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For years, people noticed strange features on the Moon dubbed “Lunar Swirls.” They’re bright regions that appear to be concentrations of lighter-colored material on the surface. It turns out that interactions between the solar wind and magnetic regions on the Moon may play a role at two sites.

Scientists long thought that these swirls weren’t related to the surrounding topography, but it turns out there’s some kind of interaction going on between the swirl deposition and the surface. Planetary Science Institute senior scientist John Weirich led a team to study topographic data for lunar swirls at high resolution. They found a correlation between the swirl areas and lower topography in a region called the Reiner Gamma swirl.

bout Swirl Regions

The Moon has a number of similar regions with high-contrast bright markings that appear to loop across the surface. Generally, they look like wide bright swirls separated by darker off-swirl lanes. The fact that they exist spurs questions about how they form and there isn’t a clear answer, yet. Once that mystery is solved, scientists will have a better understanding of how the lunar surface is affected by the solar wind, bombardment by micrometeorites, how the lunar soil “migrates”, and what other effects the local environment has on the surface.

Lunar swirls are found in several regions on the Moon. Courtesy NASA.
Lunar swirls are found in several regions on the Moon. Courtesy NASA.

“Lunar swirls have piqued scientists’ interest since they were discovered, partly because the scientific community doesn’t completely understand how they formed. There are many hypotheses about their formation process. Each hypothesis has observations that support it, but there are also other observations that contradict them,” Weirich said. “Since we don’t have a full understanding of how these swirls formed, we don’t completely understand the story they can tell us about the Moon. Forming them could involve a combination of well-understood processes interacting together or a currently unknown process. Unusual objects or phenomena are sometimes the key to obtaining deeper knowledge, and for this reason, lunar swirls are very intriguing. And the fact that they look really cool.”

Studying Swirls in Higher Detail

To do their work, Weirich’s team looked at earlier research showing that bright areas are 2-3 meters lower than dark areas, particularly in the Mare Ingenii lunar swirl. “However, it is not as simple as the bright areas are uniformly lower than the dark areas. If that was the case this relationship between topography and swirl would be easy to demonstrate by comparing an elevation map to a picture of the swirl. Instead, this relationship is only seen when we compare the average height of the bright areas and the average height of the dark areas.”

Weirich studied Lunar Reconnaissance Orbiter mission images and applied a special software suite to determine the surface topography. The team also used machine-learning tools on specific images. It classified the swirls into various units: bright areas (on-swirl)and dark areas (or “off-swirl”). The studies allowed them to identify transition regions between the two units, and they labeled those “diffuse-swirl”.

The correlation between topography and swirl formation still doesn’t explain exactly why they form. But, it does give planetary scientists some new clues as they study other swirl features on the Moon. At present, there are several theories about formation, but none of them explain all of the details. One idea is that they formed as a result of cometary impacts. That explains the brightness of these features. Another theory is that the swirls form when weak magnetic fields protect lighter-colored lunar surface soil (regolith) from the solar wind. Finally, weak electric fields created by brief interactions between the magnetic anomalies and solar wind plasma could play a role. Those fields could affect electrically charged fine dust on the surface. How topography plays into any of these theories is still an unknown.

How They Did It

The specialized software the team used does stereophotoclinometry to analyze the topography of a surface. It combines stereo imaging and photoclinometry

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Backpacking the Teton Crest Trail—A Photo Gallery

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By Michael Lanza

As we hiked up the North Fork of Cascade Canyon on the Teton Crest Trail in Grand Teton National Park, moments after the path emerged from the forest into a meadow strewn with boulders and still dappled with blooming wildflowers in late August, my friend David turned to look over his shoulder and blurted out, “Oh, wow, look at that view!” Behind us, the sheer north faces of the Grand Teton and Mount Owen towered a vertical mile above us, shooting straight up over the canyon like fireworks (photo above).

By that point on our trip, though, uncontrolled outbursts of awe were occurring several times a day. That’s what it’s like to backpack the Teton Crest Trail.

