Odd Names of Solar System Bodies

Odd Names of Solar System Bodies

We are pretty used to the names of the major objects in our Solar System. Most names are taken from Greek mythology, such as Jupiter, Saturn, Venus, Mercury, Mars, Uranus, Pluto, vnd Neptune. There are many more objects named however, and some of them quite odd.

  1. Ganymede, a moon of Jupiter. The name is from the Greek Ganymēdēs, Latin Ganymedes, or Catamitus, in Greek legend, was the son of Tros (or Laomedon), king of Troy. Because of his unusual beauty, he was carried off either by the gods or by Zeus, disguised as an eagle, or, according to a Cretan account, by Minos, to serve as cupbearer. In compensation, Zeus gave Ganymede’s father a stud of immortal horses (or a golden vine). The earliest forms of the myth have no erotic content, but by the 5th century
    BCE it was believed that Ganymede’s kidnapper had a homosexual passion for him; Ganymede’s kidnapping was a popular topic on 5th-century Attic vases. The English word catamite was derived from the popular Latin form of his name. He was later identified with the constellation Aquarius.
  2. Mister Spock Asteroid. Not what you were thinking here. This has nothing to do with the Star Wars character. In fact, this was named after the pet of discoverer James B. Gibson. The recent sad loss of photographer, director and actor Leonard Nimoy is most keenly felt by the millions of fans who loved the sci-fi character he shall always be most closely associated with—Star Trek‘s coolly logical and pointy-eared Vulcan science officer, Mr. Spock. As befits someone who toured the fictional Galaxy furthering scientific knowledge, astronomers have a tangible reminder of the starship Enterprise‘s first officer in the form of an asteroid that will always bear his name. James B. Gibson discovered 2309 Mr. Spock (1971 QX1) from Yale-Columbia Station at El Leoncito, Argentina on 16th August 1971. It soon became apparent that this was a main-belt asteroid between the orbits of Mars and Jupiter, orbiting 3 astronomical units from the Sun every 5.23 years. Subsequent analysis revealed that 2309 Mr. Spock is a 13-mile (21-kilometre)-wide body rotating on its axis every 6.7 hours. zktin-belt asteroid 2309 Mr. Spock (1971 QX1) is a 13-mile-wide body rotating on its axis every 6.7 hours that orbits 3 astronomical units from the Sun every 5.23 years. Currently 17th magnitude in the constellation of Taurus, it’s still a viable astrophotographic target for 10-inch telescopes and larger. This is a two-minute ISO1600 exposure at f/2 with a C11 and DSLR on 10th March at 21:15 UT. Image credit: Ade Ashford. Live long and pros-purr.
  3. James Bond. This is a numbered minor planet, discovered October 5, 1983. It is classified as an inner planet
  4. Tom Hanks. Asteroid 12818 Tomhanks swung within about 151 million miles of Earth on Sept. 12, while 8353 Megryan came about 191 million miles away on Sept. 27. Neither came closer than the distance between the Earth and the sun, and they did not pose any risk to our planet. A lot of scientists have named asteroids after their favorite celebrities, and considering Tom Hanks is somewhat of a favorite (read, Apollo 13) among astronauts, he makes the cut. However, Tom isn’t the only star to have an asteroid named after him. There’s Meg Ryan, Chaplin, and Van Damme among others.
  5. Monty Python. The hilarious British comedy troupe are so famous among the astronauts that each member of the crew also have an asteroid named after them.
  6. Makemake sounds like the most delicious Japanese snack ever. Would make for the perfect dwarf planet wouldn’t it?
  7. Beowulf Asteroid. Asteroid 38086, Beowolf, was discovered on May 5, 1999 by the Lowell Observatory Near-Earth Object Search (LONEOS) at the Anderson Mesa Station of Lowell Observatory near Flagstaff, Arizona. It has a period of 1 years, 253 days. It was named for the great Scandinavian warrior Beowulf, hero of the early medieval British epic poem.
  8. (7470) Jabberwock is a main-asteroid of the main belt, discovered on May 2, 1991 by the Japanese astronomer Takeshi Urata at the Nihondaira Observatory.The asteroid is part of the Vesta family, a large group of asteroids. (7470) Jabberwock was named after the mystical creature Jabberwock, the main theme of the classic nonsense poem Jabberwocky from the story Through the Looking Glass, by Lewis Carroll.
  9. Petit-Princebelt. This prince is so petite that it’s not even an asteroid. 45 Eugenia has a moon called Petit-Prince, named after Antoine de Saint-Exupéry’s The Little Prince. The children’s book follows the exploits of a boy who lived on an asteroid and explored other asteroids, as well as Earth.
  10. Adam Curry. Discovered Marcy 20, 1998 and named for the infamous Adam Curry
  11. This minor planet was named after Amol Aggarwal, who won the Intel Science Talent search in California in 2011, and got the planet as a prize. This isn’t the only Indian named, however. There’s Bhasin, B\att, Bhattacharya, and Yogeshwar. All these planets have been named by the scientists who discovered them.
  12. Anandapadmanabum. A Solar System small body, 30269 Anandapadmanaban (2000 HS50)

