George

Arrivederci, Cassini

Saturn’s rings captured by Cassini on Wednesday. Credit NASA/JPL-Caltech/Space Science Institute

CASSINI VANISHES INTO SATURN, ITS MISSION CELEBRATED AND MOURNED

New York Times
By KENNETH CHANG
SEPT. 14, 2017

PASADENA, Calif. — NASA’s Cassini spacecraft, the intrepid robotic explorer of Saturn’s magnificent beauty, ended a journey of 20 years on Friday like a shooting star streaking across Saturn’s sky.

By design, the probe vanished into Saturn’s atmosphere, disintegrating moments after its final signal slipped away into the background noise of the solar system. Until the end, new measurements streamed one billion miles back to Earth, preceded by the spacecraft’s last picture show of dazzling sights from around our sun’s sixth planet.

“The signal from the spacecraft is gone and, within the next 45 seconds, so will be the spacecraft,” Earl Maize, the program manager, announced in the control room at NASA’s Jet Propulsion Laboratory here, just after 4:55 a.m. local time.

His eyes teared and his voice wavered as he said, “I am going to call this the end of mission.” During a news conference later, he said, “To the very end, the spacecraft did everything we asked.”

The team members, some of whom had spent decades on the mission, started hugging each other when news of the spacecraft’s demise arrived.

Never again would Cassini send home the images and data that inspired discoveries and wonder during the probe’s 13 years in orbit around the ringed planet.

“For me, there’s a core of sadness, in part in thinking of the breakup of the Cassini family,” said Linda Spilker, Cassini project scientist. “But it’s both an end and a beginning as these people go off and work on other things.”

The mission for Cassini, in orbit since 2004, stretched far beyond the original four-year plan, sending back multitudes of striking photographs, solving some mysteries and upending prevailing notions about the solar system with completely unexpected discoveries.

“Cassini is really one of those quintessential missions from NASA,” said Thomas H. Zurbuchen, NASA’s associate administrator for science. “It hasn’t just changed what we know about Saturn, but how we think about the world.”

Cassini’s hazy origin story

Cassini had its origins in the brainstorm of two scientists, Daniel Gautier of the Paris Observatory and Wing-Huen Ip, then at the Max Planck Institute for Aeronomy in Germany.

NASA’s two Voyager spacecraft flew through the Saturn system in 1980 and 1981. Voyager 1, in particular, provided a close-up look at Titan that was enthralling and maddening. Larger than the planet Mercury, Titan was enshrouded in haze. The atmosphere was thicker than Earth’s and contained methane and other carbon-based molecules. What lay below, no one knew.

“Those discoveries led to many more questions,” Dr. Ip recalled.

In 1982, Dr. Gautier and Dr. Ip proposed to the European Space Agency that it collaborate with NASA on a Saturn mission: an orbiter paired with a probe that would parachute onto Titan.

The orbiter became Cassini, built and operated by NASA; the Titan probe was named Huygens, a project of the European Space Agency. The Europeans approved Huygens in 1988. A year later, NASA gave the go-ahead for Cassini. The craft were named for a Dutch astronomer, Christiaan Huygens, who discovered Titan and figured out Saturn had rings, and Giovanni Domenico Cassini, a French-Italian astronomer, who discovered four other major moons of Saturn, each in the 17th century.

To take advantage of the gravitational boost from a flyby of Jupiter to accelerate Cassini-Huygens, the spacecraft was launched on Oct. 15, 1997.

Discovering an Earthlike alien moon

Seven years later, Cassini swung into orbit around Saturn. A few months later, Huygens headed to its rendezvous with Titan, the first attempt to touchdown on a moon other than our own.

The lander was equipped with instruments to identify molecules in the air, measure the winds and haze, and take pictures on the way down.

Because the spacecraft designers did not know what the surface was made of, they had designed Huygens to handle several possibilities, including floating for a few minutes if it had turned out that Titan’s surface was a global ocean of methane.

Instead, Huygens bumped onto solid ground, surrounded by a complex network of small rivers. “If you would jump from your table or your desk, you would land on the floor at this speed,” said Jean-Pierre Lebreton, the project scientist for Huygens. “A very reasonable landing speed.”

Photographs at the surface showed what looked like rounded cobblestones that turned out to be blocks of water ice.

The data from Huygens, together with that gathered by Cassini in repeated flybys, revealed Titan as a world shaped by active geological processes with rivers, lakes and rain. But in the frigid temperatures there, about minus 290 degrees Fahrenheit, the fluid is not water, but methane. “Titan has really revealed an Earthlike world,” Dr. Lebreton said.

A journey toward disintegration

NASA spacecraft, if they survive to their destination, often just keep going.

Cassini stayed seven more years to watch changes in Saturn through the passing of seasons. It takes Saturn 29.5 years to orbit the sun, so Cassini has been there for almost half a Saturn year.

One of the mission’s most surprising discoveries was an ocean of water beneath the icy exterior of Enceladus that may be heated by hydrothermal vents similar to those at the bottom of oceans on Earth. The water on this moon and the carbon compounds it contains are some of the key ingredients needed for life that scientists would have thought unlikely on a moon just 313 miles wide.

Even at the end, 20 years after launch, Cassini and its instruments remained in good working shape. The plutonium power source was still generating electricity. But there was not enough propellant fuel left to safely send Cassini anywhere except into Saturn.

Any spacecraft, even one launched two decades ago, has unwanted microbial hitchhikers aboard. In particular, planetary scientists wanted to ensure that there was zero chance of the spacecraft crashing into and contaminating Enceladus or Titan, which could also be hospitable for life. And NASA wants to leave the Saturn system pristine.

In the very last phase of the mission, Cassini dove through the gap between Saturn and the planet’s innermost ring. That provided new, sharp views of the rings and allowed the craft to probe the planet’s interior, as another NASA spacecraft, Juno, is doing at Jupiter.

The last photographs taken by Cassini started streaming back to Earth on Thursday. An infrared image marked the spot high above the planet’s cloud tops where Cassini would disintegrate hours later.

Once these had been sent back to Earth, the probe was reconfigured for the final plunge.

Usually, Cassini would make observations, store them in its memory and beam them back to Earth later. This time, there would be no later. Instead, on the final plunge, the spacecraft kept its antenna dish pointed at Earth, as its instruments gave scientists their deepest direct look ever into Saturn.

As it moved into Saturn’s atmosphere, the drag of gas molecules started twisting the spacecraft, and its small thrusters could no longer keep the 30-passenger school bus-sized craft upright.

Cassini tipped over, its antenna no longer pointing at Earth. That is when the signal disappeared, at an altitude of about 870 miles.

