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THE SOLAR FLARE THAT WOULDN'T END: Typical solar flares are finished in a matter of minutes. On Oct. 22nd, a solar flare in the magnetic canopy of sunspot AR2434 lasted for more than 3 hours. NASA's Solar Dynamics Observatory recorded the eruption:
The peak X-ray intensity of the flare was relatively low. On the Richter Scale of Solar Flares it registered only C4.5. What the flare lacked in amplitude, however, it made up for in longevity. The hours-long blast was powerful and produced a bright CME, shown here billowing away from the sun's southwestern limb:
The CME is not heading directly for Earth. Nevertheless, it does have an Earth-directed component. NOAA forecast models suggest that the cloud will deliver a glancing blow to our planet's magnetic field on Oct. 25th. There is a 50% chance of G1-class geomagnetic storms when it arrives. Weekend auroras, anyone? Aurora alerts: text or voice
Realtime Space Weather Photo Gallery
SPACE WEATHER BALLOONING--LATEST RESULTS: 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. Our measurements show that someone flying back and forth across the continental USA, just once, can absorb as much ionizing radiation as 2 to 5 dental X-rays. Here is the data from our latest flight, Oct. 11th:
Radiation levels peak at the entrance to the stratosphere in a broad region called the "Pfotzer Maximum." This peak is named after physicist George Pfotzer who discovered it using balloons and Geiger tubes in the 1930s. Radiation levels there are more than 80x sea level.
Note that the bottom of the Pfotzer Maximim is near 55,000 ft. This means that some high-flying aircraft are not far from the zone of maximum radiation. Indeed, according to the Oct 11th measurements, a plane flying at 45,000 feet is exposed to 2.77 uSv/hr. At that rate, a passenger would absorb about one dental X-ray's worth of radiation in about 5 hours.
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.
Hey thanks! The cosmic ray research described above is 100% crowd-funded. Our Oct. 11th balloon flight was made possible by a generous donation of $500 from Spaceweather.com reader Vicki Brown. To say thanks, we flew Vicki's parents, Betty and Earl, to the edge of space:
"I am so happy to help the young scientists, and it is cool to see my folks in the stratosphere!" says Vicki.
Readers, have you ever wanted to send a loved one to the stratosphere? You can make it happen by sponsoring a cosmic ray research flight. Contact Dr. Tony Phillips for details.
Realtime Aurora Photo Gallery
Realtime Sprite 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 Oct. 23, 2015, the network reported 54 fireballs.
(23 Orionids, 23 sporadics, 3 Southern Taurids, 3 Leonis Minorids, 2 epsilon Geminids)
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 October 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.
| ||Cosmic Rays in the Atmosphere |
These measurements are based on regular space weather balloon flights: learn more.
|Situation Report -- Oct. 20, 2015 ||Stratospheric Radiation (+37o N) |
|Cosmic ray levels are elevated (+5.8% above the Space Age median). The trend is flat. Cosmic ray levels have increased +0% in the past month. |
|Sept. 06: 4.14 uSv/hr (414 uRad/hr) |
|Sept. 12: 4.09 uSv/hr (409 uRad/hr) |
|Sept. 23: 4.12 uSv/hr (412 uRad/hr) |
|Sept. 25: 4.16 uSv/hr (416 uRad/hr) |
|Sept. 27: 4.13 uSv/hr (413 uRad/hr) |
|Oct. 11: 4.02 uSv/hr (402 uRad/hr) |
RADS ON A PLANE: Spaceweather.com and the students of Earth to Sky Calculus regularly fly balloons to the stratosphere to measure cosmic rays. For the past six months, May through Oct. 2015, they have been taking their radiation sensors onboard commercial airplanes, too. The chart below summarizes their measurements on 18 different airplanes flying back and forth across the continental United States.
The points on the graph indicate the dose rate of cosmic rays inside the airplanes compared to sea level. For instance, the dose rate for flights that cruised at 40,000+ feet was more than 50x the dose rate on the ground below. No wonder the International Commission on Radiological Protection (ICRP) classifies pilots as occupational radiation workers.
Cosmic rays come from deep space. They are high energy particles accelerated toward Earth by distant explosions such as supernovas and colliding neutron stars. Astronauts aren't the only ones who have to think about them; flyers do, too. Cosmic rays penetrate deep inside Earth's atmosphere where airplanes travel every day.
This type of radiation is modulated by solar activity. Solar storms and CMEs tend to sweep aside cosmic rays, making it more difficult for cosmic rays to reach Earth. Low solar activity, on the other hand, allows an extra dose of cosmic rays to reach our planet. This is important because forecasters expect solar activity to drop sharply in the years ahead as we approach a new Solar Minimum. Cosmic rays are poised to increase accordingly.
The plot, above, tells us what is "normal" in 2015. How will it change as the solar cycle wanes? Stay tuned for regular updates.
| ||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 |