Michael Efroimsky () is an American

astronomer An astronomer is a scientist in the field of astronomy who focuses on a specific question or field outside the scope of Earth. Astronomers observe astronomical objects, such as stars, planets, natural satellite, moons, comets and galaxy, galax ...

of Russian origin. His research interests are in

celestial mechanics Celestial mechanics is the branch of astronomy that deals with the motions of objects in outer space. Historically, celestial mechanics applies principles of physics (classical mechanics) to astronomical objects, such as stars and planets, to ...

and

Planetary Science Planetary science (or more rarely, planetology) is the scientific study of planets (including Earth), celestial bodies (such as moons, asteroids, comets) and planetary systems (in particular those of the Solar System) and the processes of ...

. He is working as a Research Scientist at the US Naval Observatory in Washington DC. Michael Efroimsky is a member of the

International Astronomical Union The International Astronomical Union (IAU; , UAI) is an international non-governmental organization (INGO) with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach, education, and developmen ...

and the

American Astronomical Society The American Astronomical Society (AAS, sometimes spoken as "double-A-S") is an American society of professional astronomers and other interested individuals, headquartered in Washington, DC. The primary objective of the AAS is to promote the adv ...

(AAS). In 2008 - 2009, he served as the Chair of the Division on Dynamical Astronomy of the AAS. With Sergei Kopeikin and George Kaplan, Michael Efroimsky co-authored a book on the relativistic

of the

Solar System The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Sola ...

. With Benoit Noyelles, Julien Frouard and Valeri V. Makarov, Michael Efroimsky co-authored a theory explaining the origin of the present state of rotation of the planet Mercury, a so-called 3:2 spin-orbit resonance. With Amirhossein Bagheri, Amir Khan, and other colleagues, Michael Efroimsky co-authored a theory explaining the origin and orbital evolution of Phobos and Deimos, the satellites of

Mars Mars is the fourth planet from the Sun. It is also known as the "Red Planet", because of its orange-red appearance. Mars is a desert-like rocky planet with a tenuous carbon dioxide () atmosphere. At the average surface level the atmosph ...

. According to this theory, Phobos and Deimos are remnants of a common progenitor, a larger protomoon destroyed by a collision with a planetesimal. In 2024, Michael Efroimsky published a paper outlining the hypothesis to explain the unique shape of Mars. He suggested that the high triaxiality of this planet is due to a long-lost moon, which was synchronous, i.e., residing above the same point of the Martial equator. Efroimsky christened it Nerio. He demonstrated that if Nerio were large enough, perhaps a third the mass of the Moon, its gravitational pull on the young and still soft Mars was sufficient to create an asymmetric tidal bulge, which later fossilised and made the equator noncircular, resulting in the planet's triaxial shape. Efroimsky also hypothesised that the tips of that bulge were more prone to subsequent volcanic and tectonic activity than the rest of the Martian surface, leading to the development of both Tharsis and the highlands on the side opposite to it. Michael Efroimsky also published translations from classical Russian poetry.

Notes

External links

personal webpage
{{DEFAULTSORT:Efroimsky, Michael Year of birth missing (living people) Living people American astronomers