The spacecraft disintegrated at about 7:31 a.m. Eastern time, and much of it melted quickly. The most resilient bits were probably the casings around its plutonium power source, designed to withstand re-entry into Earth’s atmosphere or an explosion at launch.

Studying final signals

Dr. Ip, who helped propose the mission in the 1980s, flew from Taiwan, where he is now a professor at National Central University, to join a commemoration of Cassini’s end at the California Institute of Technology. Hundreds of people gathered for what was part reunion, part celebration, part wake. In the predawn hours of Friday, he and his family were watching the mission’s final moments on giant screens placed on the lawn.

When the signal disappeared, Dr. Ip’s daughter, Anita, cried and hugged her father. “It’s hard to explain,” she said. “It’s always been part of the family.”

Dr. Ip himself was more stoic and bemused. How was he feeling?

“Oh, fine,” he said.

Not far away, William S. Kurth, a University of Iowa physicist who oversaw one of Cassini’s scientific instruments, was looking at a brightly colored plot on his laptop. The final data had already made the journey from Saturn to Australia to Pasadena to Iowa and back again to his computer on the lawn. He pointed out the radio emissions Cassini measured as it had entered Saturn’s atmosphere.

It was less than 10 minutes after word of Cassini’s death, and Dr. Kurth had homework to do.

Meteor Showers for 2017

In the New York Times, a good rundown of upcoming meteor showers, plus notes on what comet each shower originates from. Right now is a good time to see the Perseids shower. Full text and link below.

“If you spot a meteor shower, what you’re really seeing is the leftovers of icy comets crashing into Earth’s atmosphere. Comets are sort of like dirty snowballs: As they travel through the solar system, they leave behind a dusty trail of rocks and ice that lingers in space long after they leave. When Earth passes through these cascades of comet waste, the bits of debris — which can be as small as grains of sand — pierce the sky at such speeds that they burst, creating a celestial fireworks display.

“A general rule of thumb with meteor showers: You are never watching the Earth cross into remnants from a comet’s most recent orbit. Instead, the burning bits come from the previous pass. For example, during the Perseid meteor shower you are seeing meteors ejected from when its parent comet, Comet Swift-Tuttle, visited in 1862 or earlier, not from its most recent pass in 1992.”


A photo of Halley’s comet during its closest approach to the inner solar system in 1986. The comet is the source of the Eta Aquariids meteor shower. Credit NASA

METEOR SHOWERS IN 2017 THAT WILL LIGHT UP NIGHT SKIES
By NICHOLAS ST. FLEUR
NEW YORK TIMES
AUG. 9, 2017

All year long as Earth revolves around the sun, it passes through streams of cosmic debris. The resulting meteor showers can light up night skies from dawn to dusk, and if you’re lucky you might be able to catch one.

If you spot a meteor shower, what you’re really seeing is the leftovers of icy comets crashing into Earth’s atmosphere. Comets are sort of like dirty snowballs: As they travel through the solar system, they leave behind a dusty trail of rocks and ice that lingers in space long after they leave. When Earth passes through these cascades of comet waste, the bits of debris — which can be as small as grains of sand — pierce the sky at such speeds that they burst, creating a celestial fireworks display.

A general rule of thumb with meteor showers: You are never watching the Earth cross into remnants from a comet’s most recent orbit. Instead, the burning bits come from the previous pass. For example, during the Perseid meteor shower you are seeing meteors ejected from when its parent comet, Comet Swift-Tuttle, visited in 1862 or earlier, not from its most recent pass in 1992.

That’s because it takes time for debris from a comet’s orbit to drift into a position where it intersects with Earth’s orbit, according to Bill Cooke, an astronomer with NASA’s Meteoroid Environment Office, who spoke to The New York Times last year.

The name attached to a meteor shower is usually tied to the constellation in the sky from which they seem to originate, known as their radiant. For instance, the Orionid meteor shower can be found in the sky when stargazers have a good view of the Orion constellation.

How to Watch
The best way to see a meteor shower is to get to a location that has a clear view of the entire night sky. Ideally, that would be somewhere with dark skies, away from city lights and traffic. To maximize your chances of catching the show, look for a spot that offers a wide, unobstructed view.

Bits and pieces of meteor showers are visible for a certain period of time, but they really peak from dusk to dawn on a given few days. That is when Earth’s orbit crosses through the thickest part of the cosmic stream. Meteor showers can vary in their peak times, with some reaching their maximums for only a few hours and others for several nights. The showers tend to be most visible after midnight and before dawn.

It also might be easier to spot a meteor shower with your naked eye. Binoculars or telescopes tend to limit your field of view. You might need to spend about half an hour in the dark to let your eyes get used to the reduced light. Stargazers should be warned that moonlight and the weather can obscure the shows. But if that happens, there are usually meteor livestreams like the ones hosted by NASA and by Slooh.

While the American Meteor Society lists dozens of meteor showers that could be seen, below you’ll find the showers that are most likely to be visible in the sky for the remainder of 2017, as well as significant meteor showers that already reached their peak this year.

The Perseids
Active between July 13 and Aug. 26. Peaks around Aug. 12.
The Perseids light up the night sky when Earth runs into pieces of cosmic debris left behind by Comet Swift-Tuttle. The dirty snowball is 17 miles wide and takes about 133 years to orbit the sun. Its last go-around was in 1992.

Usually between 160 and 200 meteors dazzle in Earth’s atmosphere every hour during the display’s peak. They zoom through the atmosphere at around 133,000 miles per hour and burst about 60 miles overhead.

The Orionids
Active between Aug. 25 and Nov. 19. Peaks around Oct. 22.
The Orionids are an encore to the eta Aquariid meteor shower, which peaked in May. Both come from cosmic material spewed from Halley’s Comet. Since the celestial celebrity orbits past Earth once every 76 years, these showers are your chance to view the comet’s leftovers until the real deal next passes by in 2061.

The Leonids
Active between Nov. 5 and Dec. 3. Peaks around Nov. 18.
The Leonids are one of the most dazzling meteor showers and every few decades it produces a meteor storm where more than 1,000 meteors can been seen an hour. The last time the Leonids were that strong was in 2002. Its parent comet is called Comet-Temple/Tuttle and it orbits the sun every 33 years.

The Geminids
Active between Nov. 30 and Dec. 17. Peaks around Dec. 13.
The Geminids, along with the Quadrantids that peaked in January, are thought to originate not from comets, but from asteroid-like space rocks. The Geminids are thought to have been produced by an object called 3200 Phaethon. The meteor shower can brighten the night sky with between 120 and 160 meteors per hour.

