On July 15th, 2010 at 14:27 (LST) the ISS crossed the solar disk as seen from Varna, Bulgaria. The image was taken by Emil Ivanov with CANON 40 D camera and 840mm CANON objectve.

Sunspots observations in White-Light from the teritory of National Astronomical Observatory ROZHEN. The image was taken by Tsvetan Tsvetkov and Yovelina Zinkova with refractor telescope 80/1200 and Digital camera CANON EOS 350 D- summer astronomical scool Haskovo-Dimitrovgrad 2010.

Happy Easter

Wish you all a Merry Christmas and a Happy New Year

 The research team of the Institute of Astronomy, Bulgarian Academy of Sciences realized observations of the total solar eclipse on 22 July 2009 form Tianhungping, China.

Unfortunately, the weather condition was not perfect time for observations and was impossible to receive good photographically information.

The core makes about 2% of the Sun’s volume (core’s radius is ~1/4 Rסּ) but contains nearly half of its mass. The highest temperature is in the center ~1.55x10⁷ and decreases outwards to 9.42x10⁶ K. The high temperatures and densities provide conditions for the nuclear fusions that power the Sun. Most energy is provided from the three step process of hydrogen to helium conversion (proton-proton chain). A single proton-proton chain yields 26.73 MeV in gamma rays and ~0.5 MeV in two neutrinos.

 
This diagram shows main layers of a solar-type star. Using a neutral filter we can see from the Earth one perfect disk and this is the solar photosphere. Layers under the photosphere are invisible for us. With special instruments and filters there are possibilities to observe some phenomenon from the chromosphere (spicules, filaments, etc.). During total solar eclipses is possible to observe the solar corona.

Extraordinary halo around the Sun was observed on 24 Apr 2009 from the Observatory Rozhen.
This full circle halo was visible during the day. I've never saw it before.
The phenomenon was visible for quiet some time – more than 1 hour.