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A close pass of Comet Wirtanen in 2018 offered researchers an unprecedented opportunity.

Comets are full of surprises. Not only do they often under- or very occasionally over- perform versus expectations, but they also offer a glimpse of the remnants of the very early solar system. In December 2018, astronomers had an unprecedented opportunity to study one of these relics of the early solar system up close as Comet 46P/Wirtanen sped by Earth just 30 times the Earth-Moon distance (7.1 million miles away) on its closest passage for this century.

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The orbit of Comet 46P/Wirtanen. NASA/JPL

Discovered by astronomer Carl A. Wirtanen in 1948, short period Comet 46P Wirtanen orbits the Sun every 5.4 years, on a path that takes it from a perihelion 1.06 AU from the Sun to an aphelion of 5.13 AU, just outside the perihelion of Jupiter.

The 2018 approach past Earth for the comet was an especially favorable one, and this time, astronomers at the W.M. Keck Observatory on Maunakea, Hawai’i were ready. Keck’s Near Infrared Spectrograph (NIRSPEC) just received a major upgrade, featuring more pixels and higher sensitivity, an upgrade that would see first light obtaining spectra of the comet.

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Instruments need hugs, too. Dr. Emily Martin with the newly upgraded NIRSPEC instrument. W.M. Keck Observatory.

And the results, recently published in The Planetary Science Journal were a spectacular success. Not only did the team classify a list of key compounds seen out-gassing from Comet Wirtanen, but they discovered a high alcohol ratio for the comet, along with an anomalous heating mechanism at play.

“46P/Wirtanen has one of the highest alcohol-to-aldehyde ratios measured in any comet to date,” says Neil Dello Russo (JHU/APL) in a recent press release. “This tells us information about how carbon, oxygen, and hydrogen molecules were distributed in the early solar system where Wirtanen formed.”

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Findings from the recent NIRSPEC upgrade. Keck Observatory Astronomy Talk Video

The Keck study also noticed a continuous heating of cometary material sublimating through the coma, the familiar wreath of gas and dust surrounding the nucleus of a comet. The amount of heating is thought to decrease with distance, and was more than what could be explained by simple incoming solar radiation.

“Interestingly, we found that the temperature measured for water gas in the coma did not decrease significantly with the distance from the nucleus, which implies a heating mechanism,” says Erika Gibb (University of Missouri—St Louis) in the recent press release.

One possibility is ionization via sunlight close to the nucleus. “Another possibility is there may be solid chunks of ice flying

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More Than Half of Near Earth Objects Could Be “Dark Comets”

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Next time you’re visiting the seaside or a large lake, or even sipping a frosty glass of water, think about where it all originated. There are many pathways that water could have taken to the infant Earth: via comets, “wet asteroids”, and outgassing from early volcanism. Aster Taylor, a University of Michigan graduate student has another idea: dark comets. They’re something of a cross between asteroids and comets and could have played a role in water delivery to our planet.

Dark comets are small Solar System bodies. They have short rotational periods thanks to non-gravitational pushes by sublimation that creates jets. These mysterious objects probably make up more than half of all near-Earth objects.

Dark Comets and Asteroids

Planetary scientists consider dark comets as a population of active asteroids. Yet, they aren’t in the same category as regular asteroids and comets. They’re on near-Earth orbits, so when one passes close to the Sun, it doesn’t grow a coma. That lack of a coma is why they’re called “dark comets.” Yet, their sublimation jets appear to be a response to radiation from the Sun. They’re likely rich in water ice so that raises an interesting question. Could these also have been a source of water for Earth in the distant past?

“We don’t know if these dark comets delivered water to Earth,” said Taylor. “But we can say that there is still debate over how exactly the Earth’s water got here,” Taylor said. “The work we’ve done has shown that this is another pathway to get ice from somewhere in the rest of the Solar System to the Earth’s environment.”

Water Delivery From Small Bodies

The story of how Earth got its water is still unfolding. One theory says infant Earth formed with molecular precursors to water. Another one says that water-laden asteroids and comets brought water to Earth during or just after formation. That’s interesting because most asteroids exist near the so-called “ice line”—a region well beyond Earth where liquids freeze. Something propelled them to the inner solar system. When they got close to the Sun, their ice sublimated. That’s actually what happens with a comet, too. So, maybe both comets and planetesimals were water-bearers during Earth’s formation. Volcanic activity could have released their trapped water as vapor.