The Ursids
Active between Dec. 17 and Dec. 24. Peaks around Dec. 22.
The Ursids tend to illuminate the night sky around the winter solstice in the Northern Hemisphere. They only shoot around 10 to 20 meteors per hour. They appear to radiate from Ursa Minor, and come from Comet 8P/Tuttle.

The Quadrantids
Active between Dec. 28 and Jan. 12. Peaked around Jan. 3.
The Quadrantids give off their own New Years fireworks show. Compared with most other meteor showers, they are unusual because they are thought to have originated from an asteroid. They tend to be fainter with fewer streaks in the sky than others on this list.

The Lyrids
Active between April 16 and April 25. Peaked around April 22.
There are records from ancient Chinese astronomers spotting these bursts of light more than 2,700 years ago. They blaze through the sky at about 107,000 miles per hour and explode about 55 miles up in the planet’s atmosphere. This shower comes from Comet Thatcher, which journeys around the sun about every 415 years. Its last trip was in 1861 and its next rendezvous near the sun will be in 2276.

The Eta Aquariids
Active between April 24 and May 19. Peaked around May 7.
The Eta Aquariids are one of two meteor showers from Halley’s Comet. Its sister shower, the Orionids, will peak in October. Specks from the Eta Aquariids streak through the sky at about 148,000 miles per hour, making it one of the fastest meteor showers. Its display is better seen from the Southern Hemisphere where people normally enjoy between 20 and 30 meteors per hour during its peak. The Northern Hemisphere tends to see about half as many.

The Southern Delta Aquariids
Active between July 21 and Aug. 23. Peaked around July 30.
They come from Comet 96P Machholz, which passes by the sun every five years. Its meteors, which number between 10 and 20 per hour, are most visible predawn, between 2 a.m. and 3 a.m. It tends to be more visible from the Southern Hemisphere.

The Loyal Engineers Steering NASA’s Voyager Probes Across the Universe

The Loyal Engineers Steering NASA’s Voyager Probes Across the Universe
New York Times, Aug. 3, 2017

Good long feature in the New York Times about what remains of the 1970s Voyager Mission, the one that sent two probes, Voyager I and II, to explore the outer planets of our solar system. Link above, text below.

The Voyager probes have since left the heliosphere and entered interstellar space, creaking along with ancient on-board computers that have 235,000 times less memory and 175,000 times less speed than your average smartphone.

The mission control team has shrunk to a staff of 9, most past retirement age, who work out of a small rental suite in Altadena. They’ve forgone promotions and better jobs to keep monitoring the spacecraft.

Both Voyager spacecraft carry the famous “Golden Record,” a gold-plated copper disc engraved with a wide variety of Earth images, sounds, and spoken and written messages. Included on the discs are sounds from nature, songs of birds and whales, greetings in 55 languages, and human sounds like footsteps and laughter. Plus, music by Bach, Mozart, Beethoven, Stravinsky, Blind Willie Johnson, and Chuck Berry, playing “Johnny B. Goode.”

Golden Record:

Golden Record Cover:

“Today the Voyagers are 10 billion and 13 billion miles away, the farthest man-made objects from Earth. The 40th anniversary of their launch will be celebrated next month.”

The Loyal Engineers Steering NASA’s Voyager Probes Across the Universe

As the Voyager mission is winding down, so, too, are the careers of the aging explorers who expanded our sense of home in the galaxy.

By KIM TINGLEYAUG
NYT, Aug. 3, 2017

In the early spring of 1977, Larry Zottarelli, a 40-year-old computer engineer at NASA’s Jet Propulsion Laboratory in Pasadena, set out for Cape Canaveral, Fla., in his Toyota Corolla. A Los Angeles native, he had never ventured as far as Tijuana, but he had a per diem, and he liked to drive. Just east of Orlando, a causeway carried him over the Indian and Banana Rivers to a triangular spit of sand jutting into the Atlantic, where the Air Force keeps a base. His journey terminated at a cavernous military hangar.

A fleet of JPL trucks made the trip under armored guard to the same destination. Their cargo was unwrapped inside the hangar high bay, a gleaming silo stocked with tool racks and ladder trucks. Engineers began to assemble the various pieces. Gradually, two identical spacecraft took shape. They were dubbed Voyager I and II, and their mission was to make the first color photographs and close-up measurements of Jupiter, Saturn and their moons. Then, if all went well, they might press onward — into uncharted territory.

It took six months, working in shifts around the clock, for the NASA crew to reassemble and test the spacecraft. As the first launch date, Aug. 20, drew near, they folded the camera and instrument boom down against the spacecraft’s spindly body like a bird’s wing; gingerly they pushed it, satellite dish first, up inside a metal capsule hanging from the high bay ceiling. Once ‘‘mated,’’ the capsule and its cargo — a probe no bigger than a Volkswagen Beetle that, along with its twin, had nevertheless taken 1,500 engineers five years and more than $200 million to build — were towed to the launchpad.

By T-minus two hours, a select few engineers, too nervous to sit down, stood at computers outside the high bay, overseeing the spacecraft telemetry. Elsewhere in the hangar, scientists, NASA brass from Washington and several dozen ‘‘nonessential’’ engineers — Zottarelli among them — huddled around TV monitors. At T-minus 30 seconds, the spacecraft’s engines roared to life, and many of the nonessentials took off running out of the room and toward the exit — ‘‘seven, six, five.’’ They burst out into the morning. Shielding their eyes, they peered across a flat expanse at smoke billowing on the horizon. Slowly and silently, the capsule rose out of the cloud, its rockets trailing flames. In an instant, there came a terrific boom as the sound waves from blastoff hit the hangar like a gong, ringing it as the spacecraft disappeared.

Two weeks later, after the second launch, everyone headed home. The show was over — both spacecraft were performing flawlessly — but behind the scenes, the mission, on a tight budget, lagged in hiring the more than 200 computer engineers needed to shepherd the spacecraft through a planetary encounter. Many of those on the flight team were fresh out of college, running the most sophisticated electronics systems in the world. They had barely had a chance to jell, when, in April 1978, not yet halfway to Jupiter, Voyager 1 experienced a problem. Its scan platform, where the cameras and instruments are mounted, got stuck.

As the engineers scrambled to figure out what they could do from more than 100 million miles away, someone forgot to send a weekly command to reset a timer on the other spacecraft. When it ran down without hearing from Earth, it triggered so-called fault-protection software, 600 lines of code that respond to malfunctions automatically. In this instance, fault protection assumed the radio receiver was broken and switched to the backup. On the mission-control monitors in a situation like this, the crawl of numbers reporting the status of the receivers would have turned crimson: a ‘‘red alarm.’’

