solar ejection

Sunspots are localized regions of extremely intense magnetic fields. These magnetic fields intertwine, and the resulting magnetic energy can generate a sudden, violent release of energy called a solar flare.

A flare is called a coronal mass ejection (CME), an expanding bubble of charged particles that race outward. Flares release energy in many forms - electro-magnetic (Gamma rays and X-rays), energetic particles (protons and electrons), and mass flows. It arrives at earth 18-36 hrs. after leaving the sun. Light and other radiation travels from the Sun to Earth in about 8 minutes.

The Solar and Heliospheric Observatory (SOHO) coronagraphs captured this movie of a coronal mass ejection heading toward Earth on Oct. 22nd 2003.

aurora, northern lights
Aurora, also called the Southern and Northern Lights, are created when the charged solar particles stream down Earth's magnetic field lines and excite oxygen and nitrogen atoms in the atmosphere. Normally the aurora are only visible from places near the poles, like Alaska. But when Earth's magnetic field is overwhelmed, the aurora can dip will into the United States and Europe.

Astronomers rank solar flares into five categories according to the extent to which they emit X-rays. Class X is the most powerful, being tens times the intensity of M-class flares. Flares are characterized by their brightness in X-rays (X-Ray flux), the GEOS Class. The biggest flares are X-Class flares. M-Class flares have a tenth the energy and C-Class flares have a tenth of the X-ray flux seen in M-Class flares.

The sun has an average 11-year cycle of behavior which is projected to peak in 2013.

One on March 6, 1989 knocked out power to the Canadian province of Quebec.

One on July 14-16 was in science.nasa.gov/science-news:

"Forecasters say Solar Max is due in the year 2013. When it arrives, the peak of 11-year sunspot cycle will bring more solar flares, more coronal mass ejections, more geomagnetic storms and more auroras than we have experienced in quite some time.

On the weekend of July 14, 2012, sky watchers around the world got a taste of things to come.

It was mid-Saturday in North America when a coronal mass ejection or "CME" crashed into Earth's magnetic field and triggered the most sustained display of auroras in years. For more than 36 hours, magnetic storms circled Earth's poles. Northern Lights spilled across the Canadian border into the United States as far south as California, Colorado, Kansas, and Arkansas. In the southern hemisphere, skies turned red over Tasmania and New Zealand, while the aurora australis pirouetted around the South Pole."

See video at science.nasa.gov/science-news

In 1997, an AT&T Telestar 401 satellite used to broadcast television shows from networks to local affiliates was knocked out during a solar storm. In May 1998 a solar blast disabled PanAmSat's Galaxy IV. Among the casualties: automated teller machines; gas station credit card handling services; 80 percent of all pagers in the United States; news wire service feeds; CNN's airport network; and some airline weather tracking services.

A space storm also heats the upper level of Earth's atmosphere, causing it to expand. That's no good for satellites that can get caught up in air that didn't used to be there. Communication disruptions can occur without actually damaging satellites. Even cell phone towers can be zapped, causing dropped calls.

The greatest solar storm on record (prior to the Nov. 2003 storm) occurred in 1859, shorting out telegraph wires and starting fires in the United States and Europe. Paal Brekke, SOHO deputy project scientist, told SPACE.com this week's storm, if it hooks up with Earth in just the right way, would be about one-third as strong as the 1859 tempest.

The magnetic orientation of the CME relative to the Earth's magnetic field affects the intensity of the flare.

Flares are characterized by their brightness in X-rays (X-Ray flux), the GEOS Class. The biggest flares are X-Class flares. They are major events that can trigger radio blackouts around the whole world and long-lasting radiation storms in the upper atmosphere.
M-Class flares have a tenth the energy. They generally cause brief radio blackouts that affect Earth's polar regions. Minor radiation storms sometimes follow an M-class flare.
C-Class flares have a tenth of the X-ray flux seen in M-Class flares. They have with few noticeable consequences here on Earth.

Strength is also determined by magnetic field strength of the solar wind measured in nT (nano-Teslas)
DateStrength
1859 -1,760 nT.
1989 -589 nT / X15
Jun. 1991 X12
Oct. 1991 X6
Nov. 1997 X9
Aug. 1998 X5
July 2000 dubbed the Bastille Day event
April 2, 2001 > X17 Not pointed at Earth
Oct. 2003 X17 (may be the third strongest X-flare on record)
- There were no significant effects.
Nov. 2003 X28 - Largest ever. Only part of the CME is directed towards Earth, so we will receive only a glancing blow, since the source region is pointing away from us on the right on the limb of the Sun as seen from Earth.
Oriented Scintillation Spectrometer Experiment (OSSE) Solar Flare Observations at nrl.navy.mil

See:
Astronomical Events
http://news.bbc.co.uk/1/hi/sci/tech/411005.stm
http://www.space.com/scienceastronomy/solar_flare_031028.html
http://spaceweather.com/
http://www.sec.noaa.gov/
LASCO Coronal Mass Ejections Lists at nrl.navy.mil
http://www.sec.noaa.gov/SWN/
"Stormy Star", National Geographic, July 2004


last updated 27 June 2004