bird navigation to understand communication patterns in non-human entities. Whales, dolphins, and birds represent some of the most intelligent non-primate species on Earth, making studying them a good way to start learning how other intelligences think.

The authors also state that we need research studies on “the psychological, social, and global dynamics of post-detection scenarios.” They suggest analyzing science fiction to learn how different cultures imagine alien contact, giving us insight into how Earthlings as a whole might react, and providing an understanding of expectations and fears.

The team members strongly emphasize the need for strong international coordination of efforts and programs now. A fractured response by different nations could well lead to severe problems.

The paper doesn’t say that detection of extraterrestrial intelligence will occur soon, but it emphasizes that with new technologies like the Webb Space Telescope and the soon-to-be-operational Vera C. Rubin Observatory, such discoveries could come soon. The researchers feel we need to do much more before aliens come calling.

 

    Each month, I write an astronomy-related column for the Oklahoman newspaper. After it is published there, I post that same column to my blog page.

     This is reprinted with permission from the Oklahoman and www.Oklahoman.com.

Can Aliens Receive Our Radar Transmissions?

  

One of the most fundamental questions that we as a civilization might ask concerns the possibility that other intelligent beings may also inhabit our galaxy. On November 16, 1974, a group of scientists led by Frank Drake and Carl Sagan sent a message towards a large star cluster in the constellation of Hercules. At a distance of 13,000 light years, the message is still a long way from getting there. That event is considered the beginning of our search for other civilizations.

 

Frank Drake, credit SETI Institute.                     Carl Sagan, credit NASA Science

SETI stands for Search for Extra-Terrestrial Intelligence. The two most active organizations doing this are the SETI Institute and the Breakthrough Listen program. Both primarily use sophisticated radio telescopes to search for artificial radio signals from other planets that could support life. The thinking behind these projects is that any other intelligent civilization is likely to use radio signals for communication and detection.

The Allen Telescope Array, used by the SETI Institute.

The Very Large Array radio telescopes used by Breakthrough Listen. 

We humans use radio for these very purposes. Civil and military airport radar represents our most powerful radio signals. We’ve been using this technology since World War 2, and today’s radars are far more powerful and sophisticated. They are so powerful that they can be detected by any civilization with radio telescope technology at the same level as our SETI searches use.

Ramiro Saide, a Ph.D. student at the University of Manchester, led a research project to calculate how far away our radar facilities could be detected by civilizations at least as advanced as us. Our radio telescopes are capable of detecting a signal like what we emit from our airport radars from 200 light years away. There are more than 120,000 stars within 200 light-years of Earth. Although we currently have no evidence that any of those stars are home to intelligent aliens, we do know that they likely have some 200,000 or more planets that orbit them. Most of those aren’t capable of supporting life as we know it, but some may well be able to.

Saide said of the study that our radar signals would appear “clearly artificial to anyone watching from interstellar distances with powerful radio telescopes. These military signals can appear up to a hundred times stronger from certain points in space, depending on the observer’s location. Our findings suggest that radar signals – produced unintentionally by any planet with advanced technology and complex aviation system – could act as a universal sign of intelligent life.”

While our efforts to detect other civilizations have not yet provided any absolute proof of their existence, at least we know that our equipment could detect their radar emissions. The SETI Institute and Breakthrough Listen will continue to monitor the skies for any neighbors we might have.

 

Each month, I write an astronomy-related column piece for the Oklahoman newspaper. After it is published there, I post that same column to my blog page.

This is reprinted with permission from the Oklahoman and www.Oklahoman.com.

Making Distances in Space a Bit Easier to Imagine

 Warning to my readers: I’ll be using some big numbers in this article. Hopefully, I have made it as painless as possible.

Distances to objects in space from Earth are, well, astronomical. The Moon is 239,000 miles away. We’d have to travel 93,000,000 miles to reach the sun. That may seem like a great distance, but the next closest star, Proxima Centauri, is 22,876,214,400,000 miles away. Proxima Centauri is the closest of a three-star system known as Alpha Centauri. Using miles as a distance measure in space is quite impractical. The numbers get very big very quickly. Instead, we use light-years, the distance light travels in one year.