Realizing their mistake, the engineers tried to stop the fault-protection routine, but the newly awakened backup receiver would not register their command. Helpless, they waited for the spacecraft to reason its way back to the original receiver; when it did, and the command went through normally, they were giddy with relief. They were still high-fiving when the working receiver shorted out like a blown fuse. Now it really was dead.

Fortunately, the malfunctioning backup receiver was still drawing current. They guessed that its oscillator, which allows it to accept a wide range of frequencies, had quit, essentially shrinking the target for transmissions from Earth. Assuming a much narrower bandwidth, and manually subtracting the Doppler effect, they recalibrated their signal. It worked — but to this day, the same calculation must precede every command. The original receiver remains useless: one engineer’s simple oversight nearly doomed humankind’s lone visit to Uranus and Neptune. ‘‘You like to think you have checks and balances,’’ Chris Jones, JPL’s chief engineer, who designed Voyager’s fault protection, told me. ‘‘In reality, we all worry about being that person.’’

Today the Voyagers are 10 billion and 13 billion miles away, the farthest man-made objects from Earth. The 40th anniversary of their launch will be celebrated next month. We tend to think of space as vacant, but it is actually matter, created, as everything in the universe is, by the explosions of ancient stars. Within our planetary neighborhood, this ‘‘space’’ is made up of different particles than the space outside is, because of supersonic wind that blows out from the surface of our sun at a million miles per hour. The wind generates a bubble around our solar system called the heliosphere. Five years ago, Voyager 1 reached the boundary where the heliosphere gives way to interstellar space, a region as novel to us — and potentially relevant — as the Pacific was to Europeans 500 years ago. The data the probes are collecting are challenging fundamental physics and will provide clues to the biggest of questions: Why did our sun give birth to life only here? Where else, within our solar system or others, are we most likely to find evidence that we are not alone?

The mission quite possibly represents the end of an era of space exploration in which the main goal is observation rather than commercialization. In internal memos, Trump-administration advisers have referred to NASA’s traditional contractors as ‘‘Old Space’’ and proposed refocusing its budget on supporting the growth of the private ‘‘New Space’’ industry, Politico reported in February. ‘‘Economic development of space’’ will begin in near-Earth orbit and on the moon, according to the president’s transition team, with ‘‘private lunar landers staking out de facto ‘property rights’ for Americans on the moon, by 2020.’’

All explorations demand sacrifices in exchange for uncertain outcomes. Some of those sacrifices are social: how many resources we collectively devote to a given pursuit of knowledge. But another portion is borne by the explorer alone, who used to be rewarded with adventure and fame if not fortune. For the foreseeable future, Voyager seems destined to remain in the running for the title of Mankind’s Greatest Journey, which might just make its nine flight-team engineers — most of whom have been with the mission since the Reagan administration — our greatest living explorers. They also may be the last people left on the planet who can operate the spacecraft’s onboard computers, which have 235,000 times less memory and 175,000 times less speed than a 16-gigabyte smartphone. And while it’s true that these pioneers haven’t gone anywhere themselves, they are arguably every bit as dauntless as more celebrated predecessors. Magellan never had to steer a vessel from the confines of a dun-colored rental office, let alone stay at the helm long enough to qualify for a senior discount at the McDonald’s next door.

Their fluency in archaic programming languages will become only more crucial as the years go on, because even as the probes harvest priceless information from the cosmos, they are running out of fuel. (Decaying plutonium supplies their power.) By 2030 at the latest, they will not have enough juice left to run a single experiment. And even that best case comes with a major caveat: that the flight-team members forgo retirement to squeeze the most out of every last watt.

One of the greatest obstacles to planetary science has always been the human life span: Typically, for instance, a direct flight to Neptune would take about 30 years. But in the spring of 1965, Gary Flandro, a doctoral student at Caltech, noticed that all four outer planets — Jupiter, Saturn, Uranus and Neptune — would align on the same side of the sun in the 1980s. If a spacecraft were launched in the mid- to late 1970s, it could use the gravity of the first body to slingshot to the second, and so on. Such a trajectory would add enough speed to shorten the total journey by almost two-thirds. What’s more, this orbital configuration would not appear again for 175 years.

The Voyagers carried cameras and instruments for analyzing atmospheric temperatures, moon masses, gravitational and magnetic fields and radiation levels. Reaching Jupiter in 1979, they captured images of lightning in its cloud tops and astounded scientists — who had assumed all moons were as barren as our own — with pictures of eight active volcanoes on its satellite Io; Europa, another Jovan moon, was encased in a shell of water ice, cracked in places by what appeared to be the tides of an ocean below. The photographs revealed themselves on control-room monitors pixel by pixel, row by row. ‘‘I would be sitting in here at night sometimes when the Voyager mission was flying,’’ Esker Davis, project manager for the Saturn encounter, told David W. Swift, who published an oral history of the mission in 1997, after Davis’s death. ‘‘And my wife would call up and ask what I was doing. I said, ‘Just watching pictures come in, being the first person to see this picture.’ ’’

The mission would have ended there, but President Ronald Reagan bestowed an extension, possibly swayed by the real-time briefings hosted by Ed Stone, the project’s lead scientist, on the occasion of every planetary encounter. Hundreds of reporters, as well as politicians and celebrities, attended, packing into a cramped JPL auditorium for the debuts of Uranus in 1986 and Neptune in 1989.

The final flyby, of Neptune’s moon Triton, took place on a hot August night. Afterward, everyone celebrated with Champagne, cold cuts and drunken singing; on the JPL lawn, Chuck Berry performed ‘‘Johnny B. Goode,’’ one of the tracks included on gold-plated records of human sights and sounds attached to the spacecraft for any intelligent life that might find them. Then, gradually, the hallways grew quiet. Stone and his colleagues moved on to new projects while analyzing Voyager data part time; the flight team laid off 150 engineers (many of whom went on to staff subsequent missions). The probes’ new goal was to reach interstellar space. But though scientists had measured the speed of the solar wind that forms the heliosphere, the properties of the matter beyond it had never been analyzed. How much pressure it exerted on the bubble, and thus the size of the bubble, were a mystery. So, too, was how long — years? decades? — it might take a craft to escape it.

