Planetary science

General subfields within astronomy ...

See also:

Planetary science, Planetary science - Terminology, Planetary science - Basic Concepts

Read more here: » Planetary science: Encyclopedia II - Planetary science - Basic Concepts

A planet is generally considered to be a relatively large mass of accreted matter in orbit around a star that is not a star itself. The name comes from the Greek term πλανήτης, planētēs, meaning "wanderer", as ancient astronomers noted how certain lights moved across the sky in relation to the other stars. Based on historical consensus, the International Astronomical Union (IAU) lists nine planets in our solar system. Since the term "planet" has no precise scientific definition, however, many astronomers contest that ...

Including:

• Planet - Planetary formation
• Planet - Within our solar system
• Planet - Accepted planets
• Planet - Other candidates
• Planet - Extrasolar planets
• Planet - Brown dwarf planets
• Planet - Interstellar planets
• Planet - Definition and classification of planets
• Planet - Suggested wide definitions
• Planet - Suggested narrow definitions
• Planet - Further classification

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The 20th century brought more advances to study of the Moon. In 1946, scientists turned a radar dish to the Moon and for the first time received a return signal, thus enabling astronomers to use this new technology for things other than for military means. Telescopes became bigger and better, computers were beginning to be used, and rockets and missiles were being launched to study the upper atmosphere of the earth. Then in 1957, the Soviet Union launched Sputnik into orbit, beginning the race for space. The United States soo ...

See also:

Selenography, Selenography - Ancient History, Selenography - The Age of Discovery, Selenography - Ushering in the Space Age, Selenography - Lunar Anomalies, Selenography - Source, Selenography - Selenographers

Read more here: » Selenography: Encyclopedia II - Selenography - Ushering in the Space Age

An understanding of planetary habitability begins with stars, not planets themselves. While bodies that are generally Earth-like may be plentiful, it is just as important that their larger system be agreeable to life. Under the auspices of SETI's Project Phoenix, scientists Margaret Turnbull and Jill Tarter developed the "HabCat" (or Catalogue of Habitable Stellar Systems) in 2002. The catalogue was formed by winnowing the nearly 120,000 stars of the larger Hipparcos Catalogue into a core group of 17,000 "HabStars," and the selection criteri ...

See also:

Planetary habitability, Planetary habitability - Suitable star systems, Planetary habitability - Spectral class, Planetary habitability - A stable habitable zone, Planetary habitability - Low stellar variation, Planetary habitability - High metallicity, Planetary habitability - Binary systems, Planetary habitability - Planetary characteristics, Planetary habitability - Mass, Planetary habitability - Orbit and rotation, Planetary habitability - Geochemistry, Planetary habitability - Other considerations, Planetary habitability - The habitability of red dwarf planetary systems, Planetary habitability - Good Jupiters, Planetary habitability - The Galactic neighborhood, Planetary habitability - Notes

Read more here: » Planetary habitability: Encyclopedia II - Planetary habitability - Suitable star systems

The California Institute of Technology (commonly referred to as Caltech) is a private, coeducational university located in Pasadena, California, in the United States. One of the world's premier research universities, Caltech maintains a strong emphasis on the natural sciences and engineering. Caltech also owns and manages the Jet Propulsion Laboratory (JPL), an autonomous-space-flight complex that oversees the design and operation of most of NASA's space-probes. California Institute of Technology - History. Including:

• California Institute of Technology - History
• California Institute of Technology - Academics
• California Institute of Technology - Academic departments
• California Institute of Technology - Undergraduate program
• California Institute of Technology - Student life
• California Institute of Technology - House system
• California Institute of Technology - Traditions

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Much like "continent", "planet" is a word without a precise definition, with history and culture playing as much of a role as geology and astrophysics. Recent definitions have been vague and imprecise; The American Heritage Dictionary, for instance, formerly defined a planet as: A nonluminous celestial body larger than an asteroid or comet, illuminated by light from a star, such as the Sun, around which it revolves. In the solar system there are nine known planets: Mercury, Venus, Ea ...

