Six days after Earth entered a stream of high-speed solar wind ... we're still inside. The solar wind continues to blow faster than 500 km/s on Oct. 31st. Although it is not as gusty as it was during first contact on Oct. 25th, the relentless pressure of the sun's electrically charged wind on Earth's magnetic field is causing the poles to glow with beautiful auroras. Marketa S. Murray sends this picture from Fairbanks, Alaska, on Oct. 29th:

"When you stand there and the whole sky is just dancing overhead, your adrenaline and endorphin get so high," says Murray. "It's mind blowing every time it happens. It never gets old, even for an Alaskan!"

Until Earth fully exits this stream, polar auroras remain likely. A good way to follow the action is to tune into a live webcam in Sweden's Abisko National Park. "We have seen the lights nearly every night in October!" says Chad Blakley of Lights over Lapland, who operates the camera.
Watch it now.    www.spaceweather.com

During this week's solar wind event, observers around the Arctic Circle reported auroras of an unusual color. "Crazy pink," says Frank Meissner, who photographed the phenomenon on Oct. 26th from Tromsø, Norway:

"It was awesome," he says. "Flash-like bursts were zooming all over the sky."

Watching from Tromsø on the same night, veteran observer Terence Murtagh says "even with many hundreds of aurora sightings under my belt, I've never witnessed such distinct pink colors clearly visible and bright to the naked eye. They were almost too bright to photograph properly."

The pink color is probably a sign of nitrogen. Most auroras are green--a verdant glow caused by energetic particles from space hitting oxygen atoms 100 km to 300 km above Earth's surface. Seldom-seen pink appears when the energetic particles descend lower than usual, striking nitrogen molecules at the 100 km level and below. More examples may be found in the realtime photo gallery: Realtime Aurora Photo Gallery
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Not all space weather occurs high overhead. Sometimes it happens in the soil beneath our feet. Example: On Oct. 23rd in the Lofoten Islands of Norway, electrical currents began to flow through the ground, back and forth with a sinusoidal period of 74 seconds. Rob Stammes recorded the phenomenon at his geomagnetic observatory:

"Just after midnight UTC and around 02.36 local time, my ground current instruments picked up these very stable pulsations," says Stammes.

What's happening here? Ground currents are a sign of changing magnetic fields. Earth's magnetic field around the Lofoten Islands was swinging back and forth, inducing a sinusoidal amperage in the soil beneath Stamme's observatory.

These are natural ultra-low frequency oscillations known to researchers as "pulsations continuous" (Pc). The physics is familiar to anyone who has studied bells or resonant cavities. Earth's magnetic field extends out into space and carves out a cavity in the surrounding solar wind. Pressure fluctuations in the solar wind can excite wave modes in the cavity--usually in a noisy cacophany of many frequencies, but sometimes with almost-monochromatic purity. In such cases, Earth's magnetic field "rings like a bell" with slow tones that reach all the way down to the ground. That's what happened on Oct. 23rd. References: #1, #2, #3.
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A strong G3-class geomagnetic storm is underway on Oct. 25th as Earth enters a stream of solar wind flowing from a coronal hole on the sun. First contact with the stream produced a magnificent outburst of auroras over Alaska. Marketa S. Murray sends this picture from Fairbanks AK:

"The storm finally hit," says Murray, "and the auroras were unbelievable."
More auroras are in the offing tonight as the solar wind is blowing faster than ~700 km/s. Around the Arctic Circle, the Northern Lights should be quite bright. Lesser displays could cross the Canadian border into the United States.
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Rosie Vare : AOL Travel UK : 20 Oct 2016

This unusual shaped cloud has been spotted in the sky over South Carolina.

Cory Hearn captured on camera the rare weather phenomenon, which appears in the shape of an angel with its wings spread wide.  Speaking on the footage, Cory says: "Check that out. Is that not an angel or what?  Nobody would believe me if I didn't do this live, but I want you to look at this cloud in the sky.  I don't know that I've ever seen with my own two eyes this type of cloud. Isn't it amazing?  I'm seeing an angel, I don't know if anybody sees anything different."

