Follow this URL to see a YouTube video, compiled by contributor "SolarWatcher," on the X1.1 solar flare produced by AR 1515 late Friday, July 6th.
After several days of increased activity, and the release of several M-class flares on July 5th, the very Active Region 15115 (AR 1515) finally put out an X-Class solar flare on Friday, July 6th at 23:08 UTC (7:08 PM EDT). To be exact, it was an X1.1 flare. Associated with this blast is a 10cm Radio Burst, Type IV Sweep Frequency Event and a proton event is now in progress.
Along with the flare was corona mass ejection (CME), which appears to be headed to the south, away from Earth. But we might receive a glancing blow on July 8th or 9th.
Back to that proton event. It seems the CME hurled a bunch of energetic protons toward Earth, which were accelerated by the flare and guided by solar magnetic fields. The protons are currently peppering Earth-orbiting satellites, causing "snow" in imaging systems and posing a slim threat for single-event upsets (computer glitches).
This looks like a good time for a refresher on solar flares and CMEs...
Solar Flare Primer
To review, a solar flare is an explosion on the sun that occurs when the energy stored in twisted magnetic fields (usually above sunspots) is suddenly released. Flares produce a burst of radiation across the electromagnetic spectrum, from radio waves to X-rays and gamma-rays.
Solar flares are classified, from lowest to highest, as A, B, C, M and X according to the peak flux (in watts per square meter, W/m^2) of 100 to 800 picometer X-rays near Earth, as measured on the GOES spacecraft. The five categories break down as follows.
A-class: Peak flux of less than 10^-7 Watts/square meter. A-class flares produce no noticeable consequences on Earth.
B-class: Peak flux ranges from 10^-7 to 10^-6 Watts/square meter. B-class flares produce no noticeable consequences on Earth.
C-class: Peak flux ranges from 10^-6 to 10^-5 Watts/square meter. C-class flares produce few noticeable consequences
M-class: Peak flux ranges from 10^-5 to 10^-4 Watts/square meter. M-class flares can cause brief radio blackouts that affect Earth's polar regions. Minor radiation storms sometimes follow an M-class flare.
X-class: Peak flux is greater than 10^-4 Watts/square meter. X-class flare are major events that can trigger planet-wide radio blackouts and long-lasting radiation storms.
Within each category are nine subdivisions of strength. For example, C1 to C9, M1 to M9, and so on. On July 14, 2000, the sun produced a X6 flare which triggered a major radiation storm around Earth and was nicknamed the Bastille Day event.
Coronal Mass Ejection Primer
A coronal mass ejection (CME) is a massive burst of solar wind, plasma, and magnetic fields rising above the solar corona or being released into space.
CMEs are often associated with other forms of solar activity, most notably solar flares, but a causal relationship between the two has not been established. Most CMEs originate from active regions on Sun's surface, such as groupings of sunspots associated with frequent flares. Near a solar maximum — the period of greatest activity in a solar cycle — the sun produces about three CMEs every day, whereas near a solar minimum — the period of least activity in a solar cycle — there is about one CME every five days.
Now, Where Were We?...
Lots going on, now. As we get more details, we will post them here. Stay turned...
To monitor solar flare activity minute by minute, visit the "Today's Space Weather" page of NOAA's Space Weather Prediction Center, URL: www.swpc.noaa.gov/today.html .
To learn more about the sun and to stay current on solar activity, visit the mission home page of Solar Dynamics Observatory (SDO), sdo.gsfc.nasa.gov .