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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 on the Teton Crest Trail in Grand Teton National Park.
” data-image-caption=”Jeff Wilhelm backpacking the Teton Crest Trail in Grand Teton National Park. Click photo for my e-book “The Complete Guide to Backpacking the Teton Crest Trail.”
” data-medium-file=”https://i0.wp.com/tbo-media.sfo2.digitaloceanspaces.com/wp-content/uploads/2019/09/06232037/DSC_2401.jpg?fit=300%2C200&ssl=1″ data-large-file=”https://i0.wp.com/tbo-media.sfo2.digitaloceanspaces.com/wp-content/uploads/2019/09/06232037/DSC_2401.jpg?fit=900%2C599&ssl=1″ src=”https://i0.wp.com/tbo-media.sfo2.digitaloceanspaces.com/wp-content/uploads/2019/09/06232037/DSC_2401-1024×681.jpg?resize=900%2C599&ssl=1″ alt=”A backpacker on the Teton Crest Trail in Grand Teton National Park.” class=”wp-image-35224″ srcset=”https://tbo-media.sfo2.digitaloceanspaces.com/wp-content/uploads/2019/09/06232037/DSC_2401.jpg 1024w, https://tbo-media.sfo2.digitaloceanspaces.com/wp-content/uploads/2019/09/06232037/DSC_2401.jpg 300w, https://tbo-media.sfo2.digitaloceanspaces.com/wp-content/uploads/2019/09/06232037/DSC_2401.jpg 768w, https://tbo-media.sfo2.digitaloceanspaces.com/wp-content/uploads/2019/09/06232037/DSC_2401.jpg 1080w, https://tbo-media.sfo2.digitaloceanspaces.com/wp-content/uploads/2019/09/06232037/DSC_2401.jpg 1200w” sizes=”(max-width: 900px) 100vw, 900px” data-recalc-dims=”1″ />Jeff Wilhelm backpacking the Teton Crest Trail in Grand Teton National Park. Click photo for my e-book “The Complete Guide to Backpacking the Teton Crest Trail.”

Three friends and I backpacked a 36-mile traverse of Grand Teton National Park, mostly on the Teton Crest Trail, in late August—in many ways, an ideal time to hike there. While I’ve backpacked the TCT several times now, it was the first time for all three of them.

Seeing the reactions of these friends—every one of them very experienced backpackers who’ve taken numerous trips with me—to the scenery along this classic trek, reaffirmed my opinion that few multi-day hikes offer so much grandeur almost every step of way like the Teton Crest Trail. But I’ll let the photos in this story make that case.

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A backpacker on the Teton Crest Trail in Grand Teton National Park.
” data-image-caption=”David Gordon backpacking the Teton Crest Trail in Grand Teton National Park. Click photo to get my customized help planning your trip.
” data-medium-file=”https://i0.wp.com/tbo-media.sfo2.digitaloceanspaces.com/wp-content/uploads/2019/09/06232029/DSC_2658.jpg?fit=300%2C175&ssl=1″ data-large-file=”https://i0.wp.com/tbo-media.sfo2.digitaloceanspaces.com/wp-content/uploads/2019/09/06232029/DSC_2658.jpg?fit=900%2C525&ssl=1″ src=”https://i0.wp.com/tbo-media.sfo2.digitaloceanspaces
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New Simulation Explains how Supermassive Black Holes Grew so Quickly

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One of the main scientific objectives of next-generation observatories (like the James Webb Space Telescope) has been to observe the first galaxies in the Universe – those that existed at Cosmic Dawn. This period is when the first stars, galaxies, and black holes in our Universe formed, roughly 50 million to 1 billion years after the Big Bang. By examining how these galaxies formed and evolved during the earliest cosmological periods, astronomers will have a complete picture of how the Universe has changed with time.

As addressed in previous articles, the results of Webb‘s most distant observations have turned up a few surprises. In addition to revealing that galaxies formed rapidly in the early Universe, astronomers also noticed these galaxies had particularly massive supermassive black holes (SMBH) at their centers. This was particularly confounding since, according to conventional models, these galaxies and black holes didn’t have enough time to form. In a recent study, a team led by Penn State astronomers has developed a model that could explain how SMBHs grew so quickly in the early Universe.

The research team was led by W. Niel Brandt, the Eberly Family Chair Professor of Astronomy and Astrophysics at Penn State’s Eberly College of Science. Their research is described in two papers presented at the 244th meeting of the American Astronomical Society (AAS224), which took place from June 9th to June 13th in Madison, Wisconsin. Their first paper, “Mapping the Growth of Supermassive Black Holes as a Function of Galaxy Stellar Mass and Redshift,” appeared on March 29th in The Astrophysical Journal, while the second is pending publication. Fan Zou, an Eberly College graduate student, was the lead author of both papers.

Illustration of an active quasar. What role does its dark matter halo play in activating the quasar? Credit: ESO/M. Kornmesser
Illustration of an active quasar. New research shows that SMBHs eat rapidly enough to trigger them. Credit: ESO/M. Kornmesser

As they note in their papers, SMBHs grow through two main channels: by accreting cold gas from their host galaxy or merging with the SMBHs of other galaxies. When it comes to accretion, previous research has shown that a black hole’s accretion rate (BHAR) is strongly linked to its galaxy’s stellar mass and the redshift of its general stellar population. “Supermassive black holes in galaxy centers have millions-to-billions of times the mass of the Sun,” explained Zhou in a recent NASA press release. How do they become such monsters? This is a question that astronomers have been studying for decades, but it has been difficult to track all the ways black holes can grow reliably.”

