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, moons, comets and galaxies – in either observational or theoretical astronomy. Examples of topics or fields astronomers study include planetary science, solar astronomy, the origin or evolution of stars, or the formation of galaxies. A related but distinct subject is physical cosmology, which studies the Universe as a whole.
Astronomy is a natural science that studies celestial objects and the phenomena that occur in the cosmos. It uses mathematics, physics, and chemistry in order to explain their origin and their overall evolution. Objects of interest include planets, moons, stars, nebulae, galaxies, meteoroids, asteroids, and comets. Relevant phenomena include supernova explosions, gamma ray bursts, quasars, blazars, pulsars, and cosmic microwave background radiation. More generally, astronomy studies everything that originates beyond Earth's atmosphere. Cosmology is a branch of astronomy that studies the universe as a whole.
The American Astronomical Society 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 advancement of astronomy and closely related branches of science, while the secondary purpose includes enhancing astronomy education and providing a political voice for its members through lobbying and grassroots activities. Its current mission is to enhance and share humanity's scientific understanding of the universe as a diverse and inclusive astronomical community.
Astrophysics is a science that employs the methods and principles of physics and chemistry in the study of astronomical objects and phenomena. As one of the founders of the discipline, James Keeler, said, astrophysics "seeks to ascertain the nature of the heavenly bodies, rather than their positions or motions in space–what they are, rather than where they are", which is studied in celestial mechanics.
Vera Florence Cooper Rubin was an American astronomer who pioneered work on galaxy rotation rates. She uncovered the discrepancy between the predicted and observed angular motion of galaxies by studying galactic rotation curves. These results were later confirmed over subsequent decades. Her work on the galaxy rotation problem was cited by others as evidence for the existence of dark matter. The Vera C. Rubin Observatory in Chile is named in her honor.
Fritz Zwicky was a Swiss astronomer. He worked most of his life at the California Institute of Technology in the United States of America, where he made many important contributions in theoretical and observational astronomy. In 1933, Zwicky was the first to use the virial theorem to postulate the existence of unseen dark matter, describing it as "dunkle Materie".
Jeremiah Paul "Jerry" Ostriker is an American astrophysicist and a professor of astronomy at Columbia University and is the Charles A. Young Professor Emeritus at Princeton, where he also continues as a senior research scholar. Ostriker has also served as a university administrator as Provost of Princeton University.
Neil deGrasse Tyson is an American astrophysicist, author, and science communicator. Tyson studied at Harvard University, the University of Texas at Austin, and Columbia University. From 1991 to 1994, he was a postdoctoral research associate at Princeton University. In 1994, he joined the Hayden Planetarium as a staff scientist and the Princeton faculty as a visiting research scientist and lecturer. In 1996, he became director of the planetarium and oversaw its $210 million reconstruction project, which was completed in 2000. Since 1996, he has been the director of the Hayden Planetarium at the Rose Center for Earth and Space in New York City. The center is part of the American Museum of Natural History, where Tyson founded the Department of Astrophysics in 1997 and has been a research associate in the department since 2003.
Jay Myron Pasachoff was an American astronomer. Pasachoff was Field Memorial Professor of Astronomy at Williams College and the author of textbooks and tradebooks in astronomy, physics, mathematics, and other sciences.
John Peter Huchra was an American astronomer and professor. He was the Vice Provost for Research Policy at Harvard University and a Professor of Astronomy at the Center for Astrophysics | Harvard & Smithsonian. He was also a former chair of the United States National Committee for the International Astronomical Union. and past president of the American Astronomical Society.
Cosmos is a popular science book written by astronomer and Pulitzer Prize-winning author Carl Sagan. It was published in 1980 as a companion piece to the PBS mini-series Cosmos: A Personal Voyage with which it was co-developed and intended to complement. Each of the book's 13 illustrated chapters corresponds to one of the 13 episodes of the television series. Just a few of the ideas explored in Cosmos include the history and mutual development of science and civilization, the nature of the Universe, human and robotic space exploration, the inner workings of the cell and the DNA that controls it, and the dangers and future implications of nuclear war. One of Sagan's main purposes for both the book and the television series was to explain complex scientific ideas in a way that anyone interested in learning can understand. Sagan also believed the television was one of the greatest teaching tools ever invented, so he wished to capitalize on his chance to educate the world. Spurred in part by the popularity of the TV series, Cosmos spent 50 weeks on the Publishers Weekly best-sellers list and 70 weeks on the New York Times Best Seller list to become the best-selling science book ever published at the time. In 1981, it received the Hugo Award for Best Non-Fiction Book. The unprecedented success of Cosmos ushered in a dramatic increase in visibility for science-themed literature. The success of the book also served to jumpstart Sagan's literary career. The sequel to Cosmos is Pale Blue Dot: A Vision of the Human Future in Space (1994).