The list goes on to include: Ask, Bam, Babcock, Bacon, Beer, Brest, Hippo, Lust

All these minor objects do exist in real, and aren’t a figment of my imagination. The source is http://minorplanetcenter.net/.

Forming a Black Hole

Forming a Black Hole[1]

On July 2, 1967, a network of satellites designed to detect tests of nuclear weapons recorded a flash of gamma rays coming from the wrong direction—outer space.

And so it was that human astronomers were tipped to the existence of one of the most violent phenomena of nature. Today, they know that about once a day somewhere in the observable universe, an explosion called a gamma-ray burst occurs, releasing more energy in a few seconds than our galaxy does in a year.

These magnificent cosmic conflagrations are as far away as they are rare, which is just as well. If one happened nearby, in our own galaxy, we could be swathed with radiation. The closest gamma-ray burst whose distance has been measured happened some 119 million light-years from us, far outside the so-called Local Group, which contains our own Milky Way galaxy. The farthest so far recorded is now 31 billion light-years away, as calculated by the mathematics of the expanding universe; it happened when the universe was only 500 million years old.

Gamma-ray bursts are thought to be the final step in the series of transformations by which stars shrink and slump from blazing glory to oblivion, winding up as bottomless deadly dimples in the fabric of space-time—that is to say, as black holes.

The hierarchy of dead stars goes like this: Stars like the Sun, when they run out of thermonuclear fuel, shrink to cinders known as white dwarfs, the size of Earth. Stars more massive than the Sun might collapse more drastically and undergo a supernova explosion, blasting newly formed heavy elements into space to enrich future stars, planets and perhaps life, and leaving behind crushed cores known as neutron stars. These weigh slightly more than the sun but are only 12 miles or so in diameter—so dense that a teaspoonful on Earth would weigh as much as Mount Everest.

Such an explosion, bright enough to be seen in daylight, happened in 1054, Earth time, as told by Chinese astronomers and the ancient inhabitants of Chaco Canyon in what is now New Mexico. That supernova left behind the Crab nebula, a tangle of glowing shreds of gas and a pulsar—a magnetized neutron star spinning 30 times a second, whipping the gas with magnetic fields that make it glow.

Neutron stars, theorists say, are the densest stable form of matter, but they are not the end of the story. According to theory, too much mass accumulating on a neutron star can cause its collapse into a black hole, an abyss from which not even light can escape. The signature of such a cataclysm would be a gamma-ray burst, astronomers say.

Supercomputer simulations by astronomers led by Luciano Rezzolla of the Institute of Theoretical Physics in Frankfurt have recently showed this would work.

The simulation, as it unwound over six weeks of supercomputer time at the Max Planck Institute for Gravitational Physics, started with two neutron stars orbiting each other at a distance of 11 miles. That would not be unusual in the universe; most stars are in fact part of double-star systems and several pairs of pulsars orbiting each other are already known. They will eventually collide because such dense, heavy objects lose energy rapidly and spiral together.

In the case of Dr. Rezzolla’s computation, it took seven milliseconds for tidal forces from the larger star’s gravity to rip apart the smaller star and unwind it into a spiral resembling flaming toothpaste writhing with magnetic fields and begin munching up the gas.

The excess plasma forms a fat disk around the new black hole, and its magnetic fields, a billion times stronger than those in the Sun, align to channel beams of radiation and particles out at the speed of light. The result is a gamma-ray burst visible across the universe, carrying the news of doom—the last astronomers will ever hear of these stars.

