Astronomy

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 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.

 

See Five Planets Together. Five!

Hello, old blog. Here’s some interesting astronomy news. Beginning tomorrow, January 20, and continuing until February:

“For the first time in more than 10 years, it will be possible to see all five bright planets together in the sky. Around an hour or so before sunrise, Mercury, Venus, Mars, Jupiter and Saturn, the five planets that have been observed since ancient times, will appear in a line that stretches from high in the north to low in the east.”

allfivebrigh

Here’s the full article from phys.org

All Five Bright Planets Come Together in the Morning Sky
January 15, 2016 by Tanya Hill, Museum Victoria, The Conversation

For the first time in more than 10 years, it will be possible to see all five bright planets together in the sky. Around an hour or so before sunrise, Mercury, Venus, Mars, Jupiter and Saturn, the five planets that have been observed since ancient times, will appear in a line that stretches from high in the north to low in the east.

The planets are visible from right across Australia in the dawn sky. You can start to look for the lineup from Wednesday, January 20 and it can be seen right through until the end of February.

Venus, Mars, Jupiter and Saturn have been in the morning sky since the beginning of the year. Jupiter is bright in the north, next comes reddish Mars, followed by pale Saturn and lastly brilliant Venus, which shines above the eastern horizon. It is the appearance of Mercury that makes the family complete.

Mercury has just transitioned from an evening object to a morning object. At first it will appear quite low to the eastern horizon and of all the planets it is also the faintest, so it will be hard to see to begin with. However, Mercury will continue to rise higher each morning and by early February it will sit just below bright Venus.

Dates with the moon

If you need something a little more to get you leaping out of bed before sunrise, then here are the dates to mark in your calendar. From the end of January, the moon will travel by each planet and can be used as an easy guide for your planet-spotting.

On January 28, the moon will be right next to Jupiter. Come February 1, the moon (in its Last Quarter phase) will be alongside Mars, then on the following morning it’ll sit just below the red planet. On the morning of February 4, the crescent moon will be near Saturn. Then on February 6, the moon will be alongside Venus and on February 7, a thin sliver of moon will sit below Mercury.

In line with the sun

The line formed by the planets in the sky closely follows the ecliptic, the apparent path of the sun against the background stars. This path marks the plane of our solar system, visual proof that the planets, including Earth, all orbit the sun on roughly the same plane.

The ecliptic is bordered by the constellations of the zodiac and one of the most recognisable zodiac constellations is Scorpius. If you’re awake before the first rays of the sun begin to drown out the stars, then look for the curved outline of the scorpion between Mars and Saturn. In fact, sitting just above Saturn is the red supergiant star Antares, which marks the heart of the scorpion and its reddish colour makes it the perfect rival for Mars.

Rare oddity

It’s been a long time since the orbits of all five planets have brought them together to the same patch of sky. To make the best of the viewing opportunity try and get to a clear open space where you can see from the north all the way across to the eastern horizon.

As early February comes around, I also highly recommend checking out the flight path of the International Space Station via websites such as Heavens Above or NASA’s Spot the Station.

The Station will be flying morning passes over Australia during that time and current predictions for each capital city have it travelling right through or near the line of planets, for example: Darwin (February 3), Brisbane (February 5), Perth (February 6), Sydney (February 7), Canberra (February 7), Adelaide (February 8), Melbourne (February 9) and Hobart (February 11). The predictions can change slightly, so best to check the websites closer to the date and be sure to enter your precise location to obtain the most accurate timing for the pass.

Finally, there’s still more to come. This August the five planets will be together again, visible in the evening sky, so stay tuned for more planet watching in 2016.

We Are Stardust, We Are Golden

we are stardustNice piece by astronomer Ray Jayawardhana in yesterday’s New York Times, “Our Cosmic Selves.” He opens with the line from the Joni Mitchell song that provided me with the epigraph for THE NIGHT OF THE COMET:

“We are stardust, we are golden,
We are billion-year-old carbon,
And we’ve got to get ourselves back to the garden.”

He goes on to discuss how we are all, indeed, made of “star dust”:

“By now, ‘stardust’ and ‘star-stuff’ have nearly turned cliché. But that does not make the reality behind those words any less profound or magical: The iron in our blood, the calcium in our bones and the oxygen we breathe are the physical remains — ashes, if you will — of stars that lived and died long ago.”

Here’s the whole piece, for your reading and intellectual pleasure this Easter weekend. Enjoy!

Our Cosmic Selves
APRIL 3, 2015
By RAY JAYAWARDHANA

JONI MITCHELL beat Carl Sagan to the punch. She sang “we are stardust, billion-year-old carbon” in her 1970 song “Woodstock.” That was three years before Mr. Sagan wrote about humans’ being made of “star-stuff” in his book “The Cosmic Connection” — a point he would later convey to a far larger audience in his 1980 television series, “Cosmos.”