An artist's rendering of the early Moon and Earth, which sustained many asteroid impacts. Many of those asteroids and possibly dark comets contributed their water to the infant Earth. As it cooled, the water outgassed as vapor. Credit: Simone Marchi (SwRI)/SSERVI/NASA
An artist’s rendering of the early Moon and Earth, which sustained many asteroid impacts. Many of those asteroids and possibly dark comets contributed their water to the infant Earth. As it cooled, the water outgassed as vapor. Credit: Simone Marchi (SwRI)/SSERVI/NASA

How about the wet asteroids, though? Where did they come from? We know that comets formed out in the cooler reaches of the protosolar nebula. Somehow they make their way (through gravitational perturbations and dynamical action) to the inner solar system. There, they have collided with Earth (just like Comet Shoemaker-Levy 9 encountered Jupiter in 1994).

That leaves the water ice-rich asteroids or “dark comets”. Most water-rich asteroids or “dark comets” exist in the Asteroid Belt. However, plenty of them orbit in the inner solar system, too. Those near-Earth objects probably made their way sunward due to gravitational interactions with Jupiter or other worlds. Those with some amount of water ice trapped on or below their surfaces could have been a delivery mechanism for water to early Earth.

An artist's concept of a rocky planet and a rain of comets and other objects pummeling its surface. These, along with dark comets, could have delivered water to early Earth. Courtesy NASA/JPL.Did you miss our previous article…
https://mansbrand.com/the-first-5-things-i-do-in-camp-when-backpacking-3/

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The First 5 Things I Do in Camp When Backpacking

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By Michael Lanza

I doubt that I had any typical routine when arriving at a campsite on my earliest backpacking trips; like many backpackers, I probably just dropped my pack, shucked off my boots, and kicked back until motivated to move by the urge to eat, drink, get warm, or go to the bathroom. Over the years, though, I’ve developed a routine that I follow almost religiously when I arrive in camp at the end of a day of backpacking. These five simple, quick, almost effortless steps make a world of difference in how good I feel that evening and the next morning, and how well I sleep.

These tips derive from habits I’ve gradually adopted over more than three decades and innumerable backpacking trips across the U.S. and around the world, including the 10 years I spent as Northwest Editor of Backpacker magazine and even longer running this blog. These are practices I’ve followed in every type of environment and on every type of trip, from easier outings with my family when our kids were young—although it didn’t always feel “easier” carrying much of our children’s gear and food—to extreme adventures backpacking 20 to 30 or more miles per day.

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Hi, I’m Michael Lanza, creator of The Big Outside. Click here to sign up for my FREE email newsletter. Join The Big Outside to get full access to all of my blog’s stories. Click here for my e-books to classic backpacking trips. Click here to learn how I can help you plan your next trip.

A backpacker hiking the Doubletop Mountain Trail, Wind River Range WY.
” data-image-caption=”My wife, Penny, backpacking the Doubletop Mountain Trail in the Wind River Range, Wyoming. Click photo to see “The 10 Best Backpacking Trips in the Wind River Range.”
” data-medium-file=”https://i0.wp.com/tbo-media.sfo2.digitaloceanspaces.com/wp-content/uploads/2023/05/06224931/Wind8-014-Penny-Beach-backpacking-the-Doubletop-Mountain-Trail-Wind-River-Range-WY..jpg?fit=300%2C200&ssl=1″ data-large-file=”https://i0.wp.com/tbo-media.sfo2.digitaloceanspaces.com/wp-content/uploads/2023/05/06224931/Wind8-014-Penny-Beach-backpacking-the-Doubletop-Mountain-Trail-Wind-River-Range-WY..jpg?fit=900%2C600&ssl=1″ tabindex=”0″ role=”button” src=”https://i0.wp.com/tbo-media.sfo2.digitaloceanspaces.com/wp-content/uploads/2023/05/06224931/Wind8-014-Penny-Beach-backpacking-the-Doubletop-Mountain-Trail-Wind-River-Range-WY.-1024×683.jpg?resize=900%2C600&ssl=1″ alt=”A backpacker hiking the Doubletop Mountain Trail, Wind River Range WY.” class=”wp-image-58503″ srcset=”https://tbo-media.sfo2.digitaloceanspaces.com/wp-content/uploads/2023/05/06224931/Wind8-014-Penny-Beach-backpacking-the-Doubletop-Mountain-Trail-Wind-River-Range-WY..jpg 1024w, https://tbo-media.sfo2.digitaloceanspaces.com/wp-content/uploads/2023/05/06224931/Wind8-014-Penny-Beach-backpacking-the-Doubletop-Mountain-Trail-Wind-River-Range-WY..jpg 300w, https://tbo-media.sfo2.digitaloceanspaces.com/wp-content/uploads/2023/05/06224931/Wind8-014-Penny-Beach-backpacking-the-Doubletop-Mountain-Trail-Wind-River-Range-WY..jpg 768w, https://tbo-media.sfo2.digitaloceanspaces.com/wp-content/uploads/2023/05/06224931/Wind8-014-Penny-Beach-backpacking-the-Doubletop-Mountain-Trail-Wind-River-Range-WY..jpg 150w, https://tbo-media.sfo2.digitaloceanspaces.com/wp-content/uploads/2023/05/06224931/Wind8-014-Penny-Beach-backpacking-the-Doubletop-Mountain-Trail-Wind-River-Range-WY..jpg 1200w” sizes=”(max-width: 900px) 100vw, 900px” data-recalc-dims=”1″ />My wife, Penny, backpacking the Doubletop Mountain Trail in the Wind River Range, Wyoming. Click photo to see “The 10 Best Backpacking Trips in the Wind River Range.”