For their research, the team relied on forefront X-ray sky survey data obtained by NASA’s Chandra X-ray Observatory, the ESA’s X-ray Multi-Mirror Mission-Newton (XMM-Newton), and the Max Planck Institute for Extraterrestrial Physics’ eROSITA telescope. They measured the accretion-driven growth in a sample of 8000 active galactic nuclei (AGNs) located in 1.3 million galaxies. This was combined with IllustrisTNG, a suite of state-of-the-art cosmological simulations that model galaxy formation, evolution, and mergers from Cosmic Dawn to the present. This combined approach has provided the best modeling to date of SMBH growth over the past 12 billion years. Said Brandt:

“During the process of consuming gas from their hosting galaxies, black holes radiate strong X-rays, and this is the key to tracking their growth by accretion. We measured the accretion-driven growth using X-ray sky survey data accumulated over more than 20 years from three of the most powerful X-ray facilities ever launched into space.

“In our hybrid approach, we combine the observed growth by accretion with the simulated growth through mergers to reproduce the growth history of supermassive black holes. With this new approach, we believe we have produced the most realistic picture of the growth of supermassive black holes up to the present day.”

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This still image shows the timeline running from the Big
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10 Tips for Taking Kids on Their First Backpacking Trip

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By Michael Lanza

Whether you’re a family of novices planning your first backpacking trip or an experienced backpacker ready to take your kids on their first multi-day hike, heed this friendly advice: You’re in for some surprises. And I speak from experience. I’d been backpacking for years—in fact, I was already working as a professional backpacker—when my wife (also a longtime backpacker) and I first dove into the grand new adventure of taking our young kids into the wilderness.

We learned a lot. But the biggest lesson was this: Our backcountry adventures brought us closer together as a family and helped mold our children into eager and skilled backpackers and confident young adults with a passion and appreciation for the outdoors—and who seize every chance to spend time with us (their parents!) outdoors (and indoors!).

This article shares lessons I learned while taking our kids on countless backpacking trips since they were quite little and over the course of the 10 years I spent as Northwest Editor of Backpacker magazine and even longer running this blog.

Tet19 047 Me on Teton Crest Trail copy cropped 33
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 young girl backpacking the High Sierra Trail above Hamilton Lakes, Sequoia National Park.
” data-image-caption=”My daughter, Alex, backpacking the High Sierra Trail above Hamilton Lakes, Sequoia National Park, which is also the lead photo at the top of this story.
” data-medium-file=”https://i0.wp.com/tbo-media.sfo2.digitaloceanspaces.com/wp-content/uploads/2020/05/06230302/Sierra3-040-High-Sierra-Trail-above-Hamilton-Lakes-Sequoia-N.P.-CA-2.jpg?fit=300%2C199&ssl=1″ data-large-file=”https://i0.wp.com/tbo-media.sfo2.digitaloceanspaces.com/wp-content/uploads/2020/05/06230302/Sierra3-040-High-Sierra-Trail-above-Hamilton-Lakes-Sequoia-N.P.-CA-2.jpg?fit=900%2C598&ssl=1″ src=”https://i0.wp.com/tbo-media.sfo2.digitaloceanspaces.com/wp-content/uploads/2020/05/06230302/Sierra3-040-High-Sierra-Trail-above-Hamilton-Lakes-Sequoia-N.P.-CA-2-1024×680.jpg?resize=900%2C598&ssl=1″ alt=”A young girl backpacking the High Sierra Trail above Hamilton Lakes, Sequoia National Park.” class=”wp-image-45459″ srcset=”https://tbo-media.sfo2.digitaloceanspaces.com/wp-content/uploads/2020/05/06230302/Sierra3-040-High-Sierra-Trail-above-Hamilton-Lakes-Sequoia-N.P.-CA-2.jpg 1024w, https://tbo-media.sfo2.digitaloceanspaces.com/wp-content/uploads/2020/05/06230302/Sierra3-040-High-Sierra-Trail-above-Hamilton-Lakes-Sequoia-N.P.-CA-2.jpg 300w, https://tbo-media.sfo2.digitaloceanspaces.com/wp-content/uploads/2020/05/06230302/Sierra3-040-High-Sierra-Trail-above-Hamilton-Lakes-Sequoia-N.P.-CA-2.jpg 768w, https://tbo-media.sfo2.digitaloceanspaces.com/wp-content/uploads/2020/05/06230302/Sierra3-040-High-Sierra-Trail-above-Hamilton-Lakes-Sequoia-N.P.-CA-2.jpg 150w, https://tbo-media.sfo2.digitaloceanspaces.com/wp-content/uploads/2020/05/06230302/Sierra3-040-High-Sierra-Trail-above-Hamilton-Lakes-Sequoia-N.P.-CA-2.jpg 1200w” sizes=”(max-width: 900px) 100vw, 900px” data-recalc-dims=”1″ />My daughter, Alex, backpacking the High Sierra Trail above Hamilton Lakes, Sequoia National Park.

Follow the tips below to make your family backpacking trips a success and ensure that your kids want to go again and again. Like many stories at The Big Outside, much of this one is free for anyone to read but reading the entire story requires a paid subscription. If you’re already a subscriber, thank you for supporting my blog.

Please share your thoughts, questions, or your own tips in the comments section at the bottom of this story. I try to
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