John Asher Johnson (4 January 1977) is an American astrophysicist and professor of

astronomy Astronomy () is a natural science that studies celestial objects and phenomena. It uses mathematics, physics, and chemistry in order to explain their origin and evolution. Objects of interest include planets, moons, stars, nebulae, g ...

at Harvard. He is the first tenured African-American physical science professor in the history of the university. Johnson is well known for discovering three of the first known planets smaller than the Earth outside of the solar system, including the first Mars-sized exoplanet.

Early life and education

Johnson grew up in

St. Louis St. Louis () is the second-largest city in Missouri, United States. It sits near the confluence of the Mississippi and the Missouri Rivers. In 2020, the city proper had a population of 301,578, while the bi-state metropolitan area, which e ...

. He graduated from the University of Missouri at Rolla (since renamed the Missouri University of Science and Technology) in 1999 with a Bachelors of Science degree in physics. In-between his undergraduate degree and graduate school, he also worked as a research scientist with

LIGO The Laser Interferometer Gravitational-Wave Observatory (LIGO) is a large-scale physics experiment and observatory designed to detect cosmic gravitational waves and to develop gravitational-wave observations as an astronomical tool. Two large ...

Caltech The California Institute of Technology (branded as Caltech or CIT)The university itself only spells its short form as "Caltech"; the institution considers other spellings such a"Cal Tech" and "CalTech" incorrect. The institute is also occasional ...

. He entered graduate school at

UC Berkeley The University of California, Berkeley (UC Berkeley, Berkeley, Cal, or California) is a public land-grant research university in Berkeley, California. Established in 1868 as the University of California, it is the state's first land-grant uni ...

having never taken a course in astronomy. Johnson completed his Ph.D. in astrophysics in 2007 under

Geoff Marcy Geoffrey William Marcy (born September 29, 1954) is an American astronomer. He was an early influence in the field of exoplanet detection, discovery, and characterization. Marcy was a professor of astronomy at the University of California, Berke ...

. His thesis was titled "Planet Hunting In New Stellar Domains" and included the detection of several unusual

hot Jupiters Hot Jupiters (sometimes called hot Saturns) are a class of gas giant exoplanets that are inferred to be physically similar to Jupiter but that have very short orbital periods (). The close proximity to their stars and high surface-atmosphere temp ...

Scientific career

Johnson is currently a professor of astronomy at Harvard, where he is one of several professors who study exoplanets along with

David Charbonneau David Brian Charbonneau is a professor of Astronomy at Harvard University. His research focuses on the development of novel techniques for the detection and characterization of exoplanets orbiting nearby, Sun-like stars. Early life and educat ...

, Dimitar Sasselov, and others. When he was appointed to this position in 2013, he became the first tenured African-American professor in any of the physical sciences at the university. He was formerly a professor at the

California Institute of Technology The California Institute of Technology (branded as Caltech or CIT)The university itself only spells its short form as "Caltech"; the institution considers other spellings such a"Cal Tech" and "CalTech" incorrect. The institute is also occasional ...

and a researcher with NASA's Exoplanet Science Research Institute. Before attaining a faculty job, Johnson was a

National Science Foundation The National Science Foundation (NSF) is an independent agency of the United States government that supports fundamental research and education in all the non-medical fields of science and engineering. Its medical counterpart is the National ...

(NSF) post-doctoral fellow at the Institute for Astronomy, a part of the

University of Hawaii A university () is an institution of higher (or tertiary) education and research which awards academic degrees in several academic disciplines. Universities typically offer both undergraduate and postgraduate programs. In the United States, th ...

Research

Johnson does research on the detection and characterization of

exoplanets An exoplanet or extrasolar planet is a planet outside the Solar System. The first possible evidence of an exoplanet was noted in 1917 but was not recognized as such. The first confirmation of detection occurred in 1992. A different planet, init ...

