Space Weather Update: 03/11/2017
By Spaceweather.com, 03/11/2017
NEUTRONS ON A PLANE: Want to experience space weather? It’s easy. Just step on board an airplane. Cosmic rays from deep space penetrate Earth’s atmosphere where air travelers absorb them during long trips. On March 9th, the students of Earth to Sky Calculus flew to Sweden for an Arctic space weather balloon launch. During the flight from Los Angeles to Stockholm, they used a bubble chamber to search for neutrons–and they found them. In this photo, each bubble (three are circled for illustration) shows where a neutron passed through the chamber and vaporized a superheated droplet:
Among researchers it is well known that neutrons are an important form of cosmic rays, providing much of the biologically effective radiation dose at altitudes of interest to aviation and space tourism. Low-energy neutrons also cause single-event upsets in aircraft avionics.
By counting the bubbles in the chamber, it is possible to estimate the total dose of neutron radiation during our flight. The answer is 18 uSv–even more than the dose of X-rays and gamma-rays, which the students also measured. Lesson: When measuring aviation radiation, don’t forget the neutrons! Stay tuned for more results from our ongoing research trip to the Arctic Circle.
SOMETHING SPECIAL ABOUT MARCH: If you feel like March has been a good month for auroras … you’re right. According to 75 years of historical records analyzed by solar physicist David Hathaway, the months around equinoxes are almost twice as likely as solstices to have geomagnetic disturbances. Indeed, according to this plot, March may be the best month of the year for Arctic auroras:
Photo credit: Caroline/AdventureMutzz of Ersfjordbotn, Norway. Mar. 8, 2017
Researchers have long known that auroras favor equinoxes, but they didn’t fully understand why until NASA launched the THEMIS satellites 10 years ago. In 2007, THEMIS detected magnetic ‘ropes‘ occasionally connecting Earth’s upper atmosphere directly to the sun. Solar wind particles flow in along these ropes, providing energy for geomagnetic storms and auroras.
It turns out that rope-like magnetic connections between the sun and Earth are favored in spring and fall. It’s a matter of geometry: As Earth goes around in its orbit, Earth’s tilted magnetic poles make different angles with respect to the Sun, tipping back and forth with a one-year cadence. Around the time of the equinoxes, Earth’s magnetic field is best oriented for “connecting-up” with the sun.
Northern spring is coming. Arctic sky watchers, enjoy the green!
NORTHERN LIGHTS SPACE PENDANT: To raise money for their trip to the Arctic Circle, on March 2nd the students of Earth to Sky Calculus flew a payload-full of Northern Lights pendants to the edge of space above California. You can have one for $69.95. Each piece of jewelry comes with a greeting card telling the story of the pendant’s trip to the stratosphere and certifying its peak altitude: 112,200 feet above Earth’s surface.
Bonus: Would you like your pendant to fly above the Arctic Circle as well? Make a note in the COMMENTS box at checkout and we will take your pendant to Sweden for a second trip to the stratosphere.
More far-out gifts may be found in the Earth to Sky Store. All proceeds support STEM education and high-altitude ballooning.
All Sky Fireball Network
Every night, a network of NASA all-sky cameras scans the skies above the United States for meteoritic fireballs. Automated software maintained by NASA’s Meteoroid Environment Office calculates their orbits, velocity, penetration depth in Earth’s atmosphere and many other characteristics. Daily results are presented here on Spaceweather.com.
On Mar. 11, 2017, the network reported 5 fireballs.
In this diagram of the inner solar system, all of the fireball orbits intersect at a single point–Earth. The orbits are color-coded by velocity, from slow (red) to fast (blue). [Larger image] [movies]
Near Earth Asteroids
Potentially Hazardous Asteroids (PHAs) are space rocks larger than approximately 100m that can come closer to Earth than 0.05 AU. None of the known PHAs is on a collision course with our planet, although astronomers are finding new ones all the time.
On March 11, 2017 there were 1777 potentially hazardous asteroids.
Recent & Upcoming Earth-asteroid encounters:
Notes: LD means “Lunar Distance.” 1 LD = 384,401 km, the distance between Earth and the Moon. 1 LD also equals 0.00256 AU. MAG is the visual magnitude of the asteroid on the date of closest approach.
Cosmic Rays in the Atmosphere
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.
Daily Sun: 11 Mar 17
The sun is blank–no sunspots. Credit: SDO/HMI
Sunspot number: 0
What is the sunspot number?
Updated 11 Mar 2017
Current Stretch: 4 days
2017 total: 15 days (22%)
2016 total: 32 days (9%)
2015 total: 0 days (0%)
2014 total: 1 day (<1%)
2013 total: 0 days (0%)
2012 total: 0 days (0%)
2011 total: 2 days (<1%)
2010 total: 51 days (14%)
2009 total: 260 days (71%)
Updated 11 Mar 2017
Current Auroral Oval:
Coronal Holes: 10 Mar 17
There are no large coronal holes on the Earthside of the sun. Credit: NASA/SDO.
Noctilucent Clouds The southern season for noctilucent clouds began on Nov. 17, 2016. Come back to this spot every day to see the “daily daisy” from NASA’s AIM spacecraft, which is monitoring the dance of electric-blue around the Antarctic Circle.
Updated at: 02-24-2017 17:55:02
Updated at: 2017 Mar 10 2200 UTC
Updated at: 2017 Mar 10 2200 UTC