Richard Conn Henry (born 7 March 1940) is an Academy Professor of Physics and Astronomy at

Johns Hopkins University Johns Hopkins University (Johns Hopkins, Hopkins, or JHU) is a private university, private research university in Baltimore, Maryland. Founded in 1876, Johns Hopkins is the oldest research university in the United States and in the western hem ...

, author of one book and over 200 publications on the topics of astrophysics and various forms of astronomy including optical, radio, ultraviolet, and X-ray. He reports being part of a team that discovered "vastly more

baryon In particle physics, a baryon is a type of composite subatomic particle which contains an odd number of valence quarks (at least 3). Baryons belong to the hadron family of particles; hadrons are composed of quarks. Baryons are also classified ...

s than had ever before been found in the universe". He is also cited in the effort to recategorize Pluto as a dwarf planet. He initially joined the Johns Hopkins University Physics Department in 1968 as the first JHU astronomer since 1908. After a stint at NASA, he returned to help attract in 1981 the

Space Telescope Science Institute The Space Telescope Science Institute (STScI) is the science operations center for the Hubble Space Telescope (HST), science operations and mission operations center for the James Webb Space Telescope (JWST), and science operations center for th ...

to JHU, an organization that now employs 500, including 100 PhDs. More recently he has attracted popular press for the SETI ecliptic search idea and the Hanke-Henry Permanent Calendar. The SETI ecliptic search idea suggests focusing SETI efforts in the ecliptic plane in which distant hypothetical observers can see the Earth's transit of the sun. The Hanke-Henry Permanent Calendar is one in which the number of days in a year is always divisible by seven, such that holidays always fall on the same day of the week. Most years have only four quarters of 91 days, while every five or six years an extra week is inserted at the end of December. He is also active in various organizations, including the

Streit Council The Streit Council for a Union of Democracies is Washington, DC-based 501(c)(3) nonprofit foreign policy think tank working to unite democracies as a path toward greater individual freedom, international solidarity, and global stability. It aims ...

, where as of 2012 he is president; the Maryland Space Grant Consortium; and an organization he founded, the Henry Foundation, which "sponsors improved worldwide understanding of physics". He earned a Ph.D. from

Princeton University Princeton University is a private university, private research university in Princeton, New Jersey. Founded in 1746 in Elizabeth, New Jersey, Elizabeth as the College of New Jersey, Princeton is the List of Colonial Colleges, fourth-oldest ins ...

in 1967. He is cited for providing, for black holes that are rotating, and/or are electrically charged, the

Kretschmann scalar In the theory of Lorentzian manifolds, particularly in the context of applications to general relativity, the Kretschmann scalar is a quadratic scalar invariant. It was introduced by Erich Kretschmann. Definition The Kretschmann invariant is : ...

, which characterizes their degree of curvature.

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Further reading