The International Symposium Our Non-Stable Universe dedicated to the 80th Anniversary of the Byurakan Astrophysical Observatory (BAO) will take place on 14-18 September 2026 in the National Academy of Sciences of the Republic of Armenia (NAS RA), Yerevan, Armenia. The Symposium is devoted to the role of BAO and its founder Viktor Ambartsumian in studies of non-stable phenomena and evolutionary processes in the Universe. Ambartsumian’s views and further BAO studies revolutionized our views on the evolution and dynamics of the Universe. Our perception and further investigation of the non-stable phenomena in the Universe is due to Ambartsumian’s efforts and contribution in science that is why the anniversary meeting is entitled “Our Non-Stable Universe”. BAO studies were mostly focused on the physics of nebulae, star systems, and extragalactic astronomy. Ambartsumian is best known for having discovered the Stellar Associations and predicted Activity of Galactic Nuclei, which became the most important topic of the extragalactic astronomy. He introduced important Statistical Methods to predict the total number of eruptive stars in stellar aggregates.

During the Symposium, an Astronomical Festival (AstroFest-2026) will be organized on 18 September (Viktor Ambartsumian’s birthday and also the official Astronomy Day in Armenia), where dozens of scientists, students and others will visit BAO and meet scientists, writers and poets, composers and artists. All registered participants will be invited to participate.

Byurakan Astrophysical Observatory (BAO) is one of the main observatories of the former Soviet Union and at present is an important observatory with modern facilities in the region. It was founded in 1946 by the outstanding Armenian scientist V. A. Ambartsumian (1908-1996) and is well known for its large spectroscopic surveys (FBS and SBS). BAO hosts a number of medium-size optical telescopes, the most important being the 2.6m classical telescope and 1m Schmidt telescope. BAO holds the Digitized First Byurakan Survey (DFBS, or the Digitized Markarian survey created in 2002-2007), containing low-dispersion spectra of ~20,000,000 objects and BAO Plate Archive, kind of astronomical heritage that are basis for modern technologies as well, namely the Armenian Virtual Observatory (ArVO), a member of the International Virtual Observatory Alliance (IVOA). DFBS has been included in 2011 in UNESCO “Memory of the World” documentary heritage International Register, one of the rarest scientific items in all UNESCO lists. BAO and Armenia host the IAU South West and Central Asian Regional Office of Astronomy for Development (SWCA ROAD) and support the development of astronomy in Armenia, Georgia, Iran, Kazakhstan, Tajikistan, Türkiye and other regional countries.

Armenian astronomy is also famous for a number of important astronomical meetings, organized by and mostly held in BAO: 7 IAU Symposia and Colloquia; IAU Symposia: #29 in 1966 (Non-Stable Phenomena in Galaxies), #121 in 1986 (Observational Evidence of Activity in Galaxies), #137 in 1989 (Flare Stars in Star Clusters, Associations and Solar Vicinity), #194 in 1998 (Activity in Galaxies and Related Phenomena), #304 in 2013 (Multiwavelength AGN Surveys and Studies) and #365 in 2023 (Dynamics of Solar and Stellar Convection Zones and Atmospheres), IAU Colloquium #184 in 2001 (AGN Surveys), as well as the European Annual Meeting JENAM was organized by BAO in Yerevan in 2007. The first international meeting on Communication with Extraterrestrial Intelligence (CETI) was organized in Byurakan in 1971. We have organized a UNESCO Conference “Astronomical Heritage of the Middle East” in 2017 and 2025. BAO-ESO Summer School was organized in 1987. The Byurakan International Summer Schools (BISS) are being organized since 2006, and 9 successful schools have been held in 2006, 2008, 2010 (combined with the 32th IAU ISYA), 2012, 2016, 2018, 2020, 2022 and 2024 (the 10BISS will be organized just before the BAO-80 Symposium, so that the students will also be able to attend). IAU SWCA Regional Astronomical Summer Schools (RASS) are being organized since 2019, and 4 such schools have been held in 2019, 2021, 2023 (the 1st Inter-Regional Astronomical Summer School, 1IRASS) and 2025. Many other meetings and schools have been organized as well, including those related to Non-Stable Phenomena, Flare Stars, Active Galaxies, Astronomical Surveys, Theoretical Astrophysics, Astronomical Instrumentation, Astronomical Heritage, History of Astronomy, Archaeoastronomy, Cultural Astronomy, Astronomical Education and Public Outreach.

Renowned scientists; astronomers, physicists, cosmologists and astronomy related interdisciplinary scientists will be invited to the meeting. We plan to have some 80 participants, including many young researchers and students.

The Meeting is also linked to the 10th Byurakan International Summer School (10BISS) to be held on 07-11 Sep 2026 in Byurakan, so that the participants of the School may attend both events, as well as some invited lecturers of the School may participate in the Symposium.