An astronomer is a scientist in the field of astronomy who focuses their studies on a specific question or field outside the scope of Earth. They observe astronomical objects such as stars, planets, moons, comets, and galaxies – in either observational (by analyzing the data) 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. Related but distinct subjects like physical cosmology, which studies the Universe as a whole.

Astronomers usually fall under either of two main types: observational and theoretical. Observational astronomers make direct observations of celestial objects and analyze the data. In contrast, theoretical astronomers create and investigate models of things that cannot be observed. Because it takes millions to billions of years for a system of stars or a galaxy to complete a life cycle, astronomers must observe snapshots of different systems at unique points in their evolution to determine how they form, evolve, and die. They use these data to create models or simulations to theorize how different celestial objects work.

Further subcategories under these two main branches of astronomy include planetary astronomy, galactic astronomy, or physical cosmology.


Galileo is often referred to as the Father of modern astronomy

Historically, astronomy was more concerned with the classification and description of phenomena in the sky, while astrophysics attempted to explain these phenomena and the differences between them using physical laws. Today, that distinction has mostly disappeared and the terms "astronomer" and "astrophysicist" are interchangeable. Professional astronomers are highly educated individuals who typically have a Ph.D. in physics or astronomy and are employed by research institutions or universities.[1] They spend the majority of their time working on research, although they quite often have other duties such as teaching, building instruments, or aiding in the operation of an observatory.

The number of professional astronomers in the United States is actually quite small. The American Astronomical Society, which is the major organization of professional astronomers in North America, has approximately 7,000 members. This number includes scientists from other fields such as physics, geology, and engineering, whose research interests are closely related to astronomy.[2] The International Astronomical Union comprises almost 10,145 members from 70 different countries who are involved in astronomical research at the Ph.D. level and beyond.[3]

Br Guy in Lab
Guy Consolmagno Vatican Observatory, analyzing a meteorite, 2014

Contrary to the classical image of an old astronomer peering through a telescope through the dark hours of the night, it is far more common to use a charge-coupled device (CCD) camera to record a long, deep exposure, allowing a more sensitive image to be created because the light is added over time. Before CCDs, photographic plates were a common method of observation. Modern astronomers spend relatively little time at telescopes usually just a few weeks per year. Analysis of observed phenomena, along with making predictions as to the causes of what they observe, takes the majority of observational astronomers' time.

Astronomers who serve as faculty spend much of their time teaching undergraduate and graduate classes. Most universities also have outreach programs including public telescope time and sometimes planetariums as a public service to encourage interest in the field.

Those who become astronomers usually have a broad background in maths, sciences and computing in high school. Taking courses that teach how to research, write and present papers are also invaluable. In college/university most astronomers get a Ph.D. in astronomy or physics.

Amateur astronomers

Emily Lakdawalla at FameLab at LPSC 2013
Emily Lakdawalla at the Planetary Conference 2013

While there is a relatively low number of professional astronomers, the field is popular among amateurs. Most cities have amateur astronomy clubs that meet on a regular basis and often host star parties. The Astronomical Society of the Pacific is the largest general astronomical society in the world, comprising both professional and amateur astronomers as well as educators from 70 different nations.[4] Like any hobby, most people who think of themselves as amateur astronomers may devote a few hours a month to stargazing and reading the latest developments in research. However, amateurs span the range from so-called "armchair astronomers" to the very ambitious, who own science-grade telescopes and instruments with which they are able to make their own discoveries and assist professional astronomers in research.

See also



  1. ^ "Frequently Asked Questions About Becoming an Astronomer". NOAO. Archived from the original on 3 April 2009. Retrieved 29 March 2009.
  2. ^ "American Astronomical Society Home". AAS. Archived from the original on 2 August 2009. Retrieved 14 August 2009.
  3. ^ "About IAU". IAU. Retrieved 14 August 2009.
  4. ^ "About Us". Astronomical Society of the Pacific. Archived from the original on 25 February 2009. Retrieved 29 March 2009.


External links

Antonín Rükl

Antonín Rükl (September 22, 1932 – July 12, 2016) was a Czech astronomer, cartographer, and author.

He was born in Čáslav, Czechoslovakia. As a student he developed what was to be a lifelong interest in astronomy. He graduated from the Czech Technical University in 1956, then joined the staff of the astronomical department of the Institute of Geodesy in Prague.

In 1960 he joined the Prague Planetarium, eventually becoming deputy director and then head. He also became chairman of the Planetary Section of the Czechoslovak Astronomical Society and served as vice president of the International Planetarium Directors Conference from 1996 until 1999. He retired at the end of 1999.During his career he was a popularizer of astronomy and authored many books on the subject. He was skilled in cartography and selenography, the skill of mapping the Moon. He illustrated many of his own books, including the highly regarded Atlas of the Moon.He was married to Sonja. They had a daughter Jane and son Mike.

