Sunspot 1476

While checking out my equipment for the Venus transit, I imaged the naked eye sunspot #1476. This active region unleashed an M5-class flare while it transited the face of the sun and its 160,000 km size was greater then a dozen Earth diameters.

Sunspots are temporary features in the Sun’s photosphere that are caused by intense magnetic field lines emerging from the interior. The spot appear dark because it is relatively cooler then the surrounding photosphere. The temperature of the spot is still approximately 4500 Kelvin.

TMB-92, f/5.5 (imaged at f/22.5) + Lunt Herschel Wedge (White light), Televue 4X Powermate, Philips ToUcam Pro II - PCVC 840K, 640x480 webcam, IR Rejection Filter, Losmandy Gemini G-11 EQ mount. Processed with Registax 5.1 and Adobe Photoshop. ATMoB Clubhouse, Westford, MA, 12 May 2012.