For those two stars, the last bang was the best. Oblivion can be such a lovely sight.

[1] Dennis Overbye, “How to Make a Black Hole,” New York Times (October 8, 2014). The graphic is from Astronews in Astronomy (45, 7, July 2017), p 15

Copernicus at 493

Copernicus at 493[1]

The whole world should observe along with the Poles, the birthday of Copernicus, and should continue to celebrate the 19th of February in his memory so long as the Earth swings in its orbit.; for what this boy, born 450 years ago yesterday [article written February 20, 1923; Copernicus born, February 19, 1473 and in 2017 he would be 493], and christened Nichola Koppernick, son of a native of Cracow, conceived as the order of the universe is “the capital event of modern thought.” By it mankind’s outlook on the universe has been fundamentally changed. The young Koppernick was a student in the University of Cracow the year in which Columbus discovered America, giving himself to mathematical science and painting. He afterward studied law and attended mathematical lectures in Bologna and still later studied music in Padua and took his degree in canon law in Ferrara. He then devoted his medical skill to the service of the poor, his economic knowledge to the reform of the currency in the Prussian provinces of Poland, and his astronomical genius to the development of a new cosmic theory which has come to bear his name.

It was while he was in the midst of such studies and ministries that the name “America” was first given by others to the fringe of this continent and graven on a map published at St. Dié, at the foot of the Vosges Mountains, in Southeastern France. Our continent was thus christened under the Ptolemaic geocentric system. But our national life made its beginnings under the Copernican system and had from the first a “shuddering sense” of physical immensity. It is inconceivable that this new physical conception has not mightily affected man’s social and religious conceptions, and especially those of Americans. With the enlargement of the universe under it, and the accompanying diminution of the relative size of Earth—made still smaller by man’s improved means of communication—we no longer picture our planet as a flat area divided into exclusive, provincial or national strips spanned by a Ptolemaic sky. We find ourselves “in the same boat” on a sea of practically infinite space.

In observing the birthday of Copernicus, the Polish astronomers have fitly gathered in their first congress[2] and proudly remembered what their science has given to mankind; and the Polish people have with good reason held their celebrations all over Poland in honor of the son of the city of Thorn[3] (again in Polish territory in 1923, 5 years after the end of WWI) and the academic son of the University of Cracow (once more a Polish university). But it would be profitable for the whole world—scientists, statesmen, warriors, philosophers, teachers, pupils and the people in general—to pause and consider what was the real significance of the gift of Copernicus. The corollary of his theory is a world-wide solidarity of human interest. There is no escape from it. If an international holiday were to be added to the many holidays in the various calendars of the world, it should be one on which the birthday of Copernicus is solemnly observed—for he discovered the universe.

[1] Published in the New York Times (February 20, 1923, p. 16)

[2] First Polish Philosophical Congress held in Lvov, 1923.

[3] Thorn is the German name. In Polish, it is Toruń, a city in northern Poland, on the Vistula River. In the aftermath of World War I, the Polish people broke out in the Greater Poland Uprising on December 27, 1918, in Poznań after a patriotic speech by Ignacy Paderewski, a famous Polish pianist. The fighting continued until June 28, 1919, when the Treaty of Versailles was signed, which recreated the nation of Poland.

Earth May Have Been Shaped Like a Donut

Earth May Have Been Shaped Like A Donut At One Point In Time[1]

The new synestia theory proposes a new type of planetary object and another theory for how the Moon formed.

A to-scale illustration of the synestia process is shown above.

Astronomers have proposed a new type of planetary object they are calling synestia, where a celestial body violently collides with another body, resulting in a donut-shaped disk of vaporized rock. After some time, the body will cool down and turn into the solid, round planets we currently know.

Sarah Stewart, a planetary scientist at the University of California Davis, and Simon Lock, a graduate student at Harvard University in Cambridge, co-authored the study that was published in the Journal of Geophysical Research: Planets.

The name synestia combines the prefix “syn-” meaning “together” and Estia, the Greek goddess of architecture and structures.

The idea was modeled after ice skaters doing a spin—when they put their arms out to the side they slow down but when they tuck their arms in, their momentum stays constant, but their angular velocity increases and they spin faster.

The team was interested in how that idea would apply to rapidly spinning planets colliding with each other and how it would impact the angular momentum.

