Sunspot Comparisons

December 11, 2011

Sun 2011-11-10 (2)

FJPS-sunspotPhotographers: (top photo) Howard Cohen - (bottom photo) F. J. Pobes Serrano
Summary Authors: Howard L. Cohen; F. J. Pobes Serrano

Some predictions indicate future sunspot cycles may show declining activity. However, the current cycle seems to be gearing up with more sunspots, flares and coronal mass ejections than have been observed in several years. Even a good, small telescope (equipped with a safe solar filter) easily shows the sunspot increase. On November 10, I was helping my grandson earn his Cub Scout Belt Loop, one requirement is to set up and demonstrate how to focus a simple telescope and we decided to aim my three-inch refractor at the Sun. At least eight sunspot groups were visible with dozens of individual spots readily seen from here in Gainesville, Florida (top left image).

Compare this view with the SOHO/NASA spacecraft image taken approximately four hours earlier the same day in visible light at a wavelength of about 680 nm (top right image). This is similar to the transmission of the solar filter used on my three-inch scope. Notice the small telescope image shows not only sunspots, which are cooler than their surroundings, but also the Sun’s limb (edge) darkening. In addition, several white light faculae are visible near the left and right edges of the Sun. These are brighter and hotter areas of the Sun’s visible disk (photosphere) and best seen near the solar limb against the darker background of the limb darkening. Small scopes aren't just for kids.

The lower photo shows sunspot regions AR 1302 and 1305, observed in October 2011, in comparison to the size of the Earth.

Photo Details: Top - Unguided photo taken through a full aperture Thousand Oaks Type 2+ Glass Solar Filter (transmission 1/1,000 of 1 percent) using a Tele Vue 76 mm aperture, f/6.3 APO refractor telescope with a 480 mm focal length and equipped with a Tele Vue 4x Powermate Amplifier for an effective focal length of 1,920 mm. Camera Used: Canon EOS 5D Mark II; Exposure 1/250 at ISO 800; effective f-stop f/25; White Balance Auto. This is a single image photograph taken 2011 November 10 at 18:26 UT with some minor processing using Canon ZoomBrowser EX.

Photo Details: Inset - Telescope Orion Maksutov 180/2700 telescope; Eos 350d Camera DMK 21AF04; mount LXD 75; Photoshop; Registax and Pixinsight programs.