X-class flare at 1555 UTC (11:55 am ET)

Active region 12887 emitted an X-class flare today at 1555 UTC. There also appears to be a filament eruption (the precursor to a coronal mass ejection). This is the second X-class flare of Solar Cycle 25 (the first was on July 3, 2021.)

Before the flare a filament cam be seen over AR 12887 (in the blue circle).

The flare begins to brighten up at 1529 UTC.

The filament liftoff from the surface can be seen as the dark region a litle to the left of the flare in the third image.

The flare continues to brighten until its peak flux. Check out the flare in the Browse AIA/HMI Images at the SDO website.
Solar Cycle 25 is alive and well!

Annie Scott Dill Maunder, Solar Physicist

The Royal Greenwich Observatory (RGO) dedicated a new telescope on June 25, 2018, returning a tradition of observations to London. The telescope is called the Annie Maunder Astrographic Telescope (AMAT), in honor of Annie Maunder, a famous solar and stellar astronomer who worked at RGO from 1891 until the 1930’s.

The RGO is best known to solar scientists as the place where sunspot pictures were made from 1874 until 1976. Those photographs have been used by many scientists to understand how sunspots behave. Having photographs allows us to go back and remeasure the sunspot properties to see if something was missed.

Annie Maunder studied the Sun at RGO. She worked with her husband (E. Walter Maunder) for many years. After they were married she was unable to get paid for her work but continued her research into the Sun, sunspots, and whether the Sun affected our climate.

Along the way, she helped develop the Butterfly Diagram (1904 and 1922), wrote a popular book on the Sun (1908), and examined the Maunder Minimum, the period from 1645 to 1715 when few sunspots were seen and the climate in England was colder than average (1894). She traveled to far-flung places and photographed solar eclipses, all at a time when women were not supposed to do such things. Her outstanding research led to her election as a fellow of the Royal Astronomical Society in 1916, the first female ever to be admitted to the Society.

The original butterfly diagram appeared in the Monthly Notices of the Royal Astronomical Society in 1904 and again in the 1908 book The Heavens and Their Story. Here is the 1904 version, copied from the journal article. It is easy to see that sunspots follow a pattern. They start at higher latitudes at the beginning of the cycle and form at lower and lower latitudes as the sunspot cycle continues. There is nothing special about solar maximum either (the two thick lines mark solar maximum for Solar Cycles 12 and 13.) Sunspots continue to appear closer to the equator until solar minimum. Then the cycle repeats.

I used the RGO sunspot reports collated by David Hathaway to generate a modern butterfly diagram. The thick dashed line shows when RGO stopped taking data in 1976 and the US Air Force tool over. The data set continues until 2016 when Hathaway retired. Each sunspot cycle is a little different, but they all share the high latitude to low latitude progression.

We still use the butterfly diagram to study the Sun. Any paper studying the solar dynamo will probably include one just to show how well their model works. We also can use helioseismology to generate butterfly diagrams inside the Sun. These show that sunspot cycles start much earlier than sunspots can measure.

My thanks and appreciation to Annie Maunder. Please go and use the AMAT at RGO soon!

What is space weather and what research is SDO doing with space weather?

Space weather is (1) the study of eruptive solar activity (solar storms) such as solar flares, coronal mass ejections, solar energetic particles, (2) the effect these storms have on Earth, the rest of the solar system (for example the other planets) and (3) the effect on our technology in space and on Earth.

SDO has provided incredibly detailed observations of the sun and the areas that produce space weather activity. This includes observing the growth of sunspot regions (main flare and major CME producers) as well as the birth of CMEs and the evolution of solar prominences, which often produce large CMEs.  Link to larger version of the picture http://sdo.gsfc.nasa.gov/gallery/main/item/150

New Picture of the Week

Twin M-class Solar Flares

Although visually it only looks like a single flare, sensitive scientific instruments indicated that these were actually two flares very close together (June 13, 2012) from Active Region 1504.  At 12:47 UT a M1.5 solar flare started and only five minutes later a M1.9 flare erupted from the same active region. The M1.5 flare peaked at 14:08 and ended at 15:00 UT. The M1.9 flare peaked at 14:35 and ended at 15:56 UT.  The image and video clips were taken in extreme ultraviolet light.  Indicators show that the coronal mass ejection associated with these flares might impact Earth a few days later.

  Link to Quicktime Movie View Movie (QT)

German-American Day 2011 and the Discovery of the Solar Cycle

Today, October 6, 2011, is German-American Day, when we celebrate the arrival of German immigrants in Philadelphia in 1683. Germans have worked in physics for many years. Joseph Fraunhofer discovered the spectral lines in the Sun we call Fraunhofer lines. We measure the brightness, Doppler shift, and magnetic field effects of those spectral lines on SDO to study solar activity. At left we show the spectrum near the iron line at 6173 Å used by HMI to measure the velocity and magnetic field at the surface of the Sun. The slight motion to the left and right is what happens as the surface moves back and forth.


Another German, Heinrich Schwabe, wrote down the number of black specks he saw on the Sun for almost 20 years. When plotted we see the number of spots rising and falling with about a 10 year cycle. Schwabe had discovered the solar cycle. Here is a plot of Schwabe's data from his article Sonnen-Beobachtungen im Jahre 1843. The rise and fall can be seen in the crosses that show the number of spots in each year. I drew a sine curve with a 10 year period so you can see what Schwabe announced. Also called the 11-year sunspot cycle, we still measure the number of spots and produce the Sunspot Number. Along the way we have invented many more ways to measure spectra and active regions.

Happy German-American Day!

A lively active region

With a large active region currently in the northern hemisphere of the Sun, there has been a flurry of small solar flares over the past day. This larger active region may actually be comprised of four different active regions that are very close to each other forming one large, interconnected active region with multiple magnetic poles. This magnetically complex region has lead to 12 B-class and 1 C-class solar flare over the last 24 hours. Make sure to check out the daily and past 48-hour movies to see this rapidly evolving active region!

Solar Cycle 24 in the Southern Hemisphere?

Solar Cycle 24 is starting to come alive and show active regions, sunspots, flares, and CMEs. On Sunday AR 11093, the large magnetic complex in the center of this AIA 171 image from August 10, 2010, had an M-class flare. Two Earth-directed CMEs have been launched in the last 10 days. The only thing that is missing is activity in the southern hemisphere. It is normal for the two hemispheres of the Sun to reach maximum at different times, but there seems to be an increasing lag, with the southern hemisphere reaching maximum later than the northern. Stay tuned!

Check Out Our Images!

Now that the AIA and HMI data are flowing through the data system, you can look at images of the Sun and make movies of the Sun. Check out the SDO Browser at http://sdo.gsfc.nasa.gov/data/aiahmi/browse.php!

You can look at AIA images after May 20, 2010 and HMI magnetograms created after June 20, 2010. We are working to put the EVE SAM images we show on the Sun Now page into the movie database. Check out the enormous coronal hole in the northern hemisphere seen last week in AIA 193.

Enjoy!

SDO on Science Friday

SDO was featured in a video on NPR's Science Friday website (www.ScienceFriday.com). We described the Sun's magnetic field, the rise to Solar Cycle 24, and how SDO will help to understand the magnetic field. David Hathaway of NASA Marshall Space Flight Center was the guest on the show, discussing solar activity.

» Read the NPR Article.