Monday, March 31, 2014

X-1 Flare Yesterday with a Nice Coronal Dimming

The X-1 flare on Saturday produced a very nice example of coronal dimming. Here is a short movie showing five hours of the Sun in the AIA 193 passband. After the flare happens in the upper right quadrant at 1755 UTC on March 29, 2014, a dark region spreads over the north pole. This is a coronal dimming event. There are many ways to interpret these dimming events. Are they the edges of the coronal mass ejection that left the Sun at the time of the flare? Are they waves moving past magnetic field lines and making them sway? Whatever it is, it moves fast. Active Region 12017 is at 10°N 48°W. If something moves from there to the north pole of the Sun (90°N) in 45 minutes it had to move at about 360 km/s (800,000 mph). I only see the dimming moving north.

Wherever coronal dimmings come from, they look pretty cool.

Wednesday, March 26, 2014

Momentum Management Maneuver Today

Today at 1840 UTC (2:40 pm ET) SDO will execute a momentum management maneuver. For about 45 minutes from 1815 to 1900 UTC SDO data may be unavailable.

Wednesday, March 12, 2014

SDO on the Astronomy Picture of the Day

An very nice animation of SDO images for the month of January 2014 is featured on the Astronomy Picture of the Day for March 12, 2014. The images show the brighter active latitudes on either side of the equator, a coronal hole in the northern hemisphere, and filaments covering the disk of the Sun. In the HMI visible light image in the six-image montage you can see the sunspots that make up the active regions. The image is too small to see the faculae that go along with sunspots, but the latest HMI flattened image shows them quite well.

January's 31 days are a little longer than one solar rotation of 27.27 days. That means you see a part of the Sun that is just off limb at the beginning of the month a second time as that part of the Sun rotates back into view. Active region 11944 is present throughout the month in the southern hemisphere and reappears as AR 11967 at the end of the movie. AR 11946 grows in the northern hemisphere and will reappear as AR 11968. AR 11944 will also return as AR 11990 in late February. On February 25 it will be the location of an X-4.9 flare as it rotates back into view.

Long-lived active regions are a sign that solar maximum is here and starting to fade.

Check it out!

Wednesday, March 5, 2014

Stationkeeping Maneuver Today

Today at 2035 UTC (5:35 pm ET) SDO will execute a stationkeeping maneuver. For about 45 minutes from 2015 to 2100 UTC SDO data will be unavailable.