Follow these tips and I think you’ll make your campsite hours—and backpacking trips as a whole—more comfortable.

Click on any photo to read more about that place and
Did you miss our previous article…
https://mansbrand.com/neutron-star-is-spraying-jets-like-a-garden-sprinkler/

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Neutron Star is Spraying Jets Like a Garden Sprinkler

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X-ray binaries are some of the oddest ducks in the cosmic zoo and they attract attention across thousands of light-years. Now, astronomers have captured new high-resolution radio images of the first one ever discovered. It’s called Circinus X-1. Their views show a weird kind of jet emanating from the neutron star member of the binary. The jet rotates like an off-axis sprinkler as it spews material out through surrounding space, sending shockwaves through the interstellar medium.

The MeerKAT radio telescope in South African spotted the S-shaped jets emanating from the neutron star. Its images are the first-ever high-resolution views of such jets, according to lead researcher Fraser Cowie. “This image is the first time we have seen strong evidence for a precessing jet from a confirmed neutron star,” he said, referring to the neutron star’s off-axis spin. “This evidence comes from both the symmetric S shape of the radio-emitting plasma in the jets and from the fast, wide shockwave, which can only be produced by a jet changing direction.”

Such an awkward spin gives the jets their peculiar S-like configuration. Since scientists aren’t completely sure what phenomena caused them to launch in the first place, studying the odd behavior gives insight into the extreme physics behind its existence.

Examining the Neutron Star Jets in Detail

The MeerKAT measurements showed not only the jet but revealed termination shocks moving away from the neutron star. These occur in regions where the jets slam into material in surrounding space. This is the first time astronomers found such shocks around an X-ray binary like Circinus X-1. Those waves are moving fast—at about 10 percent the speed of light and their structure points back to the jet as their source. “The fact that these shockwaves span a wide angle agrees with our model,” Cowie said. “So we have two strong pieces of evidence telling us the neutron star jet is processing.”

A MeerKAT radio image of the S-shape jet precessing in the Circinus X-1 X-ray binary pair system. The jet emanates as a result of the accretion of material around the neutron star. Courtesy: Fraser Cowie, Attribution CC BY 4.0.
A MeerKAT radio image of the S-shape jet precessing in the Circinus X-1 X-ray binary pair system. The jet emanates as a result of the accretion of material around the neutron star. Courtesy: Fraser Cowie, Attribution CC BY 4.0.

The speed of those shockwaves turns them into particle accelerators producing high-energy cosmic rays. The fact that those rays exist tells astronomers the action around the X-ray binary is extremely energetic. That high-energy activity has grabbed astronomers’ attention for half a century. Still, it remains a mysterious system, so as Cowie points out, it’s important to observe the jets and see how their behavior changes over time. “Several aspects of its behavior are not well explained so it’s very rewarding to help shed new light on this system, building on 50 years of work from others,” he said. “The next steps will be to continue to monitor the jets and see if they change over time in the way we expect. This will allow us to more precisely measure their properties and continue to learn more about this puzzling object.”

bout Circinus X-1

The Circinus X-1 system contains a neutron star and a companion. The pair lies some 30,000 light-years away in the direction of the southern hemisphere constellation Circinus. It was first spotted in June 1969 by an Aerobee suborbital rocket carrying X-ray-sensitive instruments and has been studied for years by astronomers using optical, X-ray, and radio telescopes.

Composite image of Circinus X-1, which is about 24,000 light-years from Earth in the constellation Circinus. Credit: X-ray: NASA/CXC/Univ. of Wisconsin-Madison/S. Heinz et al; Optical: DSS; Radio: Did you miss our previous article…
https://mansbrand.com/experimental-radar-technique-reveals-the-composition-of-titans-seas/

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