Welcome to the homepage of the Solar Observation in Bulgaria - SOB

SOB is the solar physics project of the National Astronomical Observatory (NAO) Rozhen. The project is part of the research activities of the Department 'Sun and Solar System' at the Institute of Astronomy (IA) and NAO Rozhen, Bulgarian Academy of Sciences.

Main Factors Influencing Climate Change: A Review


Todor Nikolov, Nikola Petrov

Solar cycle


Best astronomy events for 2013

Here are the most spectacular astronomical events expected for 2013.

Selected are no more than one event per month and additional information is given.


Astronomy Calendar of Celestial Events 2013

Astronomy Calendar 2013

The Astronomy calendar includes data for some general celestial events during 2013. In all reports, time and date are in universal time (UT) calculated for Sofia, Bulgaria. More reports generated by Astronomy Lab 2 for Windows, marked on the page as astron.lab. Time is in 24 hour format.



Abbreviations used in reports:

AU                        – Astronomical Units (150 000 000 km)

Site anouncement

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And the comments are moderated again, enough spam.
Happy holidays everyone.

Doomsday on 21 December 2012 - End of the world or the day of misunderstanding?

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Doomsday on 21 December 2012 - End of the world or the day of misunderstanding?


Powerful solar explosions, blasts of supernovae or gamma bursts of stars are certain factors for the occurrence of wildlife on Earth. All these factors could lead to rapid mutation pattern and great biodiversity. Of course, we

Total Lunar Eclipse on 10 Dec 2011

The total Lunar eclipse on 10 Dec 2011 was an unusually phenomenon for observers in Bulgaria. In the moment of sunset the Moon rises on the horizon obscured by Earth’s shadow.

Fig. 1. Eclipse of the Moon on 10Dec 2011. CANON 1Ds MarkII, with 400 mm F/5.6 lenses, 1/8 sec. at 3200 ISO.

Frost Flower and Ice Ribbons

At middle latitudes or high altitudes in autumn conditions arise in which we can observe ribbons ice formations. In late October and early November 2011 immediately above the ground around the stems of some plants appeared icy ribbons.

Fig. 1. Ice ribbons

Iridescent Moon ring

Often we can see an iridescent crown (ring or halo) around the Moon. From time immemorial, this phenomenon is related to the culture of many nations, a harbinger of cold, rain or snow. But often the beauty of nature is short and portends bad weather.

Fig.1. Iridescent crown around the Moon (06 Nov 2011).

Iridescent cloud over the Rila Mountain

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Iridescent cloud

Canon PowerShot SX10 IS, focal length: 40mm, f/5.0, exp. time: 1/640 sec, ISO: 80

28 Oct 2011 06:49 UT, photo: Anton Stoychev


The Green Flash Phenomenon

"Ever gazed upon the green flash, Master Gibbs?"
"I reckon I've seen my fair share. Happens on rare occasion; the last glimpse of sunset, a green flash shoots up into the sky. Some go their whole lives without ever seeing it. Some claim to have seen it who ain't. And some say... "
"It signals when a soul comes back to this world, from the dead!

― Hector Barbossa, Joshamee Gibbs and Pintеl to Will Turner. Pirates of the CaribbeanAt Worlds End

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