Jellyfish Sprites over Oklahoma

May 25, 2018: Last night, a swarm of luminous jellyfish appeared over Oklahoma. “A swarm of jellyfish sprites, that is,” says Paul Smith, who photographed them rising above an intense thunderstorm near Oklahoma City:

“The sprites were about 80 miles away from me,” says Smith. “At that distance I could see over the tops of the storm cells where the jellyfish appear. I’ve photographed many sprites from 200 to 300 miles away. These, however, were unusually nearby, and they are my best pictures yet.”

Sprites are an exotic form of upward directed lightning. Although the forms have been seen for at least a century, many scientists did not believe they existed until after 1989 when sprites were photographed by cameras onboard the space shuttle. Now “sprite chasers” like Smith routinely photograph them from their own homes.

“I have been recording sprites since last summer when I accidentally caught a few during the Perseid meteor shower,” says Smith. “I have a couple of hundred events on camera now and I am out almost every night there are storms in my vicinity. This month I have driven for five hours some nights trying to find a clear view over active cells.”


The blue pushpin is Smith’s location; the arrow points to the sprites he saw on May 24, 2018.

Oklahoma is the epicenter of a region that we call “Sprite Alley”–a corridor stretching across the US Great Plains where intense thunderstorms produce lots of upward directed lightning. Already this year we have received reports of sprites and their stronger cousins, Gigantic Jets, from Texas to Nebraska. And summer thunderstorm season isn’t even fully underway yet.

Some researchers think that sprites may be linked to cosmic rays: Subatomic particles from deep space strike the top of Earth’s atmosphere, producing secondary electrons that trigger the upward bolts. If this is true, then sprites could multiply in the months and years ahead as cosmic rays intensify due to the decline of the solar cycle. More sprite images may be found on Paul Smith’s Facebook page.

Realtime Sprite Photo Gallery

Lunar Eclipses and Climate Change

May 24, 2018: Strange but true: You can learn a lot about Earth’s climate by watching a lunar eclipse. This week at the 46th Global Monitoring Annual Conference (GMAC) in Boulder, CO, climate scientist Richard Keen of the University of  Colorado announced new results from decades of lunar eclipse monitoring.

“Based on the color and brightness of recent eclipses, we can say that Earth’s stratosphere is as clear as it has been in decades. There are very few volcanic aerosols up there,” he explains. This is important, climatologically, because a clear stratosphere “lets the sunshine in” to warm the Earth below.

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To illustrate the effect that volcanic aerosols have on eclipses, Keen prepared a side-by-side comparison (above) of a lunar eclipse observed in 1992 after the Philippine volcano Pinatubo spewed millions of tons of gas and ash into the atmosphere vs. the latest “all-clear” eclipse in January 2018.

“Compared to the murky decades of the el Chichon and Pinatubo, the clear stratosphere since 1995 has allowed the intensity of sunlight reaching the ground to increase by about 0.6 Watts per square meter,” says Keen. “That’s equivalent to a warming of 1 or 2 tenths of a degree C (0.1 C to 0.2 C).”

“In other words,” he adds, “over the past 40 years, the decrease of volcanic aerosols and the increase of greenhouse gases have contributed equally to the total warming (~0.3 C) observed in global satellite temperature records.”

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Total lunar eclipses happen somewhere on Earth typically once or twice a year. Keen is looking forward to the next one on July 27, 2018, which will be the longest lunar eclipse of the century. The Moon will pass almost directly through the middle of Earth’s shadow, remaining inside for 1 hour and 43 minutes. That’s just a few minutes shy of the theoretical maximum.

“This will give us plenty of time to measure the color and brightness of Earth’s shadow and, thus, the aerosol content of the stratosphere,” says Keen.

For more information about lunar eclipses and climate change, check out Keen’s poster from the GMAC.

Atmospheric Radiation Update

May 21, 2018: Cosmic rays over California continue to intensify, according to high-altitude balloons launched by Spaceweather.com and the students of Earth to Sky Calculus. We’ve been monitoring secondary cosmic rays in the stratosphere with regular launches from Bishop CA since 2015. In the data plot below, 3 of the 4 highest radiation measurements have occurred just in the past few months:

The worsening cosmic ray situation is linked to the solar cycle. Right now, the sun is heading toward a deep Solar Minimum. As the outward pressure of solar wind decreases, cosmic rays from deep space are able to penetrate the inner solar system with increasing ease. This same phenomenon is happening not only above California, but all over the world.

