Equinox Sun

Autumn Arrives

Nearly a month has passed since my last solar observing session. Conditions finally improved on September 22nd, the day of the autumnal equinox. The sky cleared for only a few morning hours before clouds eventually returned in the afternoon. Temperature was in the 70's while breezes ruffled papers. Short episodes of steady atmosphere existed between mostly mediocre seeing. I observed for nearly an hour beginning at 11:55 am EDT, just 10.5 hours before the exact time of the equinox. At noon the Sun's center was only about 10 arc minutes north of the celestial equator!

A few decent sunspots and filaments were scattered about the solar disc, but none were truly spectacular. The first image below, a 24-image mosaic made with a 2X Barlow lens, shows the Earth-facing side of the Sun on September 22nd. An impressive dark filament on the Sun's left (east) side is the most striking feature. (Click on the image for a larger view.)

The southeastern portion of the Sun, shown in the next 3-image mosaic, had the majority of interesting features. The long dark filament was an enormous prominence on the Sun's limb a few days before September 22nd. Two days after September 22nd the long prominence to the lower left of the sunspots also became a large filament when it rotated onto the solar disc.

The next two images were made by stacking 100 of the best frames from a 1,000-frame video. These pictures show good detail because seeing was good during most of the time the video was recorded. The first image shows sunspots 2170 (above) and 2169 (below) split by a horizontal filament.

Notice the structure to the left of the horizontal dark filament. It looks very much like the shape of magnetic field lines around the north and south poles of a bar magnet!

Gases shaped by magnetic fields on the Sun

Iron filings reveal the shape of a bar magnet's magnetic field

The group of sunspots near the southeastern limb are shown next in good detail.

Finally, here's a nice prominence hanging below the Sun's southern limb.

October usually brought clear weather at my old home in Lynchburg. I wonder if this will be true in Williamsburg.
 

Tiny Flare

Sunspot Movie

It's been a long time since I tried to make a solar movie. During my last observing session, on August 27th, I tried watching sunspot 2149 where some rapid motion had just occurred. Unfortunately, nothing huge and dramatic happened while I watched. Beginning at noon EDT I recorded 400-frame videos, one every 60 seconds, for 30 minutes. After 30 minutes, nothing seemed to be happening, so I stopped recording. There were enough videos to construct 31 still frames for the following time-lapse movie which condenses 30 minutes of solar activity into about 3 seconds. The movie runs over and over in a continuous loop.

Some things to notice:

• The brief white outburst of a tiny flare to the left of the sunspot.
• The darkest central part of the sunspot, the umbra, is not uniformly dark, but, instead, broken into detailed dark segments.
• Two small, dark features shoot radially outward to the right of the umbra through the penumbra, the light annular region surrounding the umbra.
• The penumbra also displays outward moving penumbral waves like those from a stone dropped in a pond.  

(Be patient while the movie loads. if it doesn't play automatically, click on it.)