Armenia on Monday celebrates Astronomy Day; traditionally, various thematic events are organized on this day.

It was decided to mark Astronomy Day in Armenia on September 18, since renowned Armenian scientist, one of the founders of theoretical astrophysics, and National Hero of Armenia, Academician Victor Ambartsumian was born on this day in 1908 in Tbilisi, the capital city of Georgia, according to Calend.ru.

Ambartsumian worked in the field of physics of stars and nebulae, stellar astronomy, dynamics of stellar systems and cosmogony of stars and galaxies, and contributed to mathematical physics.