Amy J. Barger is an American astronomer and Henrietta Leavitt Professor of Astronomy at the University of Wisconsin–Madison. She is considered a pioneer in combining data from multiple telescopes to monitor multiple wavelengths and in discovering distant galaxies and supermassive black holes, which are outside of the visible spectrum. Barger is an active member of the International Astronomical Union.
Robert P. Kirshner is an American astronomer, Chief Program Officer for Science for the Gordon and Betty Moore Foundation, and the Clownes Research Professor of Science at Harvard University. Kirshner has worked in several areas of astronomy including the physics of supernovae, supernova remnants, the large-scale structure of the cosmos, and the use of supernovae to measure the expansion of the universe.
Alexei Vladimir "Alex" Filippenko is an American astrophysicist and professor of astronomy at the University of California, Berkeley. Filippenko graduated from Dos Pueblos High School in Goleta, California. He received a Bachelor of Arts in physics from the University of California, Santa Barbara in 1979 and a Ph.D. in astronomy from the California Institute of Technology in 1984, where he was a Hertz Foundation Fellow. He was a postdoctoral Miller Fellow at Berkeley from 1984 to 1986 and was appointed to Berkeley's faculty in 1986. In 1996 and 2005, he was a Miller Research Professor, and he is currently a Senior Miller Fellow. His research focuses on supernovae and active galaxies at optical, ultraviolet, and near-infrared wavelengths, as well as on black holes, gamma-ray bursts, and the expansion of the Universe.
Christopher John Lintott is a British astrophysicist, author and broadcaster. He is a Professor of Astrophysics in the Department of Physics at the University of Oxford, and, since 2023, Gresham Professor of Astronomy at Gresham College, London. Lintott is involved in a number of popular science projects aimed at bringing astronomy to a wider audience and is also the primary presenter of the BBC television series The Sky at Night, having previously been co-presenter with Patrick Moore until Moore's death in 2012. He co-authored Bang! – The Complete History of the Universe and The Cosmic Tourist with Moore and Queen guitarist and astrophysicist Brian May.
Andrew Fraknoi is a retired professor of astronomy recognized for his lifetime of work using everyday language to make astronomy more accessible and popular for both students and the general public. In 2017 Fraknoi retired from his position as Chair of the Department of Astronomy at Foothill College. In retirement he continues to teach through the Fromm Institute for Lifelong Learning and the Osher Lifelong Learning Institute at San Francisco State University, to give public lectures, and to add to his body of written work. He is the recipient of numerous awards and honors in his field.
Stephen P. Maran is an American astronomer and popularizer who is known for his books, articles, and popular lectures for the general public, including Astronomy For Dummies.
Christopher David Impey is a British astronomer, educator, and author. He has been a faculty member at the University of Arizona since 1986. Impey has done research on observational cosmology, in particular low surface brightness galaxies, the intergalactic medium, and surveys of active galaxies and quasars. As an educator, he has pioneered the use of instructional technology for teaching science to undergraduate non-science majors. He has written many technical articles and a series of popular science books including The Living Cosmos, How It Began, How It Ends: From You to the Universe, Dreams of Other Worlds, and Humble Before the Void. He served as Vice-President of the American Astronomical Society, he is a Fellow of the American Association for the Advancement of Science, and a Howard Hughes Medical Institute Professor. He serves on the Advisory Council of METI.
Ann Hornschemeier is an American astronomer specializing in X-ray emission from X-ray binary populations. She is the Chief Scientist for the Physics of the Cosmos program at NASA.
Matthew John O'Dowd is an Australian astrophysicist. He is an associate professor in the Physics and Astronomy Department at the Lehman College of the City University of New York and writer and host of PBS Space Time on YouTube. He is a frequent guest on Science Goes to the Movies on CUNY TV and on StarTalk radio with Neil deGrasse Tyson.