The people doing the study believe the collision that formed Earth likely caused a synestia before it cooled back down and formed into the solid, round object it is today. The researchers said those days probably didn’t last more than 100 years, though.

On top of a theory for planets how planets have formed, the study also lends to the idea of the formation of the Moon since its composition is similar to that of Earth’s.

[1] See Nicole Kiefert, Astronomy.com, “Earth May Have Been Shaped Like A Donut At One Point In Time,” (published May 30, 2017), downloaded May 30, 2017

Eddington Observes Solar Eclipse to Test General Relativity

May 29, 1919: Eddington Observes Solar Eclipse to Test General Relativity

One of Eddington’s photographs of the May 29, 1919, solar eclipse. The photo was presented in his 1920 paper announcing the successful test of general relativity.

When Albert Einstein published his general theory of relativity (GR) in 1915, he proposed three critical tests, insisting in a letter to The Times of London that if any one of these three proved to be wrong, the whole theory would collapse.

  • Advance of the perihelion of Mercury
  • Deflection of light by a gravitational field
  • Gravitational red shift

Once he had completed his theory, Einstein immediately calculated the advance of the perihelion of Mercury, and he could hardly contain himself when GR produced the correct result. The next classical test was the deflection of light by a gravitational field, first performed by Sir Arthur Eddington in 1919.

Born to Quaker parents in December 1882, Arthur was just two years old when he lost his father to a typhoid epidemic that ravaged England. As a child, Eddington was enamored of the night sky and often tried to count the number of stars he could see. Initially Eddington was schooled at home, but when he did start attending school, he excelled so much in mathematics that he won a scholarship to Owens College in Manchester at age 16. He graduated with first class honors in physics, and promptly won another scholarship to attend Trinity College at Cambridge University.

Eddington completed his M.A. in 1905. First, he worked on thermionic emission at the Cavendish Laboratory, and then tried his hand at mathematics research, but neither project went well. He briefly taught mathematics before re-discovering his first love: astronomy. Eventually he found a position at the Royal Observatory in Greenwich, specializing in the study of stellar structure. By 1914 he had moved up to become director of the Cambridge Observatory; a Royal Society fellowship and Royal Medal soon followed.

During Eddington’s tenure as secretary of the Royal Astronomical Society, Willem de Sitter sent him letters and papers about Einstein’s new general theory of relativity. Eddington became Einstein’s biggest evangelist at a time when there was still considerable wartime hostility and mistrust toward any work by German physicists. He soon became involved in attempts to confirm one of the theory’s key predictions.

Since the masses of celestial bodies would cause spacetime to curve, Einstein predicted that light should follow those curves and bend ever so slightly. Isaac Newton had also predicted that light would bend in a gravitational field, although only half as much. Which prediction was more accurate? Scientists feared that measuring such a tiny curvature was simply beyond their experimental capabilities at the time.

It was Britain’s Astronomer Royal, Sir Frank W. Dyson, who proposed an expedition to view the total solar eclipse on May 29, 1919, in order to resolve the issue. Eddington was happy to lead the expedition, but initially the venture was delayed. World War I was raging, and the factories were too busy meeting the country’s military needs to make the required astronomical instruments. When the war ended in November 1918, scientists had just five months to pull together everything for the expedition.

Eddington took nighttime baseline measurements of the positions of the stars in the Hyades cluster in January and February of 1919. During the eclipse the Sun would cross that cluster, and the starlight would be visible. Comparison of the baseline measurements of a star’s position and the corresponding measurements made during the eclipse, when that star was just visible at the limb of the sun, would determine whether Einstein or Newton was right.

Then Eddington set sail for Principe, a remote island off the west coast of Africa, sending a second ship to Sobral, Brazil—just in case the weather didn’t cooperate and clouds obscured the view. It proved to be a smart decision. Eddington’s team was dismayed when heavy rains and clouds appeared on the day of the eclipse, although the skies cleared sufficiently by the time of the event to allow them to make their measurements. The Brazilian team had their own challenges: The tropical heat warped the metal in their large telescopes, forcing them to also use a smaller 10-centimeter instrument as backup.