He later told People that it was the most amazing thing he'd ever seen in his life. "This couldn't have come at a better time and other people seem to agree."

Published on Oct 19, 2016
It’s not often an angel is spotted in the sky, but a curious onlooker managed to capture what turned out to be a cloud shape of a guardian on Facebook Live. Cory Hearon filmed the cloud in Camden, South Carolina, and the live stream has now been viewed more than 7 million times.

SC Man's Video of 'Angel'-Like Cloud Goes Viral

South Carolina Man Captures ‘Angel’ Cloud on Video: ‘It’s a Sign Everything Is Going to Be Okay’
 
Last week, the Camden, South Carolina, father of three was in his car when he looked to his left and saw an angel-like cloud formation that left him awestruck.  “It was the most amazing thing I’ve ever seen in my life,” Hearon, 37, tells PEOPLE.  “I was in shock for the first two minutes, and I thought I better get a video of this so there won’t be any question or doubt about what I saw,” he says.

Hearon, who says he watched the cloud for 45 minutes before it started to dissipate, posted a Facebook Live video that has received millions of views.  “Look at this cloud in the sky. Is that not an angel or what?” he says in the video. “This is blowing my mind.”

There's a full Moon this weekend. That means it's time to be alert for moonbows. Ian Glendinning spotted this one arcing over a lightning bolt in Northumberland UK:

"The moonbow framed the lightning nicely--a rare and beautiful coincidence," says Glendinning.
Everyone knows what lightning is. But a moonbow? It's the same as a rainbow with the Moon playing the role of Sun. Raindrops falling in the Northumberland night caught the rays of the waxing full Moon and spread them into a fan of prismatic color.

Glendinning's exposure revealed something even more rare: a secondary moonbow. It's the faint 'bow arciing above the brighter primary. Primary rainbows are caused by single reflections inside raindrops; secondary bows are caused by double reflections. Watch for them both this weekend.
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Powerful Hurricane Matthew is scouring the islands of the Caribbean with 120 mph winds.  Orbiting high above the tempest in the darkness of space, the NOAA/NASA Suomi NPP satellite has observed the storm's ripple effect on the upper atmosphere:

These ripples are called "gravity waves"--essentially, waves of pressure and temperature excited by the upward motion of air from the storm below. Gravity does not vary inside these waves; instead, they get their name from the fact that gravity acts as a vertical restoring force that tries to restore equilibrium to up-and-down moving air. Similar patterns have been observed above powerful thunderstorms. 

Matthew's gravity waves are visible from the ground as well.  Frankie Lucena of Cabo Rojo, Puerto Rico, captured them in his recent snapshots of sprites above the hurricane:

"Steven Miller of Colorado State University was kind enough to prepare these images for me to confirm that my sprite photo did contain gravity waves," says Lucena. "My location in southwestern Puerto Rico is noted in the satellite image above. By pointing my camera at the lightning, I also caught the waves."

Left to themselves, gravity waves would be invisible to the human eye. We see them, however, because they impress their patterns upon a luminous phenomenon called "airglow." Learn more about that in the next article, Amazing Airglow over Easter Island.
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If you shatter a bone in the future, a 3D printer and some special ink could be your best medicine. Researchers have created what they call "hyperelastic bone" that can be manufactured on demand and works almost as well as the real thing, at least in monkeys and rats. Though not ready to be implanted in humans, bioengineers are optimistic that the material could be a much-needed leap forward in quickly mending injuries ranging from bones wracked by cancer to broken skulls.

"This is a neat way to overcome the challenges we face in generating bone replacements," says Jos Malda, a biomaterials engineer from Utrecht University in the Netherlands who was not involved in the work. "The scaffold is simpler to make than others and it offers more benefits."