By now, “stardust” and “star-stuff” have nearly turned cliché. But that does not make the reality behind those words any less profound or magical: The iron in our blood, the calcium in our bones and the oxygen we breathe are the physical remains — ashes, if you will — of stars that lived and died long ago.

That discovery is relatively recent. Four astrophysicists developed the idea in a landmark paper published in 1957. They argued that almost all the elements in the periodic table were cooked up over time through nuclear reactions inside stars — rather than in the first instants of the Big Bang, as previously thought. The stuff of life, in other words, arose in places and times somewhat more accessible to our telescopic investigations.

Since most of us spend our lives confined to a narrow strip near Earth’s surface, we tend to think of the cosmos as a lofty, empyrean realm far beyond our reach and relevance. We forget that only a thin sliver of atmosphere separates us from the rest of the universe.

But science continues to show just how intimately connected life on Earth is to extraterrestrial processes. In particular, several recent findings have further illuminated the cosmic origins of life’s key ingredients.

Take the element phosphorus, for example. It is a critical constituent of DNA, as well as of our cells, teeth and bones. Astronomers have long struggled to trace its buildup through cosmic history, because the imprint of phosphorus is difficult to discern in old, cool stars in the outskirts of our galaxy. (Some of these stellar “time capsules” contain the ashes of their forebears, the very first generation of stars that formed near the dawn of time.)

But in a paper published in December in The Astrophysical Journal Letters, a research team reported that it had measured the abundance of phosphorus in 13 such stars, using data taken with the Hubble Space Telescope. Their findings highlight the dominant role of so-called hypernovae, explosions even more energetic than supernovae that spell the demise of massive stars, in making the elements essential for life.

More than just atoms were produced in the celestial realm. Growing evidence suggests that interstellar space was also where atoms united to make some molecules pertinent for life. A study published last fall in Science, for example, used computer simulations to establish the provenance of Earth’s water. Its surprising verdict: Up to half the water on our planet is older than the solar system itself. Ancient water molecules assembled in the chilly confines of a gigantic gas cloud. That cloud spawned our sun and the planets that orbit it — and somehow those ancient water molecules survived the perils of the planetary birth process to end up in our oceans and, presumably, our bodies.

Such interstellar clouds may have been well suited for brewing a multitude of molecules. Last fall, in another study published in Science, a research team reported the first discovery in a stellar nursery of a carbon-bearing molecule with a “branched” structure. The detection of this molecule, the researchers wrote, “bodes well” for the presence in interstellar space of amino acids, for which a branched structure is a defining feature. (The researchers made use of a vast, partially operational network of radio dishes being erected on a high-altitude plateau in northern Chile, whose location makes it easier for radio emissions to reach us from the coldest bits of the galaxy, where the alchemy of life is presumed to have begun.)

Astrochemists are excited by this discovery because amino acids, which have been found already in some meteorites, form the basis of proteins. Meanwhile, last month, NASA scientists reported the creation of key DNA components in a laboratory experiment that simulated the space environment. Together, these findings raise the odds that life’s building blocks were concocted in space and blended into the material that formed Earth and its planetary siblings.

Amid the material comforts and the relentless distractions of modern life, the universe at large may appear remote, intangible and irrelevant, especially to those of us who are city dwellers. But the next time you catch a glimpse of the Milky Way in its true glory, from a dark outpost far from city lights, think of those countless stars as nuclear factories and the starless hazy patches as molecular breweries. It is not much of a stretch to imagine the inchoate seeds of life emerging in the distance.

Comet Siding Spring: Once in a Million Years

Astronomers are excited about Comet Siding Spring’s very close encounter with Mars this coming Sunday. Siding Spring was spotted back in January 2013. An Oort Cloud comet, it’s said to be the size of a small mountain, with a million-year orbit. A posse of spacecraft and Mars rovers are jockeying into position right now to observe it. Here on Earth, the comet will be visible with binoculars in the Southern Hemisphere.

How close will Comet Siding Spring come to Mars? 83,000 miles–which in space distances is a hair’s breadth, about a third of the distance between here and the Moon. Last year, before they’d plotted out its trajectory, astronomers were genuinely worried that the comet might hit Mars.

Its trajectory is such that it’ll never get closer to the Earth than some 83 million miles, so no need to panic yet. Of course, passing that close to Mars, there’s a possibility that Siding Spring might upset the Red Planet’s orbit, throwing the whole solar system out of whack, in which case, well . . . Best not to think about that.

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