Dec. 27, 2018: The habits of a weatherman are hard to break–even on holiday. So it was that Dutch meteorologist Jacob Kuiper found himself outside on Christmas morning, looking up. What he saw amazed him. “The sky was filling with strange clouds,” says Kuiper. “At first I thought they were some form of cirrus, but these clouds were uncommonly wavy with unusual curls. When I saw the telltale flashes of color, I realized they must be polar stratospheric clouds (PSCs).”

Kuiper made a time-lapse video of the display. Note the hypnotic waves and how, at the 25 second mark, ordinary clouds may be seen scudding far below them:

https://player.vimeo.com/video/308454218

Polar stratospheric clouds are not your ordinary Christmas clouds. Indeed, they have little to do with regular weather, floating so high above Earth that even airplanes cannot reach them.

Normally, the stratosphere is free of clouds–completely transparent. It’s very dry up there with a wide separation between molecules of water. When the temperature drops to around -85ºC, however, those sparse molecules begin to reluctantly gather, forming crystals of ice that become PSCs.

“I have been working in the National Meteorological Office in the central part of The Netherlands (KNMI) for 40 years,” says Kuiper. “Only twice have I seen a display of stratospheric clouds this widespread. It was thrilling. I didn’t expect the stratosphere over our country to be cold enough, but one of the stratosphere scientists in our Met. Office confirmed my idea. He also was quite surprised.”

Above: PSCs inside the Arctic Circle in 2017. Photo credit: Mia Stålnacke of Kiruna, Sweden

Tiny ice crystals in PSCs can produce episodes of iridescence so brilliant that they are sometimes mistaken for auroras. The display Kuiper recorded contained only a few brief flashes of those colors–just enough for an identification.

PSCs come in two varieties: Type I contains hydrated droplets of nitric acid and sulphuric acid. These are chemicals that can destroy ozone. Indeed, an ozone hole formed over the UK in Feb. 2016 following an outbreak of Type 1 PSCs. Type II PSCs are icy and colorful, and they do little damage to the ozone layer. The clouds Kuiper witnessed may be a mixture of both.

The display was so rare that researchers in the Met Office conducted an extra round of Christmas radio soundings to probe the stratosphere. They are still processing the data, so stay tuned!

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A GIFT FROM THE EDGE OF SPACE: The students of Earth to Sky Calculus are about to kick off a new year of cosmic ray balloon launches, continuing a 5-year campaign to monitor increasing levels of radiation in Earth’s atmosphere. You can help. Buy any gift item from the Earth to Sky Store and we’ll give you 10% off to celebrate the New Year.

All items in the Earth to Sky Store have flown to the edge of space onboard cosmic ray balloons. Each one comes with a greeting card showing the item in flight and telling the story of its journey. All sales support the Earth to Sky Calculus cosmic ray ballooning program and hands-on STEM research.

Far Out Gifts: Earth to Sky Store
All sales support hands-on STEM education

Dec. 23, 2018: NASA’s New Horizons spacecraft is 12 million km from Ultima Thule and closing fast. On New Year’s Day, it will fly by the mysterious Kuiper Belt Object three times closer than it buzzed Pluto in 2015 revealing … no one knows what. In fact, the mysteries have already begun.

Long range images of Ultima Thule reveal that it has no light curve. In other words, its brightness is constant.

Above: An artist’s concept of Ultima Thule, a double-lobed object in the Kuiper Belt

“It’s really a puzzle,” says New Horizons Principal Investigator Alan Stern of the Southwest Research Institute. And here’s why:

Last year, astronomers watched a distant star pass behind Ultima Thule. Starlight winked in and out in a pattern suggesting an elongated object with two bulbous lobes. Ultima Thule could be a binary system. You would expect the reflected brightness of such an object to vary as it rotates in the sunlight. Yet Ultima Thule does not behave that way.

What’s going on? New Horizons science team members have different ideas. “It’s possible that Ultima’s rotation pole is aimed almost right at the spacecraft,” speculates Marc Buie of the Southwest Research Institute. Such an alignment, however, is unlikely.

“Another explanation,” says the SETI Institute’s Mark Showalter, “is that Ultima may be surrounded by a cloud of dust that obscures its light curve–much the same way that a comet’s coma often overwhelms the light reflected by its central nucleus.”

“A more bizarre scenario is one in which Ultima is surrounded by many tiny tumbling moons,” suggests University of Virginia’s Anne Verbiscer, a New Horizons assistant project scientist. “If each moon has its own light curve, then together they could create a jumbled superposition of light curves that make it look to New Horizons like Ultima has a small light curve.”

“It’s hard to say which of these ideas is right,” Stern says. “We’ll get to the bottom of this puzzle soon – New Horizons will swoop over Ultima and take high-resolution images on Dec. 31 and Jan. 1, and the first of those images will be available on Earth just a day later. When we see those high–resolution images, we’ll know the answer to Ultima’s vexing first puzzle. Stay tuned!”

GIFTS FROM THE EDGE OF SPACE: The students of Earth to Sky Calculus are about to kick off a new year of cosmic ray balloon launches, continuing a 5-year campaign to monitor increasing levels of radiation in Earth’s atmosphere. You can help. Buy any gift item from the Earth to Sky Store and we’ll give you 10% off to celebrate the New Year.