At the mission’s outset, the flight-team members were mischievous kids. They relieved stress with games and pranks: bowling in the hallway, using soda cans as pins; filling desk drawers with plastic bags of live goldfish; making scientists compete in disco-pose contests. Now, by 1990, they were older, with kids of their own. They had experienced the deaths of colleagues and watched others’ marriages falter as a result of long hours at the lab. With no planets to explore, they spent the decade doing routine spacecraft maintenance with a fraction of their bygone manpower. Six of the current nine engineers were on the team then. Sun Kang Matsumoto, who joined the mission in ’85, studied so diligently to master the new roles pressed upon her that her sons learned the spacecraft contours by osmosis. When her eldest was 8, he surprised her with a perfect Lego model; now in college, ‘‘he calls and asks, ‘How is Voyager?’ Like, ‘How is Grandma?’ ’’ Matsumoto says.

The mission originally occupied three floors of Building 264 on the JPL campus, home to many of the lab’s highest-profile projects. But soon after Neptune, says Jefferson Hall, who joined the project in 1978, ‘‘we were booted out.’’ Their first move was into the former offices of a mainframe-computer company in Sierra Madre. In 2002, after more staff cuts, they moved to a rental suite in Altadena. NASA reviewed the mission to determine if it should be canceled altogether.

The scientists’ models, meanwhile, began to reveal subtle changes in the raw data. By late 2004, it was clear that Voyager 1’s magnetometer had detected an abrupt increase in the strength of the surrounding magnetic field, suggesting the probe had entered the outermost layer of the heliospheric bubble, the ‘‘heliosheath.’’ This is where the solar wind ions abruptly slow as they press outward against the surrounding interstellar matter and swerve to create a cometlike tail. A wind of interstellar ions flows around the outside of the bubble like water around the bow of a ship. Finally, on Aug. 25, 2012, the density of particles around the spacecraft precipitously increased, as though it had plunged from sky to sea. It had crossed the threshold of interstellar space.

In 2016, the year he turned 80, Zottarelli, the flight team’s most experienced programmer, gave six months’ notice and spent the time training a successor. None of the other engineers, only one of whom is under 50, have a replacement in waiting in the event that they abdicate more suddenly. Unlike the astrophysicists who devise experiments for Voyager and who interpret the results, the core flight-team members don’t have the luxury of being able to work simultaneously on other missions. Over decades, the crew members who have remained have forgone promotions, the lure of nearby Silicon Valley and, more recently, retirement, to stay with the spacecraft. NASA funding, which peaked during the Apollo program in the 1960s, has dwindled, making it next to impossible to recruit young computer-science majors away from the likes of Google and Facebook.

Last autumn, I drove through the San Gabriel Valley to a squat concrete building beside Scott-Fox Puppy Preschool. Suzanne Dodd, 56, the mission’s project manager, answered the door. She wore red-framed glasses over sharp blue eyes, and her fair hair was cut short. She escorted me past the vestibule to a common room ringed by office doors. Hanging over the cubicle partitions in the center was a shingle that read ‘‘Mission Control.’’

‘‘You can see where we are in the culture,’’ she said, with a mild sweep of her palm. Voyager was her first job. She pointed out a used microfiche reader that Tom Weeks, a hardware engineer and the self-described mission librarian, purchased on eBay to read old diagnostics reports. To conserve power on the spacecraft, the engineers must decide what to turn off when, and for how long — which means estimating how cold they can let each component get. (On Voyager 2, because of the broken oscillator, any change in temperature also tweaks the receiver frequency.) Turning the heaters off for a while is the safest way to get enough power to run the instruments, but the lower the overall wattage drops, the faster parts will freeze. One of the team’s most valuable insights so far: Spinning the wheels of an eight-track tape recorder — the spacecrafts’ only data-storage option — generates a bit of additional heat.

Enrique Medina, the power subsystem expert, was preparing to implement a ‘‘patch,’’ an update that would turn off a heater on Voyager 2 in order to run the gyroscope, roll the spacecraft and calibrate the magnetometer. Even though they simulate every patch with software, there is plenty of room for human error. Far more often, hardware fails for no evident reason. In 1998, Voyager 2 reacted to a command by going silent. For 64 hours straight, the flight team studied the specific instruction — consisting of 18 bits, or 1s and 0s — that preceded the blackout. Bits have been known to ‘‘flip’’ to the opposite value, changing the instruction the same way that swapping a single letter turns ‘‘cat’’ into ‘‘cut.’’ The question was: What instruction had they accidentally given and how could they undo it? At last, modeling the outcome of each possible bit, they discovered one that turned off the exciter, which generates the spacecraft’s radio signal; when they turned it back on, the transmissions resumed. A similar scare took place in 2010, when a bit involved in formatting telemetry flipped, turning the transmissions to gibberish. ‘‘A lot of our anomalies we’ve come up with workarounds for, and at the time we didn’t know why it happened,’’ Weeks explained. Dodd added, ‘‘The No. 1 rule with spacecraft is: Don’t change it if you don’t have to.’’

In the mission-control cubby, Medina, who is 68 and a grandfather of four, with a husky voice and a Tom Selleck mustache, rolled a chair over to two pairs of monitors labeled with construction-paper signs that read: ‘‘Voyager Mission Control Hardware, PLEASE DO NOT TOUCH.’’ He jiggled a mouse, and one of the screens woke to a stream of numbers and letters describing the health of Voyager 1.

Because they have only four kilobytes of computer storage, the spacecraft transmit data 24/7, but the radio signals take 19 hours and 12 hours to reach Earth. The three antenna dishes big enough to register them are shared, so Voyager gets only four to six hours of reception time per spacecraft per day; outside these often odd windows, their data dissipate into the ether. Medina gestured to another computer in the corner that monitors the telemetry that comes in when the office is empty and, if it detects an anomaly, phones an on-call engineer: the Voyager Alarm Monitor Processor Including Remote Examination tool. ‘‘We call it Vampire,’’ Medina said, ‘‘because it works in the middle of the night.’’

In March 2014, after news broke that Voyager 1 had crossed into interstellar space, I spoke with Medina over the phone. ‘‘I would not leave my wife to go with Angelina Jolie, as exciting as that sounds,’’ he told me. ‘‘And I would not leave Voyager to go to the new Mars missions. I will not leave Voyager until it ceases to exist. Or until I cease to exist.’’

All the billions of stars in the universe, hosts to billions of planets, have a heliosphere. Understanding the properties of our own will help us interpret observations of those systems. Voyager 1 has shown that it blocks 75 percent of cosmic radiation, which at extreme levels is toxic to life as we know it. This is not a static number: Our sun is orbiting the galaxy at 125 miles per second; its interstellar environment — and thus the size and shape of its heliosphere — is constantly in flux.

‘‘If the pressure outside got high enough, and there are some areas in the Milky Way galaxy where it would be high enough, it could compress the heliosphere down to where in fact the boundary is almost to where we are. And that would change the radiation environment of the planets, which is important when you want to try to understand anything about the origin of life,’’ Ed Stone, the science-team leader, told me when I visited him at Caltech last fall. ‘‘Here on Earth, wherever there’s liquid water, whether it’s boiling water coming out of the vents or frozen water, there are microbes there. So life is remarkably robust where there’s water.’’