Surgeons currently replace shattered or missing bones with a number of things. The most common option is an autograft, where a piece of bone is taken from a patient's own body, usually from a hip or a rib, and implanted where it's needed elsewhere in that same patient's skeleton. Surgeons prefer autografts because they're real bone complete with stem cells that give rise to cartilage and bone cells to provide extra support for the new graft. (Humans can't regrow entire skeletons from scratch with stem cells, but existing bone can signal stem cells where to grow and what to grow into.) What's more, because the new bone replacement comes from a patient's own body, there's no risk of immune rejection. But only so much of a person's skeleton is available for grafting, and doing so tacks on another painful surgery and recovery for the patient.

Another bone replacement option is creating a scaffold for bone to grow on. These scaffolds, made of both natural and synthetic materials, work like the framing of a building. When inserted into the body, stem cells latch onto the structure and differentiate into cells that start to build bone, much as construction workers assemble walls, floors, and glass around a skyscraper's steel girders.

Or, at least, that's how it should work—unlike in an autograft, stem cells don't always turn into the needed bone or cartilage because of the scaffolds' material makeup. Researchers have gotten stem cells to grow on a ceramic material called calcium phosphate (CaP), but this scaffold is stiff and brittle, making it difficult to implant into patients. To make matters worse, the immune system occasionally sees these scaffolds as foreign and attacks them, preventing any bone growth at all. And if a scaffold is to be used to regenerate small bones, such as many of those found in the face, for example, doctors worry that it would take too much time and money to make them from CaP.

Researchers at Northwestern University, Evanston, in Illinois are working on a material to remedy all of these issues. Their hyperelastic bone is a type of scaffold made up of hydroxyapatite, a naturally occurring mineral that exists in our bones and teeth, and a biocompatible polymer called polycaprolactone, and a solvent. Hydroxyapatite provides strength and offers chemical cues to stem cells to create bone. The polycaprolactone polymer adds flexibility, and the solvent sticks the 3D-printed layers together as it evaporates during printing. The mixture is blended into an ink that is dispensed by the printer, layer by layer, into exact shapes matching the bone that needs to be replaced. The idea is, a patient would come in with a nasty broken bone—say, a shattered jaw—and instead of going through painful autograft surgeries or waiting for a custom scaffold to be manufactured, he or she could be x-rayed and a 3D-printed hyperelastic bone scaffold could be printed that same day.

"We're printing flexible scaffolds that will encourage bone to grow through and around them," says Ramille Shah, a material science engineer and co-author on the study.

This article in its entirety can be read here.

Sept. 20, 2016: Readers, thank you for your patience while we continue to develop this new section of Spaceweather.com. We've been working to streamline our data reduction, allowing us to post results from balloon flights much more rapidly, and we have developed a new data product, shown here:

This plot displays radiation measurements not only in the stratosphere, but also at aviation altitudes. Dose rates are expessed as multiples of sea level. For instance, we see that boarding a plane that flies at 25,000 feet exposes passengers to dose rates ~10x higher than sea level. At 40,000 feet, the multiplier is closer to 50x. These measurements are made by our usual cosmic ray payload as it passes through aviation altitudes en route to the stratosphere over California.

What is this all about? Approximately once a week, Spaceweather.com and the students of Earth to Sky Calculus fly space weather balloons to the stratosphere over California. These balloons are equipped with radiation sensors that detect cosmic rays, a surprisingly "down to Earth" form of space weather. Cosmic rays can seed clouds, trigger lightning, and penetrate commercial airplanes. Furthermore, there are studies ( #1, #2, #3, #4) linking cosmic rays with cardiac arrhythmias and sudden cardiac death in the general population. Our latest measurements show that cosmic rays are intensifying, with an increase of more than 12% since 2015:

Why are cosmic rays intensifying? The main reason is the sun. Solar storm clouds such as coronal mass ejections (CMEs) sweep aside cosmic rays when they pass by Earth. During Solar Maximum, CMEs are abundant and cosmic rays are held at bay. Now, however, the solar cycle is swinging toward Solar Minimum, allowing cosmic rays to return. Another reason could be the weakening of Earth's magnetic field, which helps protect us from deep-space radiation.