Take another look at the data plot. The general trend in radiation is increasing, but it is not perfectly linear. From launch to launch we see significant up and down fluctuations. These fluctuations are not measurement errors. Instead, they are caused by natural variations in the pressure and magnetization of the solar wind.

How does the overall increase affect us? Cosmic rays penetrate commercial airlines, dosing passengers and flight crews enough that pilots are classified as occupational radiation workers by the International Commission on Radiological Protection (ICRP). Some research suggests that cosmic rays can seed clouds and trigger lightning, potentially altering weather and climate. Furthermore, there are studies ( #1, #2, #3, #4) linking cosmic rays with cardiac arrhythmias in the general population.

The sensors we send to the stratosphere measure X-rays and gamma-rays, which are produced by the crash of primary cosmic rays into Earth’s atmosphere. The energy range of the sensors, 10 keV to 20 MeV, is similar to that of medical X-ray machines and airport security scanners. Stay tuned for updates as the monitoring program continues.

What is the Da Vinci Glow?

May 15, 2018:  Five hundred years ago, Leonardo da Vinci proposed an outlandish theory explaining why the Moon’s surface glows after lunar nightfall. Turns out, his idea was correct. The Da Vinci Glow–also known as “Earthshine”–makes the entire lunar disk visible even when the sunlit fraction is just a few percent.

For much of human history, people marveled at the faint image of the full Moon inside the arms of the crescent. Where did it come from? No one knew until the 16th century when Leonardo figured it out. He realized that sunlight reflected from Earth lit up the lunar night.


Above: Da Vinci’s sketch of Earthshine in 1510 vs. Italian astronomer Riccardo Di Nasso’s photo of Earthshine in 2006.

Visualizing this in the 1500s required a wild kind of imagination. No one had ever been to the Moon and looked “up” at Earth. Most people didn’t even know that Earth orbited the sun. Copernicus’ sun-centered theory of the solar system wasn’t published until 1543, twenty-four years after Leonardo died.

Wild imagination was one thing Leonardo had in abundance. His notebooks are filled with sketches of flying machines, army tanks, scuba gear and other fantastic devices centuries ahead of their time.

In Leonardo’s Codex Leicester, circa 1510, there is a page entitled “Of the Moon: No Solid Body is Lighter than Air.” He states his belief that the “ghostly glow” is due to sunlight bouncing off Earth’s oceans and, in turn, hitting the Moon. 500 years later, we know that Earth’s clouds (not oceans) do most of the reflecting; but that is a quibble. Leonardo understood the basics well enough.

Go outside and look at the next crescent Moon. The Da Vinci Glow is waiting….

STEVE Visits the USA

May 6, 2018: On Saturday, May 5th, a stream of solar wind engulfed Earth, sparking G1 and G2-class geomagnetic storms through the weekend. High atop Earth’s atmosphere, hot ribbons of plasma began to flow through our planet’s magnetic field. Suddenly, STEVE appeared. Alan Dyer photographed the mauve ribbon of light over Gleichen, Alberta:

“STEVE, the strange auroral arc, put in quite the appearance on Sunday night, with a fine show over southern Alberta lasting about an hour,” says Dyer. “It started as a faint arc in the east, then intensified, cutting across the entire sky.”

STEVE (Strong Thermal Emission Velocity Enhancement) was discovered by sky watchers in Alberta only a few years ago, although the phenomenon was surely active long before. The narrow ribbon is related to auroras, but has a distinct shape, color, and habitat. Researchers are now beginning to understand STEVE as a manifestation of hot plasma currents in the upper atmosphere.

Elizabeth MacDonald of NASA’s Goddard Space Flight Center recently published a paper on STEVE. In it, they link STEVE to a phenomenon called “subauroral ion drifts” (SAIDs). Satellites have tracked thousands of SAIDs: They tend to appear most often during spring and fall and seem to prefer latitudes near +60 degrees.

This weekend, STEVE traveled farther south than usual. Greg Ash saw the ribbon over Ely, Minnesota, at latitude +47.9 N:

“As you can imagine, I was totally stoked,” says Ash. “This was my first STEVE sighting and it was unforgettable. It was visible with the naked eye and I could see the pulsations of green with the purple.”