He went on: ‘‘I think that one of the biggest questions is, Can we find a spot here in the solar system where there’s microbial life? If there’s no microbial life anywhere else, that would be surprising, given here on Earth it appeared fairly quickly after the end of the bombardment,’’ an epic rain of asteroids some four billion years ago. ‘‘If one could ever find some evidence of it here in the solar system where we could get a sample, then one could look at the DNA. All life on Earth has a related DNA. Is that true for everywhere? Either answer would be amazing. Either there’s only one way that life evolves, or no, there’s more than one way.’’

In his office, Stone stood on tiptoe to lift an intricate model of Voyager from the top of a bookcase. At 81, he moves more stiffly than the Stone of NASA archival footage. Otherwise, he is remarkably unchanged. On a bulletin board behind his computer, he pins the latest graphs of the rate of charged particles that each spacecraft has detected. A drastic dip in low-energy ones is what convinced him that Voyager 1 had exited the heliosphere, and he is eager for Voyager 2, which entered the heliosheath from a different angle in 2007, to see a comparable drop before it goes quiet.

‘‘When we started this, I realized we were on a mission of discovery,’’ he said. ‘‘I just had no idea how much discovery there was going to be. And I certainly had no idea that it would last as long as it has.’’ After we lose contact with them, the spacecraft will continue to orbit the galaxy for billions of years, never striking another star. ‘‘Space,’’ Stone said, ‘‘is really empty.’’

Astrophysicists who study the heliosphere wage a constant battle against apathy when it comes to invisible substances nearly 100 times farther away from us than the sun is. ‘‘I hear a lot of people saying, ‘So what?’ I try to explain: ‘It’s like your home,’ ’’ Merav Opher, a professor of astrophysics at Boston University and a member of the Voyager science team, told me. ‘‘You just found out the walls aren’t walls. They’re porous. I think it’s existential.’’ In 2006, Opher and Stone published a landmark paper in The Astrophysical Journal predicting that Voyager 2 would encounter the heliosphere boundary closer to the sun than its twin had, pointing to a startling contradiction: The heliosphere must be asymmetrical; it is not a ‘‘sphere’’ after all.

There is passionate disagreement about what its exact shape is. (The Voyager scientists argue over practically every scrap of data; a few holdouts insist that Voyager 1 has yet to reach interstellar space.) In 1961, Eugene Parker, the renowned astrophysicist who first predicted the existence of a heliosphere, hypothesized that it might look like a comet — compressed in front with a tail in back. Earlier this year, Tom Krimigis, the emeritus head of the Applied Physics Laboratory at Johns Hopkins University and the principal investigator for Voyager’s Low-Energy Charged Particle Experiment, published a paper in Nature Astronomy showing that the heliosphere has a very short tail and ‘‘kind of moves through space like a clenched fist.’’ His instrument has also shown that cosmic rays — expected to flow toward the heliosphere uniformly from across interstellar space — actually move quite differently depending on their orientation to the interstellar magnetic field. ‘‘Every once in a while, a tsunami passes Voyager,’’ Krimigis told me, referring to these waves. ‘‘The galaxy was supposed to be a calm sea, and that’s not what we find.’’

Opher believes that the influence of the sun’s magnetic field may warp the heliosphere into the shape of a ‘‘croissant.’’ At its plump center, interstellar matter presses in closer than previously thought — which would mean we are less isolated from the rest of the galaxy than we believe.

Last Sept. 29, a Thursday, Larry Zottarelli awoke before 7, as he did most weekdays, and dressed quietly so as not to disturb his sleeping wife. He raked a comb through his silver hair, donned trifocals and a calculator watch and drove to the office. He brewed his first mug of coffee in the efficiency kitchen and carried it to his desk. He’d been on the job for 40 years; the next day would be his last. A printed-out email taped to his computer hutch had instructions for handing in his badge and parking pass and collecting his final paycheck. He had cleared out most of his belongings, except two gallon-size Ziploc bags, in which he had sealed the plastic arms of his office chair to protect them from disintegrating under the daily weight of his elbows. Sitting facing the door, backed by a windowless, conch-pink brick wall, he brought to mind a hermit crab wearing a seashell.

Later that morning, when Zottarelli entered the conference room to attend his last daily flight-team briefing, his colleague Adans Ko, 58, was arranging takeout containers of dim sum on the table for a celebration. He threw an arm around his shoulders and said, ‘‘Larry is going to give me a kiss today!’’ Matsumoto, who was holding a camera, said, ‘‘O.K., look at me.’’ She was making a photo album for him. When the party broke up, I found Zottarelli’s replacement, Lu Yang, at her desk. I asked her if he had given her any specific advice. ‘‘Whatever the problem, you go there and solve it,’’ she said, and laughed.

In retirement, Zottarelli told me, he would like to see Florida again. He wonders how it has changed. In his garage is a 1954 Swallow Doretti, a fixer-upper. ‘‘It probably needs new brakes,’’ he said. I asked him if there was anywhere he liked to drive for fun. ‘‘No,’’ he replied. ‘‘Not anymore.’’

I had stopped by his office to say goodbye and ask him what he planned to do with his newfound freedom. I pictured him in the Doretti, flying down the Pacific Coast Highway, wind in his hair. But he seemed to be in no mood for talking. I wished him well and turned to go. Then he spoke. ‘‘I expect my second stroke will be on the 17th of November,’’ he said ruefully, gesturing toward his empty wall calendar. ‘‘Life expectancy is five to seven years at my age on retiring, so —’’ He paused. ‘‘That was humor, I guess. I’m not looking forward to being even older. Got no choice in the matter.’’

I asked if he ever found himself thinking about the billions of years that the Voyagers will circle the center of the galaxy, long after our sun has exploded, scattering more stardust throughout the universe. ‘‘Of course,’’ he said. ‘‘I was raised in the Roman Rite. I’m pretty much an atheist. But what is the meaning of life? It’s not Monty Python, O.K.?’’

Had he reached any conclusions about what it is? ‘‘Well, on Earth, yeah,’’ he said. ‘‘One species always prepares the way for the next generation — that’s all.’’

* * *

The Great Comet of 1861

The Great Comet of 1861 was “discovered” today, May 13, 1861, by John Tebbutt, a sheep farmer and amateur astronomer of Windsor, New South Wales, Australia.