All items in the Earth to Sky Store have flown to the edge of space onboard cosmic ray balloons. Each one comes with a greeting card showing the item in flight and telling the story of its journey. All sales support the Earth to Sky Calculus cosmic ray ballooning program and hands-on STEM research.

Far Out Gifts: Earth to Sky Store
All sales support hands-on STEM education

Oct. 3, 2018: Many people think that only astronauts need to worry about cosmic radiation. Not so. Ordinary air travelers are exposed to cosmic rays, too. A recent study from researchers at Harvard found that flight attendants have a higher risk of cancer than members of the general population, and the International Commission on Radiological Protection has classified pilots as occupational radiation workers.

How much radiation do you absorb? SSpaceweather.com and the students of Earth to Sky Calculus have been working to answer this question by taking cosmic ray detectors onboard commercial airplanes. Flying since 2015, we have collected more than 22,000 GPS-tagged radiation measurements over 27 countries, 5 continents, and 2 oceans.

Here is what we have learned so far:

1. Radiation always increases with altitude, with dose rates doubling every 5000 to 6000 feet. This make sense: The closer you get to space, the more cosmic rays you will absorb.
2. At typical cruising altitudes, cosmic radiation is 40 to 60 times greater than natural sources at sea level.
3. Passengers on cross-country flights across the USA typically absorb a whole body dose equal to 1 or 2 dental X-rays.
4. On international flights, the total dose can increase ~five-fold with passengers racking up 5 to 6 dental X-rays.

Using our database, we can investigate patterns of radiation around the world. For instance, this plot compares aviation radiation over the tropics vs. the Arctic:

We see that the Arctic is a high radiation zone. This comes as no surprise. Researchers have long known that particles from space easily penetrate Earth’s magnetic field near the poles, while the equator offers greater resistance. That’s why auroras are in Sweden instead of Mexico. Generally speaking, passengers flying international routes over the poles absorb 2 to 3 times more radiation than passengers at lower latitudes.

We can also look at individual countries–e.g., Sweden vs. the USA vs. Chile:

As an Arctic country, Sweden has the most radiation–no surprise. The continental USA straddles the middle–again, no surprise. A mid-latitude country can be expected to have middling radiation. Chile, however, is more of a puzzle.

Although Chile does not cross the equator, it has some of the lowest readings in our database. This phenomenon is almost certainly linked to Chile’s location on the verge of the South Atlantic Anomaly–a distortion in Earth’s magnetic field that affects radiation levels. We are actively investigating the situation in Chile with additional flights, and will report results in a future blog.

Because our home base is in the USA, we spend a lot of time flying there. The US dataset is so dense, we can investigate regional differences across the country–for example, New England vs. the Southwest:

The two curves are indistinguishable below ~30,000 feet, but at higher altitudes they diverge. By the time a plane reaches 40,000 feet, it would experience 30% more radiation over New England than the same plane flying above the desert Southwest. According to our measurements so far, New England is the “hottest” region of the continental USA, radiation-wise, with the Pacific Northwest a close second.

Perhaps the most important outcome of our work so far is E-RAD–a new predictive model of aviation radiation. We can now predict dose rates on flights in areas where we have flown before. Because it is constantly updated with new data, E-RAD naturally keeps up with variables that affect cosmic rays such as the solar cycle and changes in Earth’s magnetic field.

Here is an example of a recent flight we took from Baltimore to Las Vegas, comparing E-RAD’s predictions with actual measurements:

The two agree within 10% for most of the flight. These errors are constantly shrinking as we add new readings to our database.

The results in this report are offered as a preview of what we are learning. Our database is growing almost-daily with new flights to new places, and we will have more results to share in the weeks ahead. We’ve created a website to showcase what we are learning and ultimately to let you, the reader, interact with our databases as well: RadsonaPlane.com.

Visit RadsonaPlane.com

 

When cosmic rays hit the top of Earth’s atmosphere, they create a spray of secondary radiation that rains down on the planet below. For years, the students of Earth to Sky Calculus have been measuring secondary cosmic rays on airplanes and high-altitude balloons using two types of sensors.

First, are the neutron bubble chambers:

Each bubble pictured above is formed by an energetic neutron (200 keV – 15 MeV) passing through the chamber. Counting bubbles yields the total dose. We use chambers manufactured by Bubble Technology Industries Inc. of Canada.

Second, we monitor X-rays and gamma rays using sensors based on Geiger tubes:

These are Polimaster 621M dosimeters sensitive to X-rays and gamma-rays. They sample energies between 10 keV and 20 MeV, spanning the range of medical X-ray machines, airport security devices, and “killer electrons” in Earth’s radiation belts.

Cosmic rays are a cocktail of different things: e.g., neutrons, protons, pions, electrons, X-rays, and gamma rays spanning a wide range of energies. Our sensors sample only three ingredients of that cocktail: neutrons, X-rays, gamma-rays. Furthermore, we are sampling only a relatively low range of energies. Many cosmic rays are much more energetic than the 15 MeV to 20 MeV upper limit of our detectors.

This means our data are only the tip of the iceberg.  Flight crews and passengers absorb even more radiation than we can detect.