Astronomer Royal

Astronomer Royal is a senior post in the Royal Households of the United Kingdom. There are two officers, the senior being the Astronomer Royal dating from 22 June 1675; the second is the Astronomer Royal for Scotland dating from 1834.

The post was created by King Charles II in 1675, at the same time as he founded the Royal Observatory Greenwich. He appointed John Flamsteed, instructing him "forthwith to apply himself with the most exact care and diligence to the rectifying the tables of the motions of the heavens, and the places of the fixed stars, so as to find out the so-much desired longitude of places, for the perfecting the art of navigation."The Astronomer Royal was director of the Royal Observatory Greenwich from the establishment of the post in 1675 until 1972. The Astronomer Royal became an honorary title in 1972 without executive responsibilities and a separate post of Director of the Royal Greenwich Observatory was created to manage the institution.The Astronomer Royal today receives a stipend of 100 GBP per year and is a member of the Royal Household, under the general authority of the Lord Chamberlain. After the separation of the two offices, the position of Astronomer Royal has been largely honorary, though he remains available to advise the Sovereign on astronomical and related scientific matters, and the office is of great prestige.There was also formerly a Royal Astronomer of Ireland.

Ben Bussey

Ben J. Bussey is an American planetary scientist.

He earned a Ph.D. in planetary geology at University College London, England. In 2001, during his post-doctorate work at the University of Hawaii, he joined the ANSMET (Antarctic Search for METeorites) expedition to recover meteorites from the Antarctic glaciers. He worked at the Lunar and Planetary Institute in Houston and the European Space Agency, before joining the Johns Hopkins University Applied Physics Laboratory and becoming a senior staff scientist at that facility.

Bussey is specialized in the remote sensing of the surfaces of planets. He participated in the Near-Earth Asteroid Rendezvous-Shoemaker (NEAR) mission as a research scholar at Northwestern University, and co-authored an atlas of the Moon based on data and images from the Clementine mission. He has a particular interest in the lunar poles, using the Clementine images to locate crater cold traps for hydrogen deposits and mapping the peaks of eternal light.

He is married to Dr. Cari Corrigan.

James E. Gunn (astronomer)

James Edward Gunn (born October 21, 1938) is the Eugene Higgins Professor of Astronomy at Princeton University. Gunn's early theoretical work in astronomy has helped establish the current understanding of how galaxies form, and the properties of the space between galaxies. He also suggested important observational tests to confirm the presence of dark matter in galaxies, and predicted the existence of a Gunn–Peterson trough in the spectra of distant quasars.

Much of Gunn's later work has involved leadership in major observational projects. He developed plans for one of the first uses of digital camera technology for space observation, a project that led to the Sloan Digital Sky Survey, the most extensive three-dimensional mapping of the universe ever undertaken. He also played a major role with the Wide Field and Planetary Camera on the Hubble Space Telescope.

Gunn earned his bachelor's degree at Rice University in Houston, Texas, in 1961, and his Ph.D. from the California Institute of Technology (Caltech) in 1965. He joined the faculty of Princeton University two years later. Subsequently, he worked at the University of California at Berkeley and Caltech before returning to Princeton. He is married to the astronomer Gillian Knapp and they have two children, Humberto and Marleny Gunn.

List of minor planet discoverers

This is a list of all astronomers who are credited by the Minor Planet Center (MPC) with the discovery of one or several minor planets. A second table lists all institutional discoverers of minor planets such as observatories and surveys (see § Discovering dedicated institutions). As of October 2018, the MPC credits a total of 523,800 numbered minor planets to 1018 astronomers and 235 institutional discoverers (e.g. observatories, telescopes and surveys), respectively.

For how a discovery is made and a detailed description of the table, see observations of small Solar System bodies and § Notes, respectively.

List of pre-modern Iranian scientists and scholars

The following is a non-comprehensive list of Iranian scientists and engineers who lived from antiquity up until the beginning of the modern age. For the modern era, see List of contemporary Iranian scientists, scholars, and engineers. For mathematicians of any era, see List of Iranian mathematicians. (A person may appear on two lists, e.g. Abū Ja'far al-Khāzin.)

Liu Hong (astronomer)

Liu Hong (129–210), courtesy name Yuanzhuo, was a Chinese official, astronomer and mathematician who lived in the late Eastern Han dynasty. He developed a work on predicting the passage of the moon which was in use during the Three Kingdoms period of China.