(An impression of the great comet of 1861 as seen from Kent on the evening of June 30th. The Earth is believed to have passed through the comet’s tail on this day. Painting © Chris Chatfield.)

“The comet of 1861 was not the most spectacular of the nineteenth century (that probably being the comet of 1811) or the most beautiful, which was Donati’s of 1858, but its appearance was dramatic, and it interacted with the Earth in an almost unprecedented way. For a while the Earth was actually within the comet’s tail, and the inhabitants of this planet had a brief but giddy view of streams of cometary material converging towards the distant nucleus. By day also the Sun was dimmed as the Earth ploughed through the comet’s gas and dust.”

More about the Comet of 1861 here.  

Duck and Roll! Asteroid Coming!

An asteroid the size of the Rock of Gibraltar will graze past the Earth on April 19. At a distance of 1.1 million miles, there’s really no danger that it’ll hit us (so they say).


(This is not a picture of the actual Asteroid 2014-JO25; this is a random asteroid from the inter-verse.)

This reminds me that while the current White House administration (cough cough) has promised NASA funding to continue working on a mission to Mars, they’ve cut funding for the “Asteroid Redirect Mission.” According to the Huffington Post:

“That project would have included a robotic attempt to rendezvous with an asteroid, then collect and haul a giant boulder from it for future study by a manned crew. Part of this plan was also to redirect the asteroid’s trajectory away from any path that would bring it close to Earth.”

More here on asteroid capture and landing projects.

April Fool’s Day Comet

Really it’s named comet 41P/Tuttle-Giacobini-Kresák, but that doesn’t have the same ring to it, does it? This Saturday night, April 1, 2017, it’ll make its closest flyby of Earth since its discovery in 1858.

You’ll need a strong pair of binoculars or a telescope to see it. More about it here.

Tons of Cosmic Dust Everywhere

A recent New York Times article describes a cool phenomenon that gets a mention in THE NIGHT OF THE COMET:  the tons of cosmic dust that rain down on the Earth every day.  10 tons of it, every day.

These examples of space dust found on Earth are collected in a new book, “In Search of Stardust: Amazing Micro-Meteorites and Their Terrestrial Imposters,” and were found on buildings, parking lots, sidewalks and park benches. Credit Jan Braly Kihle/Jon Larsen.

Says the article:

“The dust consists of tiny remnants from the solar system’s birth, including debris from the lumps of dirty ice known as comets and from ages of smashups among planets and the big rocks known as asteroids. While most of the particles are interplanetary in nature, some contain grains of matter from outside the solar system, or true stardust . . .

“’Your car is covered with cosmic dust,’ Dr. Brownlee said. ‘We inhale this stuff. We eat it every time we eat lettuce. But normally, it’s incredibly difficult to find.'”

The article describes how one amateur scientist finally devised a way to find and photograph all this stuff.  Click on the above link in the title to read, or see the full text below. 

 

After decades of failures and misunderstandings, scientists have solved a cosmic riddle — what happens to the tons of dust particles that hit the Earth every day but seldom if ever get discovered in the places that humans know best, like buildings and parking lots, sidewalks and park benches.

The answer? Nothing. Look harder. The tiny flecks are everywhere.

An international team found that rooftops and other cityscapes readily collect the extraterrestrial dust in ways that can ease its identification, contrary to science authorities who long pooh-poohed the idea as little more than an urban myth kept alive by amateur astronomers.

Remarkably, the leader of the discovery team — and co-author of a recent paper in Geology, a monthly journal of the Geological Society of America — turns out to be a gifted amateur who devoted himself to disproving the skeptics.

A noted jazz musician in Norway, he rearranged his life to include eight long years of extraterrestrial sleuthing. His hunt has now produced a significant discovery, a colorful book for lay readers and what scientists call a portrait gallery of alien visitors.

“I hope and believe this will start something,” the musician, Jon Larsen, said in an interview. His goal? “Making it easy.”

His book, “In Search of Stardust: Amazing Micro-Meteorites and Their Terrestrial Imposters,” due out in August, details the secret of his extraordinarily successful hunts. Its 150 pages and 1,500 photomicrographs, or photos taken through a microscope, tell how Mr. Larsen taught himself to distinguish cosmic dust from the minuscule contaminants that arise from roads, shingles, factories, roof tiles, construction sites, home insulation and holiday fireworks.

As his book puts it, “To pick out one extraterrestrial particle among billions of others requires knowledge both about what to look for and what to disregard.”

The diminutive flecks to which Mr. Larsen, 58, has devoted himself represent the smallest parts of a cosmic downpour that has lashed the Earth for billions of years.

Careful observers of the night sky are familiar with shooting stars — speeding bits of extraterrestrial rock that plunge through the Earth’s atmosphere, often burning up completely. The biggest can strike the ground, some forcefully enough to dig craters. In 2013, a relatively small rock exploded over the Russian city Chelyabinsk, releasing a shock wave that injured hundreds of people, mainly as windows shattered into flying glass.

But all that represents a tiny fraction of the downpour. Scientists say most of the cosmic material is remarkably small — barely the width of a human hair. Known as micrometeorites, they rain down on the planet more or less continuously but have proved remarkably hard to find. Some bits are so small and lightweight that they drift down to the Earth’s surface without melting.

The dust consists of tiny remnants from the solar system’s birth, including debris from the lumps of dirty ice known as comets and from ages of smashups among planets and the big rocks known as asteroids. While most of the particles are interplanetary in nature, some contain grains of matter from outside the solar system, or true stardust. Their diversity makes them excellent windows on the cosmos.

Scientists have found micrometeorites mainly in the Antarctic, remote deserts and other places far from civilization’s haze. Starting in the 1940s and 1950s, investigators tried to find them in urban areas but eventually gave up because of the riot of human contaminants.

Significantly, it turns out that specialists trying to establish the cosmic origins of the tiny specks have tended to examine their chemical signatures rather than their overall appearance. That left a large opening for Mr. Larsen.

Matthew J. Genge, one of the Geology paper’s four authors and a senior lecturer in earth and planetary science at Imperial College, London, used an electron microprobe at the Natural History Museum in London to determine the chemical makeup of Mr. Larsen’s finds and confirm their cosmic origin.

In an interview, he said that, over all, the grains that survive the atmospheric plunge and land on the Earth’s surface add up to more than 4,000 tons annually, or more than 10 tons a day. “He’s done a valuable thing in classifying the contaminants,” Dr. Genge said of Mr. Larsen’s work. “It has wide-reaching implications.”

Donald E. Brownlee, an astronomer at the University of Washington who helped establish the field, called Mr. Larsen a true citizen scientist whose work will aid the global hunt for the tiny specks.