Artist's rendering of the Alpha Centauri three-star system. Credit NASA's Goddard Space Flight Center Conceptual Image Lab

Light travels at the fastest possible speed, moving through space at 186,000 miles per second. That’s 669,600,000 miles/hour or 5,865,696,000,000 miles/year. We call that distance, 5,865,696,000,000 miles, one light-year. Proxima Centauri is 4.25 light-years away, which is easier to write.

Let’s think about those astronomical distances in terms we can more easily visualize. Imagine one light year equals one mile. We all have a good understanding of how long a mile is. On this scale, light travels 0.002 inches per second. That’s a big change from the actual speed of light. The moon is 1.3 light seconds from Earth, or 0.0026 inches with this new light-year. We would orbit the sun, 8.3 light minutes away, from a distance of just under an inch. Proxima Centauri is 4.25 light years away, which now equates to 4.25 miles. Now it’s a lot easier to imagine these distances.

The fastest speed that any of our spacecraft has ever flown is the Parker Solar Probe. It used multiple gravity assists from Venus to get it close to the sun. It orbits so close to the sun that it passes through the sun’s outer atmosphere. In order to orbit the sun that closely, it has to move fast, achieving a maximum speed of 430,000 miles per hour. That’s really moving. But scaled to our new light speed of one mile per year, that corresponds to a mere 0.00064 miles per hour. At that speed, it would take 1,557 years to reach Proxima Centauri. Even in this shrunken universe, our Milky Way galaxy is 100,000 miles across, and our closest comparably large galactic neighbor, the Andromeda Galaxy, is still a mind-numbing 2,537,000 miles away.

As you can see, our universe is so incredibly large, even when shrunk by a factor of 5,865,696,000,000, it’s still huge beyond easy comprehension.

 

Each month, I write an astronomy-related column piece for the Oklahoman newspaper. After it is published there, I post that same column to my blog page.

This is reprinted with permission from the Oklahoman and www.Oklahoman.com.

Do "Dark Comets" Pose a Danger to Earth?

 You have probably seen pictures of comets with their long tails of dust and ice sweeping majestically behind them. That tail is one of the defining characteristics of comets. Small objects orbiting the sun that do not sprout a tail have long been considered to be asteroids. While astronomers have found some “dead” comets, those with no tail being pushed off by the sun, they have become asteroids.

As the ice melts from the comet by the sun’s heat, it pushes off the comet with a small force. Think of a pot of water evaporating. Even though you can’t feel the “wind” caused by this water vapor leaving the water, it’s there, and it pushes back on the water with a tiny but persistent force. With comets, this force of the vaporized ice leaving the comet acts like a tiny rocket motor. It can push the comet in its orbit in a way that astronomers can measure. The orbit of a comet isn’t controlled solely by the gravity of the sun, planets, and other objects in our solar system, but also due to this outgassing. Asteroids don’t behave this way.

Or so astronomers thought.

In 2016, astronomer David Farnocchia, with NASA’s Center for Near-Earth Object Studies, discovered something quite puzzling. He found an asteroid, 2003 RM, whose motion through the solar system couldn’t be fully accounted for by the gravity of other bodies. It behaved like a comet shooting water vapor into space, except that he could find no evidence of that.

There is another force, known as the Yarkovsky effect, which can alter the orbit of small bodies around the sun. As photons from the sun impact a space rock, they deliver an almost imperceptible push on the rock. Though minuscule, it can, over time, affect the rock’s orbital path. Also, the sunward side heats up from the sun’s thermal energy. But, as the asteroid rotates, the heated side rolls into the dark and radiates the excess heat into space, again providing a tiny bit of thrust. Farnocchia took all of that into account for 2003 RM, yet it still couldn’t explain the small deviation of the asteroid’s orbit.

Comet Tsuchinshan-ATLAS credit Wladimir Bulgar - Science Photo Library via Getty Images

With all comets, as the ice is vaporized and outgassed from the sun’s heat, it also releases dust trapped in the ice. That beautiful tail we see coming from a comet is actually composed of dust. But even using our biggest and best telescopes, no one has found any dust trailing 2003RM. It behaved as if it had a tiny rocket engine attached to it. Eventually, Farnocchia and other astronomers found thirteen more such objects. They dubbed them “dark comets.”

This is more than just a curiosity for astronomers. Farnocchia’s job is to search for asteroids that have a possibility of hitting Earth. “My job,” he says, “is to predict how things move in space. So if there’s something novel or unexpected, that’s where the advance in the field lies for us.”

