At 03:56 UTC today the Sun sent us its best equinox wishes with moderately strong M1.7 solar flare originating from Region 2010 (S15E27, Dac/beta). This was the largest event on the Sun in last 24 hours (by 12:30 UTC) and it was associated with a Type II radio sweep observed at 03:52 UTC (~372 km/s) and a Type IV sweep at 04:07 UTC - suggesting an associated CME from the event.
NASA SOHO LASCO C2/C3 and NASA STEREO A/B coronagraphs depicted a slow moving CME of the East limb from Earth's perspective. Initial analysis of the event suggests that it is unlikely to have a component on the Sun-Earth line.
You can see the eruption in the video below. What seems like a glitch around 07:00 UTC is actually our planet passing between the SDO (Solar Dynamics Observatory) and the Sun.
Video courtesy: коля павл. (via Helioviewer)
A pair of dark magnetic filaments are stretching across the almost-entire circumference of the Sun's southern hemisphere. NASA's Solar Dynamics Observatory took this picture on March 19, 2014:
Image credit: NASA SDO / Edit: SpaceWeather
Sometimes, magetic filaments such as these become unstable and collapse. This can lead to a Hyder flare - a type of explosion that does not require sunspots. Hyder flares this week would likely be Earth directed as the filaments are both facing our planet.
A ~10 degree filament that was located along a magnetic boundary near N15W15 erupted at around 07:00 UTC today. Coronagraph data from the time period shortly after does not indicate a CME from the event, nor any other clearly Earthward transients in last 24 hours.
There are currently 8 numbered sunspot regions on the Earth side of the Sun.
Region 2010, the source of todays M1.7 solar flare, shows continued signs of modest growth. Other regions were stable and overall unremarkable.
Sunspots on March 20, 2014. Image credit: SDO HMI
2002 S18W86 328 30 4 CAO 2 B
2004 S10W59 301 60 5 DAO 9 B
2005 N13W23 265 250 3 HHX 1 A
2008 S11E17 225 30 4 CRO 6 B
2010 S15E39 203 100 7 DAI 13 B
2011 S07W36 278 70 6 DAO 9 B
2012 S09E47 195 10 1 AXX 2 A
2013 N13E56 186 30 2 HSX 1 A
2014 S15E74 168 50 5 CSO 4 B
Solar activity is expected to be low with a chance for more M-class activity for the next three days. NOAA SWPC forecasters estimated 40% chance for M-class, and 1% chance for X-class solar flare for the next three days (March 20 - 22).
The greater than 2 MeV electron flux at geosynchronous orbit is expected to remain at normal levels. The greater than 10 MeV proton flux at geosynchronous orbit is expected to remain at background levels (below S1-Minor).
Solar wind conditions are expected to remain nominal.
The geomagnetic field was quiet in last 24 hours and is expected to be at mostly quiet levels for the next three days.
Vernal/autumnal equinox - March 20, 2014
Illumination of Earth by Sun on the day of equinox (vernal and autumnal). During an equinox, the Earth's North and South poles are not tilted toward or away from the Sun, and the length of the day is theoretically the same at all points on Earth's surface. Image by Przemyslaw "Blueshade" Idzkiewicz.
At 16:57 UTC today the Sun will cross directly over the Earth's equator. This moment is known as the vernal equinox in the Northern Hemisphere and autumnal equinox in the Southern Hemisphere. This is also the beginning of spring in the Northern Hemisphere and autumn in the Southern Hemisphere.
At the equinox, Earth’s two hemispheres are receiving the Sun’s rays equally - night and day are approximately equal in length. This phenomenon can occur on any planet with a significant tilt to its rotational axis.
Spring and autumn are also aurora seasons
For reasons not fully understood by scientists, the weeks around the vernal equinox are prone to Northern Lights. (Science@NASA)
"It turns out that rope-like magnetic connections between Sun and Earth are favored in springtime. It's a matter of geometry: As Earth goes around in its orbit, Earth's tilted magnetic poles make different angles with respect to the Sun, tipping back and forth with a one-year cadence. Around the time of the equinox, Earth's magnetic field is best oriented for "connecting-up" with the Sun.
But wait, there are two equinoxes, spring and fall, with similar magnetic geometry. Indeed, studies show that fall is aurora season, too. Geomagnetic disturbances are almost twice as likely in spring and fall vs. winter and summer, according to 75 years of historical records analyzed by solar physicist David Hathaway of the Marshall Space Flight Center: diagram."
Featured image: Earth passing betweend SDO and Sun on March 20, 2014.