Once the two teams had analyzed their results, they found their measurements were within two standard deviations of Einstein’s predictions, compared to twice that for Newton’s, thus supporting Einstein’s new theory. News of Eddington’s observations spread quickly and caused a media sensation, elevating Einstein to overnight global celebrity. (When his assistant asked how he would have felt had the expedition failed, Einstein is said to have quipped, “Then I would feel sorry for the dear Lord. The theory is correct anyway.”)

Not everyone immediately accepted the results. Some astronomers accused Eddington of manipulating his data because he threw out values obtained from the Brazilian team’s warped telescopes, which gave results closer to the Newtonian value. Others questioned whether his images were of sufficient quality to make a definitive conclusion. Astronomers at Lick Observatory in California repeated the measurement during the 1922 eclipse, and got similar results, as did the teams who made measurements during the solar eclipses of 1953 and 1973. Each new result was better than the last. By the 1960s, most physicists accepted that Einstein’s prediction of how much light would be deflected was the correct one.

Eddington succumbed to cancer in November 1944 after a long illustrious career. In addition to his many scientific contributions, he once penned a lyrical parody of The Rubaiyat of Omar Khayyam about his famed 1919 expedition:

Oh leave the Wise our measures to collate
One thing at least is certain, LIGHT has WEIGHT,
One thing is certain, and the rest debate –
Light-rays, when near the Sun, DO NOT GO STRAIGHT.


NASA’s Jupiter Mission

NASA’s Jupiter Mission[1]

Multiple images combined show Jupiter’s south pole, as seen by NASA’s Juno spacecraft from an altitude of 32,000 miles. The oval features are cyclones. (Credit NASA/JPL-Caltech/SwRI/MSSS/Betsy Asher Hall/Gervasio Robles)

The top and bottom of Jupiter are pockmarked with a chaotic mélange of swirls that are immense storms hundreds of miles across. The planet’s interior core appears bigger than expected, and swirling electric currents are generating surprisingly strong magnetic fields. Auroral lights shining in Jupiter’s polar regions seem to operate in a reverse way to those on Earth. And a belt of ammonia may be rising around the planet’s equator.

Those are some early findings of scientists working on NASA’s Juno mission, an orbiter that arrived at Jupiter last July.

Juno takes 53 days to loop around Jupiter in a highly elliptical orbit, but most of the data gathering occurs in two-hour bursts when it accelerates to 129,000 miles an hour and dives to within about 2,600 miles of the cloud tops. The spacecraft’s instruments peer far beneath, giving glimpses of the inside of the planet, the solar system’s largest.

“We’re seeing a lot of our ideas were incorrect and maybe naïve,” Scott J. Bolton, the principal investigator of the Juno mission, said during a NASA news conference on Thursday, May 25, 2017).

Two papers, one describing the polar storms, the other examining the magnetic fields and auroras, appear in this week’s issue of the journal Science. A cornucopia of 44 additional papers are being published in the journal Geophysical Research Letters. The papers describe findings based largely on the first two close passes of Jupiter in which Juno was able to make measurements. Juno has now made five, with the next on July 11, 2017, when it is to pass directly over the Great Red Spot.

Scientists are puzzled to see that the familiar striped cloud patterns of Jupiter may be only skin deep. An instrument collecting microwave emissions probes the top layers of the atmosphere, but that data does not reflect what is seen in the clouds. “These zones and belts either don’t exist or this instrument isn’t sensitive to it for some reason,” Dr. Bolton said.

The microwave instrument did detect a band of ammonia rising in the equatorial region from at least a couple of hundred miles down—“the most startling feature that was brand-new and unexpected,” Dr. Bolton said.

In measuring the gravitational field, scientists hoped to learn what lies at the center of Jupiter. Some predicted a rocky core, perhaps the size of Earth or several Earths. Others expected no rocky core, but hydrogen, the planet’s main constituent, all the way down. “Most scientists were in one camp or the other,” Dr. Bolton said, “and what we found is neither is true.” Instead, the data suggests a “fuzzy core,” one that is larger than expected, but without a sharp boundary, perhaps partly dissolved.

The magnetic field is also not simple. “What scientists expected was that Jupiter was relatively boring and uniform inside,” Dr. Bolton said. “What we’re finding is anything but that is the truth.”

John E.P. Connerney, a scientist at NASA’s Goddard Space Flight Center in Greenbelt, Md., and the deputy principal investigator on the mission, reported spatial variations in the magnetic field that were much stronger than expected in some areas and much weaker in others.