Elsewhere, STEVE was sighted in Tofte, Minnesota (+47.6N), Buxton, North Dakota (+47.6 N), Arcadia, Michigan, (+44.5N) and Fort Frances, Ontario (+48.6N). These relatively low latitude apparitions are an encouraging sign for sky watchers who wish to see the strange ribbon for themselves. You don’t have to travel to the Arctic Circle to meet STEVE. He might be coming to you. Free: Aurora Alerts.

Realtime STEVE Photo Gallery

Sunspots Vanishing Faster than Expected

May 1, 2018: Sunspots are becoming scarce. Very scarce. So far in 2018 the sun has been blank almost 60% of the time, with whole weeks going by without sunspots. Today’s sun, shown here in an image from NASA’s Solar Dynamics Observatory, is typical of the featureless solar disk:

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The fact that sunspots are vanishing comes as no surprise. Forecasters have been saying for years that this would happen as the current solar cycle (“solar cycle 24”) comes to an end. The surprise is how fast.

“Solar cycle 24 is declining more quickly than forecast,” announced NOAA’s Space Weather Prediction Center on April 26th. This plot shows observed sunspot numbers in blue vs. the official forecast in red:

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“The smoothed, predicted sunspot number for April-May 2018 is about 15,” says NOAA. “However, the actual monthly values have been [significantly] lower.”

“Official” forecasts of the solar cycle come from NOAA’s Solar Cycle Prediction Panel–a group of experts from NOAA, NASA, the US Air Force, universities and other research organizations. They have been convening at intervals since 1989 to predict the timing and intensity of Solar Max. The problem is, no one really knows how to predict the solar cycle. The most recent iteration of the panel in 2006-2008 compared 54 different methods ranging from empirical extrapolations of historical data to cutting-edge supercomputer models of the sun’s magnetic dynamo. None fully described what is happening now.

It’s important to note that solar minimum is a normal part of the sunspot cycle. Sunspots have been disappearing (or nearly so) every ~11 years since 1843 when German astronomer Samuel Heinrich Schwabe discovered the periodic nature of solar activity. Sometimes they go away for decades, as happened during the Maunder Minimum of the 17th century.  We’ve seen it all before. Or have we….?

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Researchers are keeping a wary eye on the sun now because of what happened the last time sunspots disappeared. The solar minimum of 2008-2009 was unusually deep. The sun set Space Age records for low sunspot number, weak solar wind, and depressed solar irradiance. When the sun finally woke up a few years later, it seemed to have “solar minimum hangover.” The bounce-back Solar Max of 2012-2015 was the weakest solar maximum of the Space Age, prompting some to wonder if solar activity is entering a  phase of sustained quiet. The faster-than-expected decline of the sunspot cycle now may support that idea.

Newcomers to the field are often surprised to learn that a lot happens during solar minimum: The sun dims, albeit slightly. NASA recently launched a new sensor (TSIS-1) to the International Space Station to monitor this effect. With less extreme UV radiation coming from the sun, Earth’s upper atmosphere cools and shrinks. This allows space junk to accumulate in low Earth orbit.

neutrons_stripAbove: A neutron bubble chamber in an airplane 35,000 feet above Greenland. Spaceweather.com and the students of Earth to Sky Calculus are flying these sensors to measure aviation radiation during solar minimum. [more]

The most important change, however, may be the increase in cosmic rays. Flagging solar wind pressure during solar minimum allows cosmic rays from deep space to penetrate the inner solar system. Right now, space weather balloons and NASA spacecraft are measuring an uptick in radiation due to this effect. Cosmic rays may alter the chemistry of Earth’s upper atmosphere, trigger lightning, and seed clouds.

Air travelers are affected, too. It is well known that cosmic rays penetrate airplanes. Passengers on long commercial flights receive doses similar to dental X-rays during a single trip, while pilots have been classified as occupational radiation workers by the International Commission on Radiological Protection (ICRP). Ongoing measurements by Spaceweather.com and Earth to Sky Calculus show that dose rates at cruising altitudes of 35,000 feet are currently ~40 times greater than on the ground below, values which could increase as the solar cycle wanes.

Solar minimum is just getting started. Stay tuned for updates.