See also:

Planet, Planet - Planetary formation, Planet - Within our solar system, Planet - Accepted planets, Planet - Other candidates, Planet - Extrasolar planets, Planet - Brown dwarf planets, Planet - Interstellar planets, Planet - Definition and classification of planets, Planet - Suggested wide definitions, Planet - Suggested narrow definitions, Planet - Further classification

Read more here: » Planet: Encyclopedia II - Planet - Definition and classification of planets

Axial tilt is an astronomical term regarding the inclination angle of a planet's rotational axis in relation to its orbital plane. It is also called axial inclination or obliquity. The axial tilt is expressed as the angle made by one half of the planet's axis and one half of a line drawn through the planet's center and perpendicular to the orbital plane, such that its rotation is in the same rotary direction relative to the former ...

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This is a list of academic disciplines (and academic fields). An academic discipline is a branch of knowledge which is formally taught, either at the university, or via some other such method. Functionally, disciplines are usually defined and recognised by the academic journals in which research is published, and the learned societies to which their practitioners belong. Each discipline usually has several sub-disciplines or branch ...

Including:

• List of academic disciplines - Natural sciences
• List of academic disciplines - Astronomy
• List of academic disciplines - Behavioral science
• List of academic disciplines - Biology
• List of academic disciplines - Chemistry
• List of academic disciplines - Physics
• List of academic disciplines - Earth sciences
• List of academic disciplines - Mathematics and computer science
• List of academic disciplines - Mathematics
• List of academic disciplines - Computer science
• List of academic disciplines - Social sciences
• List of academic disciplines - Anthropology
• List of academic disciplines - Archaeology
• List of academic disciplines - Communications
• List of academic disciplines - Economics
• List of academic disciplines - Ethnic Studies
• List of academic disciplines - Ethnology
• List of academic disciplines - History
• List of academic disciplines - Geography
• List of academic disciplines - Linguistics
• List of academic disciplines - Political science
• List of academic disciplines - Psychology
• List of academic disciplines - Semiotics
• List of academic disciplines - Sociology
• List of academic disciplines - Humanities and arts
• List of academic disciplines - Area studies sometimes called cultural studies
• List of academic disciplines - Art
• List of academic disciplines - Classics
• List of academic disciplines - Creative writing
• List of academic disciplines - Dance
• List of academic disciplines - English literature
• List of academic disciplines - Film studies and film criticism
• List of academic disciplines - Folklore
• List of academic disciplines - History
• List of academic disciplines - Linguistics
• List of academic disciplines - Literature and cultural studies
• List of academic disciplines - Music
• List of academic disciplines - Museology
• List of academic disciplines - Mythology
• List of academic disciplines - Philology
• List of academic disciplines - Philosophy
• List of academic disciplines - Religious studies
• List of academic disciplines - Theatre
• List of academic disciplines - Women's studies and gender studies
• List of academic disciplines - Professions / Applied sciences
• List of academic disciplines - Design
• List of academic disciplines - Business
• List of academic disciplines - Education
• List of academic disciplines - Engineering
• List of academic disciplines - Ergonomics
• List of academic disciplines - Agriculture
• List of academic disciplines - Forestry
• List of academic disciplines - Family and consumer science
• List of academic disciplines - Journalism and mass communications
• List of academic disciplines - Law
• List of academic disciplines - Library and information science
• List of academic disciplines - Health sciences
• List of academic disciplines - Military science
• List of academic disciplines - Public affairs and community service

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Science (from Latin scientia - knowledge) refers to a system of acquiring knowledge - based on empiricism, experimentation, and methodological naturalism - aimed at finding out the truth. The basic unit of knowledge is the theory, which is a hypothesis that is predictive. The term science also refers to the organized body of knowledge humans have gained by such research. Most scientists feel that scientific investigation must adhere to the scientific method, a process for evaluating empirical knowledge under the w ...

Including:

• Science - What is science?
• Science - Scientific method
• Science - Philosophy of science
• Science - Mathematics and the scientific method
• Science - Goals of science
• Science - Locations of science
• Science - Science and social concerns
• Science - Scientific literature
• Science - Fields of science
• Science - Natural sciences
• Science - Social sciences
• Science - Holistic interdisciplinary and applied sciences
• Science - Environmental sciences
• Science - Etymology
• Science - External articles and references
• Science - Textbooks
• Science - News and articles
• Science - Resources
• Science - Further reading

Read more here: » Science: Encyclopedia - Science

Theory has a number of distinct meanings in different fields of knowledge, depending on the context and their methodologies. Theory - Etymology. The word ‘theory’ derives from the Greek ‘theorein’, which means ‘to look at’. According to some sources, it was used frequently in terms of ‘looking at’ a theatre stage, which may explain why sometimes the word ‘theory’ is used as something provisional or not completely resembling real. The term ‘theoria’ (a noun) was already used by ...

