The Solar System is the gravitationally bound system of the Sun and the masses that orbit it, most prominently its eight planets, of which Earth is one. The Solar System is an isolated single-star planetary system within the Milky Way Galaxy. The system formed about 4.6 billion years ago when a dense region of a molecular cloud collapsed, creating the Sun and a protoplanetary disc from which the orbiting bodies assembled.
Galaxy
A galaxy is a system of stars, stellar remnants, interstellar gas, dust, and dark matter bound together by gravity. The word is derived from the Greek galaxias (γαλαξίας), literally 'milky', a reference to the Milky Way galaxy that contains the Solar System. Galaxies, averaging an estimated 100 million stars, range in size from dwarfs with less than a thousand stars, to the largest galaxies known – supergiants with one hundred trillion stars, each orbiting its galaxy's centre of mass. Most of the mass in a typical galaxy is in the form of dark matter, with only a few percent of that mass visible in the form of stars and nebulae. Supermassive black holes are a common feature at the centres of galaxies.
Star
A star is a luminous spheroid of plasma held together by self-gravity. The nearest star to Earth is the Sun. Many other stars are visible to the naked eye at night; their immense distances from Earth make them appear as fixed points of light. The most prominent stars have been categorised into constellations and asterisms, and many of the brightest stars have proper names. Astronomers have assembled star catalogues that identify the known stars and provide standardized stellar designations. The observable universe contains an estimated 1022 to 1024 stars. Only about 4,000 of these stars are visible to the naked eye—all within the Milky Way galaxy.
Planetary Lexicon: Key Terms in Earth System Science
Define 90+ terms in planetary science — from Anthropocene and tipping points to planetary boundaries and the ecosphere.
Biosphere
The biosphere, also called the ecosphere, is the worldwide sum of all ecosystems. It can also be termed the zone of life on the Earth. The biosphere is virtually a closed system with regard to matter, with minimal inputs and outputs. Regarding energy, it is an open system, with photosynthesis capturing solar energy at a rate of around 100 terawatts. By the most general biophysiological definition, the biosphere is the global ecological system integrating all living beings and their relationships, including their interaction with the elements of the lithosphere, cryosphere, hydrosphere, and atmosphere. The biosphere is postulated to have evolved, beginning with a process of biopoiesis or biogenesis, at least some 3.5 billion years ago.
Planets and Bright Stars
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Cosmic dust
Cosmic dust – also called extraterrestrial dust, space dust, or star dust – is dust that occurs in outer space or has fallen onto Earth. Most cosmic dust particles measure between a few molecules and 0.1 mm (100 μm), such as micrometeoroids and meteoroids. Cosmic dust can be further distinguished by its astronomical location: intergalactic dust, interstellar dust, interplanetary dust, and circumplanetary dust. There are several methods to obtain space dust measurement.
The Cosmic Crash That Made the Moon
About 4.5 billion years ago, give or take, a planet the size of Mars slammed into the Earth. The Moon is what was left of the wreckage.
Compact object
In astronomy, the term compact object (or compact star) refers collectively to white dwarfs, neutron stars, and black holes. It could also include exotic stars if such hypothetical, dense bodies are confirmed to exist. All compact objects have a high mass relative to their radius, giving them a very high density compared to ordinary atomic matter. The term is used as a generalization for cases where the exact nature of a significant gravitational effect isolated to a small radius is not known.
Scareship Venus
The planet Venus normally sticks close to the Sun and so can only be seen very shortly after sunset, to the west (or before sunrise, to the east, when it is a morning star). But every 584 days, when it reaches maximum elongation in its orbit, it is far enough from the Sun in apparent [...]
A hierarchy of voids: Much ado about nothing
We present a model for the distribution of void sizes and its evolution in the context of hierarchical scenarios of gravitational structure formation. We find that at any cosmic epoch the voids...
The Coming Second Copernican Revolution | NOEMA
Astrobiology is rewiring our understanding of the intimate connection between life and planets as they appear in the universe.
Space Is the Place (Music From the Original Soundtrack), by Sun Ra & His Intergalactic Solar Arkestra
Social system
In sociology, a social system is the patterned network of relationships constituting a coherent whole that exist between individuals, groups, and institutions. It is the formal structure of role and status that can form in a small, stable group. An individual may belong to multiple social systems at once; examples of social systems include nuclear family units, communities, cities, nations, college campuses, religions, corporations, and industries. The organization and definition of groups within a social system depend on various shared properties such as location, socioeconomic status, race, religion, societal function, or other distinguishable features.
Store the season with Photoncycle
The year-round solar energy system for heating and electricity
Planetary Sapience & Planetary Stupidity: a Bildungsroman for the Baby Noosphere | Antikythera
That is, the faculty of recollection and foresight? Until recently, I would argue, our planet was amnesiac. That is, no part of it was reflectively aware of the place of the present relative to the established past nor the expected future. But then peculiar animals emerged, capable—no matter how imperfectly—of cooperation, abstraction and invention. In the last blink of geologic time, through the collaboration of these animals with their increasingly cunning artifacts, this state of planetary amnesia has faltering begun being cured. That is, through our artifacts, our planet is becoming aware of its own unfolding biography. In our fallible attempts to model our world—alongside our growing legion of sensors—The Earth system has developed a way of recollecting its deepest past and tracking the changing complexities of its present so as to forecast its furthest future.