, that is, planets located outside the solar system. His work involves planets detected with a variety of methods. He is a founding principal investigator of the Miniature Exoplanet Radial Velocity Array (MINERVA), a ground-based robotic telescope array that searches for exoplanets primarily through the

radial velocity method Doppler spectroscopy (also known as the radial-velocity method, or colloquially, the wobble method) is an indirect method for finding extrasolar planets and brown dwarfs from radial-velocity measurements via observation of Doppler shifts in t ...

while also looking for transits. More related to transiting planets, Johnson has worked on precisely measuring the properties of planet-hosting stars found with the

Kepler mission The Kepler space telescope is a disused space telescope launched by NASA in 2009 to discover Earth-sized planets orbiting other stars. Named after astronomer Johannes Kepler, the spacecraft was launched into an Earth-trailing heliocentric orbi ...

, a vital task for determining the properties of the planets themselves. He is also involved with K2, the successor to the original Kepler mission. In 2012, Johnson's team discovered three small

rocky ''Rocky'' is a 1976 American sports drama film directed by John G. Avildsen and written by and starring Sylvester Stallone. It is the first installment in the ''Rocky'' franchise and stars Talia Shire, Burt Young, Carl Weathers, and Burge ...

in a red dwarf star system observed with the

Kepler space telescope The Kepler space telescope is a disused space telescope launched by NASA in 2009 to discover Earth-sized Exoplanet, planets orbiting other stars. Named after astronomer Johannes Kepler, the spacecraft was launched into an Earth-trailing heliocen ...

.Philip S. Muirhead, John Asher Johnson, Kevin Apps, Joshua A. Carter, Timothy D. Morton, Daniel C. Fabrycky, J. Sebastian Pineda, Michael Bottom, Barbara Rojas-Ayala, Everett Schlawin, Katherine Hamren, Kevin R. Covey, Justin R. Crepp, Keivan G. Stassun, Joshua Pepper, Leslie Hebb, Evan N. Kirby, Andrew W. Howard, Howard T. Isaacson, Geoffrey W. Marcy, David Levitan, Tanio Diaz-Santos, Lee Armus, James P. Lloyd, �
Characterizing the Cool KOIs III. KOI-961: A Small Star with Large Proper Motion and Three Small Planets
» published in ''The Astrophysical Journal'' – . The system was renamed

Kepler-42 Kepler-42, formerly known as KOI-961, is a red dwarf located in the constellation Cygnus and approximately 131 light years from the Sun. It has three known extrasolar planets, all of which are smaller than Earth in radius, and likely ...

and the outermost planet was found to be nearly as small as

Mars Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury. In the English language, Mars is named for the Roman god of war. Mars is a terrestrial planet with a thin at ...

, making it the smallest known exoplanet at the time. A subsequent study used the host star's similarity to

Barnard's Star Barnard's Star is a red dwarf about six light-years from Earth in the constellation of Ophiuchus. It is the fourth-nearest-known individual star to the Sun after the three components of the Alpha Centauri system, and the closest star in t ...

and observations from the

Keck Observatory The W. M. Keck Observatory is an astronomical observatory with two telescopes at an elevation of 4,145 meters (13,600 ft) near the summit of Mauna Kea in the U.S. state of Hawaii. Both telescopes have aperture primary mirrors, and when co ...

to more precisely measure the properties of the system, including the sizes of the three planets.

Diversity initiatives

Johnson is the founder of the Banneker Institute, a summer program hosted at the Center for Astrophysics Harvard & Smithsonian. The program provides research funding for undergraduate students from backgrounds underrepresented in astronomy, with a focus on students of color. It has merged with a similar program into the joint Banneker & Aztlán Institute, which also targets

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

and Native American students. In addition to research, the institute emphasizes discussions on social justice issues and their relevance in the field of astronomy.

References

External links

John Johnson's Research Group Page (The Johnson ExoLab at Harvard)

John Johnson's Personal Blog: Mahalo.ne.Trash

* {{DEFAULTSORT:Johnson, John 21st-century American astronomers Discoverers of exoplanets Living people People from Albuquerque, New Mexico Physicists from Missouri Scientists from St. Louis 1977 births 21st-century African-American scientists 20th-century African-American people