Including:

• Theory - Etymology
• Theory - Science
• Theory - Models
• Theory - Types of theories
• Theory - Further explanation of a scientific theory
• Theory - Characteristics
• Theory - Mathematics
• Theory - Other fields
• Theory - List of famous theories
• Theory - Reference

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An albedo feature is a large area on the surface of a planet (or other solar system body) which shows a contrast in brightness or darkness (albedo) with adjacent areas. Historically, albedo features were the very first (and usually only) features to be seen and named on Mars and Mercury. Early classical maps (such as those of Schiaparelli and Antoniadi) showed only albedo features, and it was not until the arrival of space probes that other surface features like craters could be seen. On bodies other than Mars and Me ...

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Of the 173 extrasolar planets (those outside our solar system) discovered to date (October 2005) most have masses which are about the same or larger than Jupiter's. Exceptions include a number of planets discovered orbiting burned-out star remnants called pulsars, such as PSR B1257+12, the planets orbiting the stars Mu Arae, 55 Cancri and GJ 436 which are approximately Neptune-sized [1], and a planet orbiting Glies ...

See also:

Planet, Planet - Planetary formation, Planet - Within our solar system, Planet - Accepted planets, Planet - Other candidates, Planet - Extrasolar planets, Planet - Brown dwarf planets, Planet - Interstellar planets, Planet - Definition and classification of planets, Planet - Suggested wide definitions, Planet - Suggested narrow definitions, Planet - Further classification

Read more here: » Planet: Encyclopedia II - Planet - Extrasolar planets

The end of the 15th century was apparently when serious study of the Moon began. Around 1603, William Gilbert compiled the first lunar drawing based on naked-eye observations. Others soon followed, and when the telescope made its appearance on the scene, drawings were begun that at first were not very accurate, but soon became better as optics improved. In 1687, Isaac Newton stated that the Moon's motion was due to the forces of gravity. Other theories and discoveries were soon to come. In the early 1700s, the librations of the Moon w ...

See also:

Selenography, Selenography - Ancient History, Selenography - The Age of Discovery, Selenography - Ushering in the Space Age, Selenography - Lunar Anomalies, Selenography - Source, Selenography - Selenographers

Read more here: » Selenography: Encyclopedia II - Selenography - The Age of Discovery

At the beginning of recorded history, it was known that the passage of time could be determined by observing the positions and phases of the Moon. The idea that the Moon was not perfectly smooth can be traced as far back as approximately 450 BC, when Democritus believed that there were "lofty mountains and hollow valleys" on the Moon. Selenology (not be confused with selenography), which is the astronomical study of the Moon, began around the year 300 BC, when the Babylonian astronomers accumulated enough observational data about the ...

See also:

Selenography, Selenography - Ancient History, Selenography - The Age of Discovery, Selenography - Ushering in the Space Age, Selenography - Lunar Anomalies, Selenography - Source, Selenography - Selenographers

Read more here: » Selenography: Encyclopedia II - Selenography - Ancient History

Planetary habitability - The habitability of red dwarf planetary systems. Determining the habitability of red dwarf stars could help determine how common life in the universe is, as red dwarfs make up between 70 and 90 percent of all the stars in the galaxy. Brown dwarfs are likely more numerous than red dwarfs. However, they are not generally classified as stars, and could never support life as we unde ...

See also:

Planetary habitability, Planetary habitability - Suitable star systems, Planetary habitability - Spectral class, Planetary habitability - A stable habitable zone, Planetary habitability - Low stellar variation, Planetary habitability - High metallicity, Planetary habitability - Binary systems, Planetary habitability - Planetary characteristics, Planetary habitability - Mass, Planetary habitability - Orbit and rotation, Planetary habitability - Geochemistry, Planetary habitability - Other considerations, Planetary habitability - The habitability of red dwarf planetary systems, Planetary habitability - Good Jupiters, Planetary habitability - The Galactic neighborhood, Planetary habitability - Notes

Read more here: » Planetary habitability: Encyclopedia II - Planetary habitability - Other considerations