The radiation sensors onboard our helium balloons detect X-rays and gamma-rays in the energy range 10 keV to 20 MeV. These energies span the range of medical X-ray machines and airport security scanners.

The data points in the graph above correspond to the peak of the Reneger-Pfotzer maximum, which lies about 67,000 feet above central California. When cosmic rays crash into Earth's atmosphere, they produce a spray of secondary particles that is most intense at the entrance to the stratosphere. Physicists Eric Reneger and Georg Pfotzer discovered the maximum using balloons in the 1930s and it is what we are measuring today.
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Researchers have long known that one of the van Allen Radiation Belts dips down toward Earth over South America, creating a zone of high radiation called "The South Atlantic Anomaly" (SAA). Since its discovery in 1958, the SAA has been shape-shifting, growing larger and intensifying.  A map published just last week in the American Geophysical Union's journal Space Weather Quarterly outlines the anomaly with new precision:

When a spacecraft in low-Earth orbit passes through the anomaly, "the radiation causes faults in spacecraft electronics and can induce false instrument readings," explains Bob Schaefer of the Johns Hopkins University Applied Physics Lab, lead author of the paper reporting the results. "We actually used these spurious signals to map out the radiation environment at an altitude of 850 km."

Specifically, they looked at pulses of noise in an ultraviolet photometer carried aboard many polar orbiting Defense Meteorological Satellite Program (DMSP) satellites. When high-energy protons in the SAA pass through these sensors, they  produce spurious signals--or, in the case of this study, valuable data. By monitoring the rate of spurious UV pulses, the researchers were able to trace the outlines of the anomaly and monitor its evolution over a period of years.

They found that the anomaly is slowly drifting north and west at rates of 0.16 deg/yr and 0.36 deg/yr, respectively. Currently, it is most intense over a broad region centered on Sao Paulo, Brazil, including much of Paraguay, Uruguay, and northern Argentina. They also detected a seasonal variation: On average, the SAA is most intense in February and again in September-October. In this plot, yearly average counts have been subtracted to reveal the double-peaked pattern:

One maximum coincides with an equinox, but the other does not. The authors were not able to explain the origin of this unexpected pattern. 

The solar cycle matters, too, as the data revealed a yin-yang anti-correlation with sunspots. "During years of high solar activity, the radiation intensity is lower, while during solar quiet years the radiation intensity is higher," writes Schaefer.

According to orthodox thinking, the SAA reaches down from space to within about 200 km of Earth's surface. Below that altitude, its effects should be mitigated by the shielding of Earth's atmosphere and geomagnetic field. To test this idea, Spaceweather.com and Earth to Sky Calculus have undertaken a program to map the SAA from below using weather balloons equipped with radiation sensors.  Next week we will share the results of our first flight from a launch site in Chile.  Stay tuned!
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On Oct. 1st, 2016, Earth weather met space weather above Hurricane Matthew.  As the giant storm system was approaching the Greater Antilles, Frankie Lucena of Puerto Rico photographed red sprites shooting up from the thunderclouds:

Sprites are a strange and beautiful form of lightning that shoot up from the tops of electrical storms. They reach all the way up to the edge of space alongside meteors, auroras, and noctilucent clouds. Some researchers believe cosmic rays help trigger sprites, making them a  true space weather phenomenon.

Seeing sprites above a hurricane is rare. Most hurricanes don't even have regular lightning because the storms lack a key ingredient for electrical activity: vertical winds. (For more information read the Science@NASA article "Electric Hurricanes.") But Matthew is not a typical hurricane.  It's one of the most powerful in recent years, briefly reaching Category 5 at about the time Lucena photographed the sprites.  Perhaps extra-strong winds in the vicinity of the storm set the stage for upward-reaching bolts.

Sprite photographers across the Caribbean and the southeastern USA should be alert for more as the storm system approaches the mainland: observing tips.
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