The magnetic field is generated by the churning of electrically charged fluids at the core. On Earth, that comes from the convection of molten iron in the outer core. On Jupiter, the currents come from hydrogen, which turns into a metallic fluid under crushing pressures.

The spatial variations suggest that the dynamo of churning currents is larger than had been thought and may extend beyond the metallic hydrogen region, Dr. Connerney said.

For the magnetic field and gravity measurements, a glitch that has greatly slowed the pace of data gathering could turn out to be beneficial. A final engine burn last October was to put Juno in a 14-day orbit, but a pair of sluggish valves in the fuel system led mission managers to forgo that, and Juno remains in the 53-day orbit instead. The spacecraft is to make the same number of orbits and collect the same amount of data, and the longer mission means that Juno may be able to detect slow changes in the magnetic field.

More surprises were found at the top and bottom of Jupiter.

With Juno’s orbits passing almost directly over the north and south poles, scientists can better study the powerful auroras, which are generated by charged particles traveling along Jupiter’s magnetic field and colliding with molecules in the atmosphere. In Earth’s case, charged particles from the Sun speeding outward through the Solar System are diverted by the planet’s magnetic field toward the poles, generating light when they collide with air molecules. The expectation was that the same would occur at Jupiter, and it does to some extent.

But Juno also detected charged particles—mostly electrons—traveling in the opposite direction at Jupiter: out of the planet into space. “It’s a 180-degree turnabout from the way we were thinking about those emissions,” Dr. Connerney said.

He said a voltage differential in the atmosphere was drawing the electrons upward.

Earlier photographs of the polar regions were taken from a sharp angle, with details hard to make out. Juno revealed that the clouds there are very different from the usual Jupiter stripes. “What you see is incredibly complex features, the cyclones and anticyclones all over the poles,” Dr. Bolton said.

Planetary scientists had wondered whether Jupiter would have a giant hexagonal pattern like that spotted on Saturn by NASA’s Cassini spacecraft.

On Wednesday [May 24,2017], NASA released new images of Saturn’s north polar region, which has changed color in the last four years, possibly because summer has reached the northern hemisphere.

In the final stages of Cassini’s mission, which ends in September, it has shifted to a looping elliptical orbit, which will enable similar probing of Saturn’s interior.

“Eventually we will compare,” Dr. Bolton said. “We will really be able to advance our understanding of how these giant planets work.”

[1] Kenneth Chang, “NASA’s Jupiter Mission Reveals the ‘Brand-New and Unexpected’”, New York Times (May 25, 2017). A version of this article appears in print on May 26, 2017, on Page A20 of the New York edition with the headline: “Seeing the ‘Brand-New and Unexpected’ of Jupiter.”

Where Is Everybody?

Where Is Everybody?[1]

Perhaps my favorite essay in Aliens: The World’s Leading Scientists on the Search for Extraterrestrial Life is by the astrobiologist Lewis Dartnell, who patiently explains why aliens would not come here to have sex with us or eat us for supper.

I can only assume that he gets these questions a lot.

Here are the answers, should you find these possibilities concerning: The likelihood that we’d be genetically compatible with aliens is terribly remote, which means that they’d almost certainly be immune to our sexual charms. For similar reasons, having to do with biochemistry, we’d be lousy refreshments for them—they would almost certainly lack the proper enzymes to digest us.

As a bonus, Dartnell goes on to reassure us why aliens wouldn’t be especially interested in raiding our planet for raw materials, either (asteroids are a far easier source to mine); and if it were water they were after, they’d be far better off going to Europa, one of Jupiter’s largest moons, which contains more water beneath its icy shell than all the oceans on Earth combined.

If you’re interested in non-Earthly life, don’t look to the movies, is his point.

You could argue that that’s the general point of this modest, eccentric collection. Jim Al-Khalili, a quantum physicist and the editor of Aliens, opens with a question asked by Enrico Fermi in 1950: If the universe is so vast, and its age so old, and its stars so plentiful, where is everybody?

I’m no marketing expert, but “Where Is Everybody?” strikes me as a far catchier title for this book than the one it has, and it’s definitely more accurate. There really is nobody—so far—to write about. (Fighting words, I know. My hands hovered, spaceshiplike, for several minutes over the keyboard before committing that sentence to print.) This doesn’t mean that life elsewhere doesn’t exist. But it probably corresponds very little to what most of us have in mind, and not at all to the ooze-covered beasts of Ridley Scott’s electric dreams[2].

