Month: February 2018

Earth’s Magnetic Field is Ringing Like a Bell

/ Dr.Tony Phillips / Leave a comment

 Feb. 22, 2018: Today, a high speed solar wind stream is passing just south of Earth, making grazing contact with our planet’s magnetic field. This is causing something unusual to happen. Around the poles, Earth’s magnetic field has been ringing like a bell. Rob Stammes recorded the phenomenon from his magnetic observatory in Lofoton, Norway.

“Ths morning, the magnetic field around our observatory (as measured by ground currents) was swinging back an forth with a 100 second period,” says Stammes. “This very stable oscillation went on for more than an hour.”

This is quite different from what normally happens when a solar wind stream hits Earth’s magnetic field. Here is an example of Stammes’ recordings during a regular geomagnetic storm. Compared to the cacophany of a normal storm, this morning’s event was a sweet pure tone.

Researchers call these pure ultra-low frequency oscillations “pulsations continuous” (Pc). Pc waves have an energizing influence on particles in Earth’s inner magnetosphere because they resonate with the natural motion of particles around the geomagnetic field. This, in turn, can supercharge the aurora borealis.

Some of the energy injected by Pc waves is being observed right now in Sweden. “The auroras are going crazy!” reports Chad Blakley of Lights over Lapland, who roared out on his snowmobile to photograph the display:

“The lights were so impressive that I forgot that I was only wearing jeans before heading out! It may have been -25 degrees outside but it was worth 15 minutes in the cold to see a display that I will never forget,” says Blakley.

The effect of this solar wind stream may be likened to a person blowing across the top of a soda bottle, the glancing breath producing a nearly monochromatic waveform. “This is quite rare,” says Stammes. “Pulsating continuous signals like these are visible only 2 or 3 times a year.”

Stay tuned for more “ringing auroras” in the hours ahead. Free: Aurora Alerts

Realtime Aurora Photo Gallery

Rads on a Plane: The Data

/ Dr.Tony Phillips / 1 Comment

Feb. 21, 2018: Many people think that only astronauts have to worry about cosmic radiation. Not so. Ordinary air travelers are exposed to cosmic rays, too. On a typical flight over the continental USA, radiation dose rates in economy class are more than 40 times higher than on the ground below. Cosmic rays penetrate the walls of aircraft with ease. This has  prompted the International Commission on Radiological Protection (ICRP) to classify pilots as occupational radiation workers–just like nuclear power plant engineers.

Since Jan. 2015, Spaceweather.com and the students of Earth to Sky Calculus have been monitoring cosmic rays in airplanes. Our method is simple: We board planes carrying the same cosmic ray payload we routinely fly to the stratosphere on space weather balloons. Inside the airplane we measure X-ray, gamma-ray and neutron dose rates along with GPS altitude, latitude and longitude

flightpaths
Above: Flight paths forming the basis of our aviation radiation study. 2015-2017

Three years after our first flight, our data set is impressive. We have 14,183 GPS-tagged radiation measurements collected during 67 flights over 2 oceans and 5 continents. We have spent 236.4 hours onboard planes taking data. If you accumulated that into a single flight, it would amount to 9.8 uninterrupted days on a plane.

This substantial data set is allowing us to explore how radiation varies with altitude around the globe. It’s not the same everywhere. The Arctic, for example, differs sharply from the equator, and there are interesting departures from “normal” near the South Atlantic Anomaly. We’re also discovering how Earth’s natural magnetism shields travelers from radiation: there’s a strong correlation in our data between dose rate and the geomagnetic field around the airplane.

Best of all, we can now predict dose rates for flights that haven’t even taken off yet. Using the data from 2015-2017, we’re building an empirical predictive model and actively testing it against new flights in 2018. Early results show that it works well over the continental USA, and we are beginning to check international flights, too.

Stay tuned for updates!