Pear Tree Observatory

Cloud cover on the morning of the 9th prevented me from catching Mercury anywhere near first or second contact during its May 2016 transit. Ultimately, the clouds started to break up about two hours into the transit. I manually started the image capture as holes in the clouds revealed the Sun but once the clouds thinned significantly, I started taking 60 second captures automatically every 5 minutes. Very few of the captures were totally free of clouds, but several had only very thin clouds visibly moving across the field of view. Unfortunately, clouds moved back in during the last 10-15 minutes of the transit preventing any images near third or fourth contact as the planet left the solar disk

This image was taken at 1011(L) just 14 minutes after mid-transit. It is the best 178 frames (20%) of the 60 second capture. The image was taken through my double stacked 60mm Hydrogen-Alpha telescope using a Point Grey Flea 3 machine vision camera.

Mercury in transit.

Mercury is the perfectly round black spot just below and left of the center of the solar disk. Other features visible are filaments (dark streaks) and plages (bright areas).

Typical cloud coverage during the transit.

Last image before the clouds closed in.

I am still working on additional images with the intent of making a composite showing the movement of Mercury across the Sun.

A quick look at the SDO web site on the morning of the 30th of January showed a very large prominence visible in the Hydrogen-Alpha image. I quickly set up my portable mount and solar telescope and was able to capture this image. I had to overexpose the disk of the Sun quite a bit in order to view the prominence. There was a fairly constant light layer of clouds in the sky above and that led to the soft focus.

Everything about the Sun is huge: temperatures, pressures, size and mass. Even though we know those fairly accurately, the Sun can still surprise. Last October the Sun sported AR 2192, the largest sunspot grouping in the last 24 years. This week the Sun exhibits one of the longest filaments ever recorded.

A filament is a portion of solar plasma that is suspended above the surface of the Sun by magnetic forces. Since it is being held above the surface it is slightly cooler making it appear darker. This one has been measured to be about 435,000 miles long. The Earth has a diameter of just under 8,000 miles and the distance from the Earth to the Moon is just under 239,000 miles. Those values put the length of the filament into perspective.

Right now, we view the filament from above. But as the Sun continues to rotate, the filament, if it survives long enough, will eventually be seen from the side. Once that happens the filament will become a prominence. A filament and a prominence are the same object, just viewed from different angles.

This image is a stack of 150 frames taken this afternoon through the PTO’s 60mm H-alpha telescope.