Current telescopes can easily see any dust that might be coming off of a comet, but none has been found to date. New telescopes planned or already under construction will be able to detect any tiny bits of water vapor that may be puffing off these dark comets. And since some are close enough that they might have a chance of collision with Earth down the road, being able to predict their position and movement may become more crucial in the future. For now, he will monitor them and track their movements, just in case one wanders too close to us.  

Do Cosmic Events Cause Mass Extinctions on Earth?

 Scientists recognize five major mass extinctions in Earth’s history, episodes when a large fraction of life all over our planet went extinct in a very short time on geological time scales. Scientists blame various causes for these extinctions. Climate change was often the real killer, but the cause of climate change varied.

The most recent mass extinction, the K-T extinction 66 million years ago, is perhaps the most famous and best understood of the major extinctions. It led to the end of the dinosaurs and most marine reptiles. At that time, an asteroid 6 miles in diameter slammed into Earth just off the coast of what is now the Yucatan Peninsula in Mexico. It threw hot ash and molten rock into the air that covered the planet, resulting in worldwide fires, killing off many species. The resulting cloud of debris and smoke then reduced sunlight from reaching the planet’s surface for a period of years, causing the death of many plant species which dramatically diminished the entire food chain.

A new study suggests an astronomical cause for two other extinction episodes. The Ordovician extinction event occurred 443.8 million years ago. This was a time known for rapid diversification in marine life and the appearance of the first plants on land. Scientists estimate that 71% of species disappeared during this event.

The Late Devonian mass extinction occurred 372 million years ago leading to the extinction of nearly 70% of species. It is the least understood of the five major events, and scientists have offered several possible explanations for it. The new study provides plausible astronomical explanations for both of these events.

In both the Ordovician and late Devonian extinction events, there is evidence that Earth’s ozone layer was severely depleted. A new study led by Dr. Alexis Quintana at the University of Alicante in Spain, including other researchers from Keele University in England, puts the blame for both events on nearby supernovas.

When a massive star runs out of fuel, it explodes with so much energy that a single supernova can temporarily release more energy than its entire host galaxy. The debris includes not only high-energy radiation, like X-rays and gamma rays, it also includes cosmic rays, charged particles moving at nearly the speed of light. A nearby supernova can blast enough energy to destroy our ozone layer. With that protective shield gone, the high-energy cosmic rays and the deadly radiation can bathe Earth’s surface at lethal levels.

The Crab Nebula, a supernova remnant in the constellation of Taurus. 

Credit NASA, ESA, and the Hubble Space Telescope Institute.

Life on our planet owes its existence to supernovas, as all elements heavier than hydrogen and helium – including oxygen, carbon, calcium, iron, and all the chemical elements that make us up – are created in those stellar explosions. As the authors say in the study, it is "a great illustration for how massive stars can act as both creators and destructors of life".

Dr. Quintana states, "Supernova explosions bring heavy chemical elements into the interstellar medium, which are then used to form new stars and planets. But if a planet, including the Earth, is located too close to this kind of event, this can have devastating effects."

It seems the universe can give us life, but can also take it away.

 

Each month, I write an astronomy-related column piece for the Oklahoman newspaper. After it is published there, I post that same column to my blog page.

This is reprinted with permission from the Oklahoman and www.Oklahoman.com.

Are We Close to Finding Extraterrestrial Life?

 The topic of many of my articles involves the search for extraterrestrial life. I look at what conditions are needed to support life on Earth and see if such environments exist elsewhere. For example, we found seasonal variations of methane in the Martian atmosphere. On our planet, methane is almost exclusively associated with life. I’ve written about astronomers’ efforts to find and study planets orbiting other stars to determine if they orbit in the habitable zone where water can exist on the surface. On Earth, virtually wherever we find water, we find living creatures. That may only be microbial life, such as that found in acidic hot springs or water trapped far below the surface, but life nonetheless.

Even if we only find such microbial life, that would be an astounding discovery. It would tell us that life can develop in locations other than Earth which at the moment is the only location in the universe where life is known to exist.

Recently, a newsletter called The Conversation ran an article in which the authors polled astrobiologists and other scientists on their belief in extraterrestrial life. The Conversation is an online source of articles written by researchers and academics across all disciplines. It gives them a platform to present their work to the public. We often read articles that say finding extraterrestrial life is “only a matter of time”, or “we are close to finding alien life.” And yet, we still await that discovery.

