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(ALMOST) NO CHANCE OF FLARES: Solar activity is very low. With no sunspots actively flaring, the sun's X-ray output has flatlined. NOAA forecasters estimate a 5% chance of M-class flares and no more than a 1% chance of X-flares on July 23rd. [forecast video] Solar flare alerts: text or voice.
GEOMAGNETIC STORM: A mild (Kp=5) geomagnetic storm broke out during the early hours of July 23rd when a disturbance in the solar wind hit Earth's magnetic field. Before sunrise, Northern Lights were sighted in multiple northern-tier US states. Sarah D'Angelo sends this picture from Paradise, Michigan:
"With the sun rising quickly, there wasn't much time to find a picturesque spot," she says. "I set a tripod in front of my house and hoped for the best. The colors were gorgeous. Very bright!"
The solar wind disturbance was likely related to a CME expected to sideswipe Earth today. High-latitude sky watchers should remain alert for auroras tonight as our planet passes through the CME's wake. Aurora alerts: text or voice.
Realtime Aurora Photo Gallery
RADS ON A PLANE: Many people think you have to be an astronaut to experience space weather. Not so. All you have to do is step onboard a commercial aircraft. This week, Spaceweather.com's Dr. Tony Phillips and the students of Earth to Sky Calculus flew across the United States to conduct a transcontinental launch of space weather balloons. They took radiation sensors onboard the plane to find out how much radiation they would absorb during the flight. Answer: quite a bit. Here are the data they collected:
Radiation levels in the cabin of the Airbus 319 (Spirit Airlines FL640) tripled within ten minutes after takeoff, and were nearly 30 times ground level by the time the plane reached cruising altitude at 39,000 feet. During the 3+ hour flight, the sensors accumulated more than a year's worth of natural radiation on the ground.
There was no solar storm in progress. The extra radiation was just a regular drizzle of cosmic rays reaching down to aviation altitudes. This radiation is ever-present and comes from supernovas, black holes, and other sources across the galaxy. Solar activity modulates the intensity of cosmic rays. Gusts of solar wind and CMEs can actually cause radiation levels to drop by sweeping aside cosmic rays near Earth. Periods of low solar activity, on the other hand, allow radiation levels to rise.
Solar activity is not the only variable: Radiation levels vary within the plane itself. Different-colored lines in the data plot, above, represent different locations inside the cabin. On this particular flight, dose rates were highest in First Class and lowest near the toilets in the rear. This gradient is not understood; presumably, it has something to do with the way the fuselage and fuel tanks interact with energetic particles. The altitude of the plane matters as well. When the cruising altitude increased about two hours into the flight, dose rates increased accordingly. All of these factors make radiation levels onboard airplanes unpredictable.
The radiation sensors are the same ones that Earth to Sky Calculus routinely flies onboard helium balloons to measure cosmic rays in the stratosphere. They 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.
Stay tuned for updates from the return flight.
Realtime Space Weather Photo Gallery
Realtime Sprite Photo Gallery
Realtime NLC Photo Gallery.
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 Jul. 23, 2015, the network reported 12 fireballs.
(10 sporadics, 2 alpha Capricornids)
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 July 23, 2015 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. | The official U.S. government space weather bureau |
| The first place to look for information about sundogs, pillars, rainbows and related phenomena. |
| Researchers call it a "Hubble for the sun." SDO is the most advanced solar observatory ever. |
| 3D views of the sun from NASA's Solar and Terrestrial Relations Observatory |
| Realtime and archival images of the Sun from SOHO. |
| from the NOAA Space Environment Center |
| the underlying science of space weather |
| Web-based high school science course with free enrollment |