Portal:Astronomy

The Astronomy Portal

Introduction

A man sitting on a chair mounted to a moving platform, staring through a large telescope.

Astronomy (from Greek: ἀστρονομία) 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, galaxies, 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 outside Earth's atmosphere. Cosmology is a branch of astronomy. It studies the Universe as a whole.

Astronomy is one of the oldest natural sciences. The early civilizations in recorded history made methodical observations of the night sky. These include the Babylonians, Greeks, Indians, Egyptians, Chinese, Maya, and many ancient indigenous peoples of the Americas. In the past, astronomy included disciplines as diverse as astrometry, celestial navigation, observational astronomy, and the making of calendars. Nowadays, professional astronomy is often said to be the same as astrophysics.

Professional astronomy is split into observational and theoretical branches. Observational astronomy is focused on acquiring data from observations of astronomical objects. This data is then analyzed using basic principles of physics. Theoretical astronomy is oriented toward the development of computer or analytical models to describe astronomical objects and phenomena. These two fields complement each other. Theoretical astronomy seeks to explain observational results and observations are used to confirm theoretical results.

Astronomy is one of the few sciences in which amateurs play an active role. This is especially true for the discovery and observation of transient events. Amateur astronomers have helped with many important discoveries, such as finding new comets.

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The Kreutz sungrazers (/ˈkrɔɪts/ (About this soundlisten), pronounced kroyts) are a family of sungrazing comets, characterized by orbits taking them extremely close to the Sun at perihelion. They are believed to be fragments of one large comet that broke up several centuries ago and are named for German astronomer Heinrich Kreutz, who first demonstrated that they were related. A Kreutz sungrazers's aphelion is about 170 AU from the Sun; these sungrazers make their way from the distant outer Solar System from a patch in the sky in Canis Major, to the inner Solar System, to their perihelion point near the Sun, and then leave the inner Solar System in their return trip to their aphelion.

Several members of the Kreutz family have become great comets, occasionally visible near the Sun in the daytime sky. The most recent of these was Comet Ikeya–Seki in 1965, which may have been one of the brightest comets in the last millennium. It has been suggested that another cluster of bright Kreutz system comets may begin to arrive in the inner Solar System in the next few years to decades. Read more...

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A color-composite image of the Pleiades from the Digitized Sky Survey
Credit: NASA/ESA/AURA/Caltech

In astronomy, the Pleiades, or Seven Sisters (Messier object 45), is an open star cluster containing middle-aged hot B-type stars located in the constellation of Taurus. It is among the nearest star clusters to Earth and is the cluster most obvious to the naked eye in the night sky.

Astronomy News

28 July 2020 –
Astronomers at Pan-STARRS announce the discovery of a small near-Earth object (NEO) HLV2514, which is an Amor asteroid near Mars. The asteroid was first discovered in June 2020 by two 14-year-old Indian schoolgirls who were participating in a NASA project. (CNN)
20 April 2020 –
New data from the Atacama Large Millimeter Array and Hubble Space Telescope, published in the Nature Astronomy journal, suggests interstellar comet 2I/Borisov contains large amounts of carbon monoxide and hydrogen cyanide. The new findings suggest the object was formed in the cold outer region of its planetary system. (BBC)
7 April 2020 –
Astronomers report, via The Astronomer's Telegram, that comet C/2019 Y4 (ATLAS) appears to have disintegrated. (The Independent)
13 March 2020 – Planets beyond Neptune
Astronomers discover 139 new "minor planets" in the Solar System that are beyond the orbit of Neptune, which helps boost odds of finding Planet Nine. (NBC News)
28 February 2020 –
A meteor explodes over Croatia. The Croatian Astronomical Union say the meteor disintegrated at an altitude of at least 30 kilometers above sea level. The meteor was likely roughly 2 meters across. (Xinhuanet) (The Dubrovnik Times) (JPL)
27 February 2020 –
Astronomers discover the largest known explosion ever in the history of the Universe, which occurred in the Ophiuchus galaxy cluster. It replaces MS 0735.6+7421. As space and ground telescopes that study radio emissions improve (which are better than X-ray observations for detecting these), more similar explosions, or "giant radio fossils", may be found. (Phys) (CNN) (Astrophysics via arXiv at Cornell University)

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