Exoplanets in their star's habitable zone. Are we close to discovering exo-life?

In 2024, three researchers – Peter Vickers, a Professor in Philosophy of Science at Durham University, Henry Taylor an Associate Professor in the Department of Philosophy at the University of Birmingham, and Sean McMahon, of the University of Edinburgh – did surveys, polling a number of astrobiologists, those scientists who study and look for the chances of life elsewhere, and scientists in other fields on their beliefs of the existence of alien life. They asked about their beliefs, based on all the research to date, of the existence of basic lifeforms, i.e. microbial life, complex forms, i.e. multicellular life, and intelligent extraterrestrial life.

Altogether, they received responses from 521 astrobiologists and 534 non-astrobiologists. Of the astrobiologists, 86.6% said they “agree” or “strongly agree” that extraterrestrial life, at least at the basic level, exists elsewhere. Less than 2% disagreed with the sentiment and 12% claimed to be neutral on the possibility. Of the non-astrobiologists, 88.4% also marked “agree” or “strongly agree” with the question. Scientists who don’t study the possibility of extraterrestrial life are not more skeptical than those who do. The authors of the survey felt that to be a rather significant result.

The survey asked about each level of life – basic, complex, and intelligent – separately. The results when asked specifically about whether “intelligent” aliens exist were not quite as optimistic. Only 67.4% of astrobiologists and 58.2% of other scientists agreed, still more than half. Only 10.2% of astrobiologists disagreed with that statement.

This survey cannot in any way offer proof of life elsewhere, but the preponderance of scientific research and evidence leads most scientists, at least in these fields, to accept the likelihood. Astronomers estimate that in our galaxy alone a trillion extrasolar planets, those orbiting other stars, exist. They further estimate that billions of Earth-like planets orbit in the habitable zone of their parent star.

Life on Earth is proving to be far more robust than we previously thought. Microbes called extremophiles can survive in all kinds of environments once thought unable to support any kind of life. Creatures called tardigrades, or water bears, have even been shown to survive in airless, radiation-filled outer space beyond our planet. I suspect that the existence of such extremophiles that survive in these hazardous or toxic locations is a large part of the thought processes of these scientists.

Perhaps it really is only a “matter of time” before we discover alien life forms. And. Some scientists say we may not even recognize alien creatures as living at first. We have no idea if “life as we know it” is all that there can be.

 

Each month, I write an astronomy-related column piece for the Oklahoman newspaper. After it is published there, I post that same column to my blog page.

This is reprinted with permission from the Oklahoman and www.Oklahoman.com.

Did Planets from the Inner Disk of the Milky Way Become Rogue Planets?

 We think of a planet as a non-luminous body that orbits a star, like the planets of our solar system. But that’s not always the case.

All stars form from clouds of gas and dust that collapse inward due to the pull of gravity. The pressure caused by the gravitational crunch squeezes gas in the center of each cloud so tightly that it heated the gas to extreme temperatures, generating thermonuclear reactions, and a new star is born. Our sun flared into existence four and a half billion years ago, far younger than the oldest stars, which are born in other parts of the galaxy.

But there was still quite a bit of leftover gas and dust surrounding the young sun which formed a disk around the new star. This leftover bit eventually becomes all of the planets, moons, comets, and asteroids that orbit our sun.

Our solar system lives in the spiral arms of the Milky Way galaxy. Most of the galaxy’s younger stars like our sun are in the spiral arms. Astronomers estimate that virtually all of these stars have planets, an average of two and a half planets per star.

The older stars of our galaxy mostly reside in a bulge surrounding the center of the Milky Way. Stars there have on average barely one planet per star.  MIT astrophysicist Tim Hallatt thinks he knows why. “The puzzle is, these planets (in the spiral arms) are very common,” Hallatt says. “And yet when we look at this other dominant population of stars in the Milky Way, they’re less common. So what’s going on?”

As is the case with all large galaxies like ours, when the Milky Way first formed some 12 billion years ago, star formation was fast and furious, a time Hallatt describes as galactic chaos, what astronomers generally refer to as “cosmic noon.” Also, the stars there were more closely bunched together than the stars in our neighborhood. The greater levels of energetic radiation from the process of rapid star formation plus the relative proximity of stars meant that the stars during cosmic noon experienced ten million times greater levels of radiation. This intense radiation would have heated the gas surrounding all these rapidly forming stars. The greater levels of radiation and heat blew away much of the remaining gas, leaving less raw material for planets.

