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EARTH's MAGNETIC FIELD RINGS LIKE A BELL: In the Lofoten Islands of Norway, Spaceweather.com reader Rob Stammes operates a magnetic observatory. 24 hours a day, he measures the strength and direction of the local magnetic field as well as electrical currents running through the ground. During geomagnetic storms, his chart recordings go haywire. On Sept. 12th, something different happened. They rang like a bell:
"During the morning and especially around noon, sinusoidal pulsations appeared on my instruments," says Stammes. "The period was close to 115 seconds."
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 carves out a cavity in the surrounding solar wind. Pressure fluctuations in the solar wind can excite wave modes in this cavity much like Stammes observed. References: #1, #2, #3.
The magnetic oscillations of Sept. 12th were Pc4 waves; in other words, their frequencies fell in the range 6.7–22 mHz. Pc4 waves, and their even lower frequency cousins Pc5 waves (1.7–6.7 mHz), can have an energizing influence on particles in Earth's inner magnetosphere because the waves resonate with the natural motion of particles around the geomagnetic field.
Perhaps it is no surprise, then, that bright auroras were observed on both Sept. 11th and 12th. Ole Salomonsen photographed these from the window of an airplane just before sunrise in Norway:
"To get the shot was not easy," says Salomonsen. "I had to use a handheld camera in a moving plane! To create some darkness, I draped one of my jackets to over me and the window to prevent cabin-light reflections ruining the shot. The people sitting next to me probably must have had a good laugh :) Anyway I think it was worth it. Observing the auroras from air is definitely special."
Rob Stammes has been monitoring magnetic pulsations in Norway for years. "They seem to occur most often around the equinoxes," he says. That means we should stay tuned for more. It is aurora season, after all. Aurora alerts: text or voice
Realtime Aurora Photo Gallery
A SPACE WEATHER BALLOON AT THE EDGE OF SPACE: On Friday, Sept. 2nd, Spaceweather.com and the students of Earth to Sky Calculus launched a research balloon from the slopes of Mt. Washington in New Hampshire. En route to measure radiation at the edge of space, the balloon's payload snapped this spherical image of the Atlantic Coast of Maine:
The Atlantic Coast of Maine photographed from the stratosphere (108,000 feet) - Spherical Image - RICOH THETA
The balloon popped at an altitude of 118,000 feet, about 10 minutes after it took this picture. Parachuting back to Earth, the payload landed in a forest of tall trees not far from Tripp Pond, Maine, where a combined team of students from Southern Maine Community College and Earth to Sky Calculus recovered it for analysis.
This wasn't the only space weather balloon launched on Sept. 2nd. Earth to Sky students in California launched a second balloon at the same time. The transcontinental flight was part of an ongoing experiment to explore geographical variations in atmospheric radiation. Results? Here they are:
These profiles show the dose rate of secondary cosmic rays as a function of altitude over central California and southern Maine. Clearly, the atmosphere of Maine is more "radioactive." The reason can be found in the labels. The magnetic latitude in Maine (+54o) is higher than the magnetic latitude in California (+44o). In other words, Maine is closer to Earth's magnetic north pole where cosmic rays are more abundant.
These results are of interest to air travelers, atmospheric scientists, and operators of high-altitude drones, among others. In a few days we'll release an even bigger data set showing results from Chile, California, Oregon and Washington. Stay tuned.
More spherical images: (1) The launch site on the slopes of Mt. Washington, NH. (2) Emerging from the cloud layer over Mt. Washington, New Hampshire, the camera saw a ring of light in the clouds called a "glory."
Realtime Space Weather Photo Gallery
Realtime Sprite Photo Gallery
| ||Cosmic Rays in the Atmosphere |
Updated: Sept.3, 2016 // Next Flight: Sept. 10, 2016
Sept. 3, 2016: On Sept. 2nd, Spaceweather.com and the students of Earth to Sky Calculus conducted a successful transcontinental launch of two space weather balloons--one from New Hampshire and another from California. The New Hampshire balloon recorded the highest levels of atmospheric radiation since our monitoring program began two years ago. Students are reducing the data now, and we will report the results in the coming week.
While you wait, here is a shot of the Atlantic coast of Maine taken during the Sept. 2nd balloon flight from an altitude of 118,000 feet:
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 almost 13% 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.
THIS RESEARCH IS CROWD-FUNDED: The cosmic ray research presented on Spaceweather.com is done by students, driven by curiosity, and funded entirely by readers. Our latest flight over California on Aug. 21st was sponsored by World Tech Toys of Valencia CA. In exchange for their generous donation of $750, we flew a toy Striker Drone to the edge of space:
HD video and poster-quality images of the drone in space are now being used by World Tech Toys for marketing and outreach--an out-of-this-world bargain.
Our next flights on Sept. 2nd and Sept. 10th need sponsors. Would you like to assist? Contact Dr. Tony Phillips to make arrangements.
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 Sep. 13, 2016, the network reported 73 fireballs.
(72 sporadics, 1 September epsilon Perseid)
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]
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 September 13, 2016 there were potentially hazardous asteroids. 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.
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