The chief assumption about habitable planets is that they be terrestrial. Such planets, roughly within one order of magnitude of Earth mass, are primarily composed of silicate rocks and have not accreted the gaseous outer layers of hydrogen and helium found on gas giants. That life could evolve in the cloud tops of giant planets has not been decisively ruled out 4, though it is considered unlikely given that they have no surface and their gravity is enormous See also:

Planetary habitability, Planetary habitability - Suitable star systems, Planetary habitability - Spectral class, Planetary habitability - A stable habitable zone, Planetary habitability - Low stellar variation, Planetary habitability - High metallicity, Planetary habitability - Binary systems, Planetary habitability - Planetary characteristics, Planetary habitability - Mass, Planetary habitability - Orbit and rotation, Planetary habitability - Geochemistry, Planetary habitability - Other considerations, Planetary habitability - The habitability of red dwarf planetary systems, Planetary habitability - Good Jupiters, Planetary habitability - The Galactic neighborhood, Planetary habitability - Notes

Read more here: » Planetary habitability: Encyclopedia II - Planetary habitability - Planetary characteristics

Main article: Solar system The process of naming planets and their features is known as planetary nomenclature. All the currently accepted planets in the solar system are named after Roman gods, except for Uranus (named after a Greek god) and the Earth, which was not seen as a planet by the ancients but rather the centre of the universe. The original number of planets was seven: Sun, Moon, Mercury, Venus, Mars, Jupiter, and Saturn. These were all seen as regular "wanderers" in the sky. Developments in Astronomy removed the Sun and the Moon, and added the current ...

See also:

Planet, Planet - Planetary formation, Planet - Within our solar system, Planet - Accepted planets, Planet - Other candidates, Planet - Extrasolar planets, Planet - Brown dwarf planets, Planet - Interstellar planets, Planet - Definition and classification of planets, Planet - Suggested wide definitions, Planet - Suggested narrow definitions, Planet - Further classification

Read more here: » Planet: Encyclopedia II - Planet - Within our solar system

Certain aspects of the Moon continue to baffle astronomers. It has been found that the full Moon, instead of having twice the illumination of the first or last quarter Moon, is in fact almost 19 percent brighter. Other mysteries concern lunar features that have apparently changed. One of the most famous cases concerns the lunar crater Linne in the are of Mare Serenitatis. In 1834, the German astronomer Lohrmann stated that the crater can be seen under all angles of illumination, and is the second most conspicuous crater on the Moon. T ...

See also:

Selenography, Selenography - Ancient History, Selenography - The Age of Discovery, Selenography - Ushering in the Space Age, Selenography - Lunar Anomalies, Selenography - Source, Selenography - Selenographers

Read more here: » Selenography: Encyclopedia II - Selenography - Lunar Anomalies

It is not known with certainty how planets are formed. The prevailing theory is that they are formed from those remnants of a nebula that don't condense under gravity to form a protostar. Instead, these remnants become a thin disc of dust and gas revolving around the protostar and begin to condense about local concentrations of mass within the disc. These concentrations become ever more dense until they collapse inward under gravity to form protoplanets. When the protostar has grown such that it ignites to form a star, its solar wind blows a ...

See also:

Planet, Planet - Planetary formation, Planet - Within our solar system, Planet - Accepted planets, Planet - Other candidates, Planet - Extrasolar planets, Planet - Brown dwarf planets, Planet - Interstellar planets, Planet - Definition and classification of planets, Planet - Suggested wide definitions, Planet - Suggested narrow definitions, Planet - Further classification

Read more here: » Planet: Encyclopedia II - Planet - Planetary formation

There are many different conceptions of the word "science". According to empiricism, scientific theories are objective, empirically testable, and predictive — they predict empirical results that can be checked and possibly contradicted. In contrast, scientific realism defines science in terms of ontology: science attempts to identify phenomena and entities in the environment, their causal powers, the mechanisms through which they exercise those powers, and the sources of those powers in terms ...

See also:

Science, Science - What is science?, Science - Scientific method, Science - Philosophy of science, Science - Mathematics and the scientific method, Science - Goals of science, Science - Locations of science, Science - Science and social concerns, Science - Scientific literature, Science - Fields of science, Science - Natural sciences, Science - Social sciences, Science - Holistic interdisciplinary and applied sciences, Science - Environmental sciences, Science - Etymology, Science - External articles and references, Science - Textbooks, Science - News and articles, Science - Resources, Science - Further reading

Read more here: » Science: Encyclopedia II - Science - What is science?