One of the most consistent takeaways from this anthology is just how banal extraterrestrial life might be. Often, when entertaining the possibility of aliens, what we’re really entertaining is the possibility of hardy microbes that can withstand extreme conditions, whether they’re thermophiles (heat lovers), psychrophiles (cold lovers) or halophiles (salt lovers). Read enough of Aliens, and you realize that the search for life is just as much about the most mundane aspects of biology as about the trippier questions of cosmology.

But it is also about philosophy. In this search, it helps to know what life is. Yet there’s no consensus about how to answer this question, strangely. (At the risk of being too Clintonian, it depends on what your definition of “is” is.)

Nor do we know how life began. At some point, the Earth made the transition from chemistry to biology, yes, but we cannot “agree on a definition that separates the nonliving chemistry from life,” as the geneticist Johnjoe McFadden puts it. (He then paraphrases the astronomer Fred Hoyle, who famously said that the odds of assembling something like a bacterium out of the primordial ooze were akin to the odds of a tornado’s assembling a jumbo jet out of a junkyard heap as it sweeps through.)

There are scientists who will go so far as to say that life is a spectacular fluke. Not everyone, mind you: Researchers now estimate that there are one billion Earthlike exoplanets in the Milky Way. “To my mathematical brain, the numbers alone make thinking about aliens perfectly rational,” Stephen Hawking has said.

But a powerful essay by the evolutionary biologist Matthew Cobb will make you wonder whether any form of multicellular life is far less likely than one in a billion. He points out that “there are more single-celled organisms alive on Earth than there are Earthlike planets in the observable universe”; that the number of single-celled organisms that have lived on this planet over the course of 3.8 billion years is beyond calculation; that these organisms have interacted “gazillions” of times (I love it when words of the appropriate magnitude desert even the experts). Yet we’ve never had a second instance of eukaryogenesis—that remarkable moment when one unicellular life form lodged inside another, forming something much more complex—in all this time.

Of course, there are researchers who dispute this theory and Cobb’s reasoning. But you get the idea.

The experience of reading almost any anthology is a bit like traveling across the country in a rental car with only an FM radio for company. Sometimes you get Sinatra; other times you get Nickelback.

This collection has its share of Nickelback. One of its most disappointing essays is about aliens in science fiction, which manages, against stupefying odds, to contain just one interesting insight: that authors tend to be more concerned with physics than with biology. (How did those gigantic sandworms evolve on the desert planet in Dune?)

But the best of these essays are far out in more ways than one. The very first, by the cosmologist Martin Rees, notes that our best hope for interstellar travel isn’t as humans, who don’t live very long and require far too much fuel to get very far, but as post-humans, who will have made the Kurzweilian transition from organic to inorganic, from decaying mortals to silicon-based, eminently portable machines. He adds that alien intelligence, if we ever detect it, will also be in this form.

The final essay, by Seth Shostak, a senior astronomer at the SETI institute (short for Search for Extraterrestrial Intelligence), goes even further, saying that if we really want to be attuned to alien life in the cosmos, it’s so likely to be in the form of machine intelligence that we ought to “be alert to apparent violations of physics.”

These forms of life may well be speaking to us even now. It’s just that our radio telescopes, which listen to the skies for signals from alien beings, can’t understand what they’re hearing. “Even if the search succeeded,” Rees writes, “it would still in my view be unlikely that the ‘signal’ would be a decodable message.”

It’s a whole new twist on George Berkeley’s question. The tree would fall in the forest. We’d hear it. But it would sound nothing like a tree.

[1] See Jennifer Senior, “‘Aliens’ Asks: If the Universe Is So Vast, Where Is Everybody?”, New York Times (May 24, 2017). This article is  review of the book: Al-Khalili, Jim(2007). ALIENS :The World’s Leading Scientists on the Search for Extraterrestrial Life. New York: Picador. Follow Jennifer Senior on Twitter: @jenseniorny. A version of this review appears in print on May 25, 2017, on Page C2 of the New York edition with the headline: “I Think It’s Gonna Be a Long, Long Time.” Downloaded May 26, 2017

[2] Scott is a South African born movie director of sci-fi films, including Alien, and The Martian.