When astronomers search for planets beyond our own solar system, they look at other stars. We currently know of more than 5000 such exoplanets, and the more we look, the more we find. Astronomers also find lots of rogue planets, planets that don’t orbit any star. They may have formed around a star but were ejected from their home stellar system, perhaps due to close passage of another star. The gravity of the passing star can rip a planet away from its home. Astronomers estimate that perhaps as many as four trillion rogue planets exist in our galaxy alone. That’s a huge number.

Artist's conception of a Rogue Planet

It’s likely that some of those rogue planets formed on their own, not as part of a stellar system. Perhaps some of the gas and dust blown out by the stars formed during the crowded cosmic noon eventually coalesced into rogue planets. Many of these rogue planets could have orbited a star but for the early period of rapid star growth.

Rogue planets may easily outnumber the stars in our galaxy. And some of those rogue stars may be causalities of the cosmic noon timeframe of our Milky Way galaxy.

Each month, I write an astronomy-related column for the Oklahoman newspaper. After it is published there, I post that same column to my blog page.

This is reprinted with permission from the Oklahoman and Oklahoman.com.

Should We Call Pluto a Planet?

Astronomers once called Pluto the ninth planet. In 2006, the International Astronomical Union, IAU, downgraded Pluto to the status of dwarf planet. After the New Horizons craft flew by Pluto in 2015, it showed us a very dynamic world. Many astronomers and a large percentage of the public now believe we should reconsider Pluto’s demotion.

Pluto as seen by the New Horizons spacecraft. 

Since before written history, humans have known of seven regularly observed heavenly bodies that didn’t behave like the vast majority of stars. They called them planets, Greek for “wanderer.” In those ancient times, they considered anything that changed its position relative to the “fixed stars” to be a planet. Since both the sun and the Moon moved relative to the fixed stars, they were also considered planets until Copernicus proved that planets circled the sun and the Moon circled Earth.

Astronomers then recognized six planets, Mercury, Venus, Earth, Mars, Jupiter, and Saturn. Comets also orbited the sun, but because they had weird orbits and grew a tail, they were considered different types of celestial objects. That changed in 1781 when William Herschel discovered Uranus and Italian astronomer Giuseppe Piazzi discovered Ceres in 1801 between Mars and Jupiter while searching for comets. Both orbited the sun.

Ceres, the largest member of the Asteroid Belt.

Initially, astronomers called Ceres the smallest planet until many more such objects were discovered in the same area of our solar system. They reclassified Ceres and all those other even smaller objects as “asteroids,” calling that region the Asteroid Belt.

In 1846, two astronomers independently discovered Neptune, adding an 8^th planet to the solar system. Clyde Tombaugh added Pluto in 1930, making nine planets, and there it stayed for years.

In the 1990s, astronomers began finding many more objects beyond Neptune. They were small like Pluto and in the area of our solar system that was relatively crowded, unlike the inner parts. Some astronomers feared that it might be time to get a more scientifically based definition of “planet.”  

At the 2006 IAU meeting, astronomers agreed to redefine what constitutes a planet. There were two camps: geophysicists and dynamists. They all agreed that it had to orbit a star. Geophysicists said that any object big enough that its gravity pulled it into a spherical or nearly spherical shape should be a planet. Dynamists argued that a planet must also be large enough to “clear its orbital area of debris.” Ceres couldn’t be a planet since, even though it is round, there were many asteroids in the same region. Likewise, round Pluto shared its region with many thousands of objects.

The dynamists won. Pluto, Ceres, and other round solar system bodies became dwarf planets. Along with those two, astronomers now recognize three others, Haumea, Makemake, and Eris, all beyond Neptune, as dwarf planets. There may be many more that we just don’t have enough data on yet.

Count me in the camp of the geophysicists. If it’s big enough to pull itself into a nearly circular shape, technically called hydrostatic equilibrium, then I believe it should be a planet. I’m convinced that the dynamists just didn’t want to remember that many planet names.

  

    Each month, I write an astronomy-related column piece for the Oklahoman newspaper. After publishing it there, I post that same column to my blog page.

   This is reprinted with permission from the Oklahoman and www.Oklahoman.com.