“Your car is covered with cosmic dust,” Dr. Brownlee said. “We inhale this stuff. We eat it every time we eat lettuce. But normally, it’s incredibly difficult to find.”

Mr. Larsen came to what he calls Project Stardust as a jazz guitarist in Norway, perhaps known best as the founder of Hot Club de Norvège, a string quartet. His group helped spur the global revival of gypsy jazz.

As Mr. Larsen tells the story, he was an enthusiastic rock collector as a child but did so well as a musician that he set aside his early scientific ambitions. Then, in 2009, at a country house outside Oslo, he was cleaning an outdoor table when a bright speck caught his eye.

“It was blinking in the sunlight,” he recalled. He touched the fleck. “It was angular in some way, kind of metallic but so small — a tiny dot.”

Intrigued, Mr. Larsen suspected it was a cosmic visitor and began to look for more. He collected dust samples from Oslo and cities around the globe, moonlighting as a scientist while vacationing or touring with his jazz group. He took samples from roads, roofs, parking lots and industrial areas.

Put indelicately, he collected hundreds of pounds of dreck — sludge from drains, gutters and downspouts, the dregs of civilization that most people try to avoid.

“Still, I didn’t find a single micrometeorite,” he recalled. “It was very frustrating.”

Mr. Larsen then changed tactics. Rather than looking exclusively for cosmic dust, he taught himself how to classify the dozens of different kinds of earthly contaminants, starting a process of elimination that slowly narrowed the candidates and raised the chances that some tiny fraction of the urban debris might turn out to belong to the cosmos.

The breakthrough came two years ago. In London, Dr. Genge studied one of the gathered particles — from Norway, not Timbuktu — and confirmed that it was indeed a traveler from outer space. Mr. Larsen quickly identified hundreds more.

“Once I knew what to look for, I found them everywhere,” he said.

In the Geology paper, the scientific team reports the discovery of about 500 micrometeorites — collected mainly from roof gutters in Norway — and tells of the detailed analysis of 48 of the extraterrestrial specks. The team includes two of Dr. Genge’s students, Martin D. Suttle of Imperial College and Matthias Van Ginneken of the Université Libre in Brussels.

The team described the cosmic dust as the youngest collected to date, because gutters tend to get cleaned fairly regularly. Also, urban surfaces are recent arrivals in the global landscape compared to polar ice and ancient deserts.

In his travels, Mr. Larsen recently visited with Michael E. Zolensky, an extraterrestrial materials scientist in Houston at the Johnson Space Center of the National Aeronautics and Space Administration. They not only talked shop but also went up to the roof of the large building that houses rocks from the Apollo moon program.

“It was pretty cool,” Dr. Zolensky said. “The curation building is now a collector of cosmic dust.”

In an interview, Mr. Larsen described his method — sorting through the contaminants in a process of elimination — as “something that anybody can do. It could and should become part of teachings in schools, an aspect of citizen science.”

Dr. Brownlee of the University of Washington agreed. He said that, while many schools try to find cosmic dust particles in programs meant to make science classes more inviting and accessible, few if any succeed. “It could help a lot,” he said of Mr. Larsen’s method. “For education, it’s pretty cool.”

Dr. Genge of Imperial College said Mr. Larsen’s techniques, if adopted widely, might also open a new lens on the cosmos.

The gravitational pull of the planets, he noted, appear to tug on the dust clouds of the solar system and slowly change their orbits. He said a wave of new terrestrial finds could help scientists better map the clouds, raising more questions for science about the structure of the universe.

“I consider my microscope a telescope,” Dr. Genge said. “It can give you a pretty big picture.”

 

An Eclipse, a Comet, and a Full Moon all Coming this Friday Night: Prepare for the Endtimes!

 

From USA Today.  Skywatchers will enjoy a rare space triple-header Friday night and early Saturday morning: A “penumbra” lunar eclipse during the full “snow” moon — and the flyby of a comet.

Here’s a look at what you will see if you set your eyes to the night sky:

Penumbral lunar eclipse

Eagle-eyed skywatchers will see a “penumbral” lunar eclipse Friday evening during the full moon.

Not as spectacular — or noticeable — as a total lunar eclipse, this rather subtle phenomenon occurs when the moon moves through the outer part of Earth’s shadow (known as the penumbra), according to EarthSky.org.

The outer shadow of the Earth blocks part — but not all — of the sun’s rays from reaching the moon, making it appear slightly darker than usual.

The exact moment of the penumbral eclipse is 7:43 p.m. ET (6:43 p.m. CT, 5:43 p.m. MT and 4:43 p.m. PT), NASA said.

The eclipse will be visible from Europe, Africa, western Asia and eastern North and South America, NASA reports.

About 35% of all eclipses are of the penumbral type.

Full “snow” moon

As required during any lunar eclipse, the moon will be full Friday night. And this month it’s nicknamed the “snow” moon.

According to the Farmers’ Almanac, full moon names date back to Native Americans in the northern and eastern U.S. Each full moon has its own name.

“The tribes kept track of the seasons by giving distinctive names to each recurring full moon,” the almanac reports. “Their names were applied to the entire month in which each occurred.”

Calling February’s full moon the “snow” moon is right on target: On average, February is the USA’s snowiest month, according to data from the National Weather Service.

The Farmer’s Almanac reports some tribes referred to February’s moon as the “hunger” moon, because harsh weather conditions made hunting difficult.

Comet 45P

A few hours after the eclipse, Comet 45P, which has been visible after sunset for the past two months through binoculars and telescopes, makes its closest approach to Earth, when it will be “only” 7.4 million miles away, NASA said.

Look to the east around 3 a.m. Saturday morning, where it will be visible in the sky in the constellation Hercules. Binoculars or a telescope could be helpful. Watch for a bright blue-green “head” with a tail.

It will be visible in various points of the night sky until the end of February, according to NASA. If you miss it, don’t worry: It will return again in 2022, said Jane Houston Jones of NASA’s Jet Propulsion Laboratory.

 

From “Record of the World’s Change”

“When a comet appears in the Constellation Hydra, there is war and some conspire to overthrow the emperor. Fish and salt are expensive. Rice also becomes expensive. People hate life and don’t even want to speak of it.” (Record of the World’s Change, Li Ch’un Feng, 602-667 AD)

Image from Das Wundereichenbuch (The Book of Miracles), Augsburg, 1550

LETTER TO MY DAUGHTER Taiwan Edition

I still quite like this cover on the Taiwan edition of LETTER TO MY DAUGHTER.

The holiday sale for the e-book continues for just a few more days. (English. Not Chinese.) Here are the links again:

Amazon
Barnes & Noble
iBooks