H. Jay Melosh (June 23, 1947 – September 11, 2020) was an American

geophysicist Geophysics () is a subject of natural science concerned with the physical processes and properties of Earth and its surrounding space environment, and the use of quantitative methods for their analysis. Geophysicists conduct investigations acros ...

specialising in

impact crater An impact crater is a depression (geology), depression in the surface of a solid astronomical body formed by the hypervelocity impact event, impact of a smaller object. In contrast to volcanic craters, which result from explosion or internal c ...

ing. He earned a degree in physics from

Princeton University Princeton University is a private university, private Ivy League research university in Princeton, New Jersey, United States. Founded in 1746 in Elizabeth, New Jersey, Elizabeth as the College of New Jersey, Princeton is the List of Colonial ...

and a doctoral degree in physics and geology from

Caltech The California Institute of Technology (branded as Caltech) is a private university, private research university in Pasadena, California, United States. The university is responsible for many modern scientific advancements and is among a small g ...

in 1972. His PhD thesis concerned quarks. Melosh's research interests include

impact craters An impact crater is a depression in the surface of a solid astronomical body formed by the hypervelocity impact of a smaller object. In contrast to volcanic craters, which result from explosion or internal collapse, impact craters typically ...

, planetary tectonics, and the physics of

earthquakes An earthquakealso called a quake, tremor, or tembloris the shaking of the Earth's surface resulting from a sudden release of energy in the lithosphere that creates seismic waves. Earthquakes can range in intensity, from those so weak they c ...

and

landslides Landslides, also known as landslips, rockslips or rockslides, are several forms of mass wasting that may include a wide range of ground movements, such as rockfalls, mudflows, shallow or deep-seated slope failures and debris flows. Landslide ...

. His recent research includes studies of the giant impact origin of the Moon, the

Chicxulub impact The Chicxulub crater is an impact crater buried underneath the Yucatán Peninsula in Mexico. Its center is offshore, but the crater is named after the onshore community of Chicxulub Pueblo (not the larger coastal town of Chicxulub Puerto). I ...

that is thought to have extinguished most

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic Geological period, period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the #Evolutio ...

s, and studies of ejection of rocks from their parent bodies. He was active in

astrobiological Astrobiology (also xenology or exobiology) is a scientific field within the List of life sciences, life and environmental sciences that studies the abiogenesis, origins, Protocell, early evolution, distribution, and future of life in the univ ...

studies that relate chiefly to the exchange of

microorganisms A microorganism, or microbe, is an organism of microscopic size, which may exist in its single-celled form or as a colony of cells. The possible existence of unseen microbial life was suspected from antiquity, with an early attestation in ...

between the terrestrial planets (a process known as

panspermia Panspermia () is the hypothesis that life exists throughout the universe, distributed by space dust, meteoroids, asteroids, comets, and planetoids, as well as by spacecraft carrying unintended contamination by microorganisms,Forward planetary c ...

or transpermia). Melosh was a member of the

American Geophysical Union The American Geophysical Union (AGU) is a 501(c)(3) nonprofit organization of Earth, Atmospheric science, atmospheric, Oceanography, ocean, Hydrology, hydrologic, Astronomy, space, and Planetary science, planetary scientists and enthusiasts that ...

Geological Society of America The Geological Society of America (GSA) is a nonprofit organization dedicated to the advancement of the geosciences. History The society was founded in Ithaca, New York, in 1888 by Alexander Winchell, John J. Stevenson, Charles H. Hi ...

Meteoritical Society The Meteoritical Society is a non-profit scholarly organization founded in 1933 to promote research and education in planetary science with emphasis on studies of meteorites and other extraterrestrial materials that further our understanding of th ...

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 ...

(Division of Planetary Sciences,) and the

American Association for the Advancement of Science The American Association for the Advancement of Science (AAAS) is a United States–based international nonprofit with the stated mission of promoting cooperation among scientists, defending scientific freedom, encouraging scientific responsib ...

. He was the recipient of the Barringer Medal of the

for his work on the physics of impact, and of the

G. K. Gilbert Award The G. K. Gilbert Award is presented annually by the Planetary Geology Division of the Geological Society of America for outstanding contributions to the solution of fundamental problems in planetary geology in the broadest sense, which includes ge ...

from the

. He was elected to the

National Academy of Sciences The National Academy of Sciences (NAS) is a United States nonprofit, NGO, non-governmental organization. NAS is part of the National Academies of Sciences, Engineering, and Medicine, along with the National Academy of Engineering (NAE) and the ...

in 2003.

Career

H. Jay Melosh took his first faculty role at

between 1976 and 1979, where he researched the Moon's orientation in relation to mass concentrations ( mascons) and large impacts, and was also a member of the

GRAIL The Holy Grail (, , , ) is a treasure that serves as an important motif in Arthurian literature. Various traditions describe the Holy Grail as a cup, dish, or stone with miraculous healing powers, sometimes providing eternal youth or sustenanc ...

science team. He then went on to take a position with

SUNY Stonybrook Stony Brook University (SBU), officially the State University of New York at Stony Brook, is a public research university in Stony Brook, New York, United States, on Long Island. Along with the University at Buffalo, it is one of the State Univ ...

as an associate professor of geophysics until 1982 when he left to join the

University of Arizona The University of Arizona (Arizona, U of A, UArizona, or UA) is a Public university, public Land-grant university, land-grant research university in Tucson, Arizona, United States. Founded in 1885 by the 13th Arizona Territorial Legislature, it ...

as a faculty member in the planetary sciences, where he continued work on impact cratering until 2009. In 2009, Dr. Melosh moved to the

Purdue University Purdue University is a Public university#United States, public Land-grant university, land-grant research university in West Lafayette, Indiana, United States, and the flagship campus of the Purdue University system. The university was founded ...

Department of Earth, Atmospheric, and Planetary Sciences to study impact cratering,

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 ...

, and geophysics until his retirement.

Awards and honors

* Asteroid 8216 Melosh is named in his honor. * The American Geophysical Union 2008 Harry H. Hess Medal - for “outstanding achievements in research in the constitution and evolution of Earth and sister planets.” * In 2024 Melosh Crater was named after him in his honor. The crater is located near the Aram Chaos terrain in the equatorial region of Mars. The crater is almost 100 km in diameter and has a history of lava infilling and water flooding.

Publications

* * ''Planetary Surface Processes'',

Cambridge University Press Cambridge University Press was the university press of the University of Cambridge. Granted a letters patent by King Henry VIII in 1534, it was the oldest university press in the world. Cambridge University Press merged with Cambridge Assessme ...

, 2011, ()

References

External links

Homepage of H. Jay Melosh
{{DEFAULTSORT:Melosh, H. Jay American geophysicists Members of the United States National Academy of Sciences 1947 births 2020 deaths American planetary scientists American Astronomical Society Writers from Paterson, New Jersey Scientists from New Jersey Barringer Medal winners