Michael E. Brown

Michael E. Brown (born June 5, 1965) is an American astronomer, who has been professor of planetary astronomy at the California Institute of Technology (Caltech) since 2003. His team has discovered many trans-Neptunian objects (TNOs), notably the dwarf planet Eris, which was originally thought to be bigger than Pluto.He has been referred to by himself and by others as the man who "killed Pluto", because he furthered Pluto being downgraded to a dwarf planet in the aftermath of his discovery of Eris and several other probable trans-Neptunian dwarf planets. He is the author of How I Killed Pluto and Why It Had It Coming, published in 2010. He was awarded the Kavli Prize (shared with Jane X. Luu and David C. Jewitt) in 2012 “for discovering and characterizing the Kuiper Belt and its largest members, work that led to a major advance in the understanding of the history of our planetary system.”

Phil Plait

Philip Cary Plait (born September 30, 1964), also known as The Bad Astronomer, is an American astronomer, skeptic, writer and popular science blogger. Plait has worked as part of the Hubble Space Telescope team, images and spectra of astronomical objects, as well as engaging in public outreach advocacy for NASA missions. He has written two books, Bad Astronomy and Death from the Skies. He has also appeared in several science documentaries, including Phil Plait's Bad Universe and How the Universe Works on the Discovery Channel. From August 2008 through 2009, he served as president of the James Randi Educational Foundation. Additionally, he wrote and hosted episodes of Crash Course Astronomy, which aired its last episode in 2016.


Claudius Ptolemy (; Koine Greek: Κλαύδιος Πτολεμαῖος, Klaúdios Ptolemaîos [kláwdios ptolɛmɛ́os]; Latin: Claudius Ptolemaeus; c. AD 100 – c.  170) was a Greco-Roman mathematician, astronomer, geographer and astrologer. He lived in the city of Alexandria in the Roman province of Egypt, wrote in Koine Greek, and held Roman citizenship. The 14th-century astronomer Theodore Meliteniotes gave his birthplace as the prominent Greek city Ptolemais Hermiou (Greek: Πτολεμαΐς ‘Ερμείου) in the Thebaid (Greek: Θηβαΐδα [Θηβαΐς]). This attestation is quite late, however, and, according to Gerald Toomer, the translator of his Almagest into English, there is no reason to suppose he ever lived anywhere other than Alexandria. He died there around AD 168.Ptolemy wrote several scientific treatises, three of which were of importance to later Byzantine, Islamic and European science. The first is the astronomical treatise now known as the Almagest, although it was originally entitled the Mathematical Treatise (Μαθηματικὴ Σύνταξις, Mathēmatikē Syntaxis) and then known as the Great Treatise (Ἡ Μεγάλη Σύνταξις, Hē Megálē Syntaxis). The second is the Geography, which is a thorough discussion of the geographic knowledge of the Greco-Roman world. The third is the astrological treatise in which he attempted to adapt horoscopic astrology to the Aristotelian natural philosophy of his day. This is sometimes known as the Apotelesmatika (Ἀποτελεσματικά) but more commonly known as the Tetrabiblos from the Greek (Τετράβιβλος) meaning "Four Books" or by the Latin Quadripartitum.

Radio astronomy

Radio astronomy is a subfield of astronomy that studies celestial objects at radio frequencies. The first detection of radio waves from an astronomical object was in 1932, when Karl Jansky at Bell Telephone Laboratories observed radiation coming from the Milky Way. Subsequent observations have identified a number of different sources of radio emission. These include stars and galaxies, as well as entirely new classes of objects, such as radio galaxies, quasars, pulsars, and masers. The discovery of the cosmic microwave background radiation, regarded as evidence for the Big Bang theory, was made through radio astronomy.

Radio astronomy is conducted using large radio antennas referred to as radio telescopes, that are either used singularly, or with multiple linked telescopes utilizing the techniques of radio interferometry and aperture synthesis. The use of interferometry allows radio astronomy to achieve high angular resolution, as the resolving power of an interferometer is set by the distance between its components, rather than the size of its components.

Visible-light astronomy

Visible-light astronomy encompasses a wide variety of observations via telescopes that are sensitive in the range of visible light (optical telescopes). Visible-light astronomy is part of optical astronomy, and differs from astronomies based on invisible types of light in the electromagnetic radiation spectrum, such as radio waves, infrared waves, ultraviolet waves, X-ray waves and gamma-ray waves. Visible light ranges from 380 to 750 nanometers in wavelength.

Visible-light astronomy has existed as long as people have been looking up at the night sky, although it has since improved in its observational capabilities since the invention of the telescope, which is commonly credited to Hans Lippershey, a German-Dutch spectacle-maker, although Galileo played a large role in the development and creation of telescopes. Visible-light astronomy continues to advance in the modern day, with projects such as the James Webb Telescope being projected for launch in the next few years.

Since visible-light astronomy is restricted to only visible light, no equipment is necessary for simply star gazing. This means that it's the most commonly participated in type of astronomy, as well as the oldest.

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