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Astronomy portal

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, Nubians, Iranians, 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.

Amateurs play an active role in astronomy. It is one of the few sciences in which this is the case. 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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Umbriel as seen by Voyager 2 in 1986
Umbriel /ˈʌmbriəl/ is a moon of Uranus discovered on October 24, 1851, by William Lassell. It was discovered at the same time as Ariel and named after a character in Alexander Pope's poem The Rape of the Lock. Umbriel consists mainly of ice with a substantial fraction of rock, and may be differentiated into a rocky core and an icy mantle. The surface is the darkest among Uranian moons, and appears to have been shaped primarily by impacts. However, the presence of canyons suggests early endogenic processes, and the moon may have undergone an early endogenically driven resurfacing event that obliterated its older surface.

Covered by numerous impact craters reaching 210 km (130 mi) in diameter, Umbriel is the second most heavily cratered satellite of Uranus after Oberon. The most prominent surface feature is a ring of bright material on the floor of Wunda crater. This moon, like all moons of Uranus, probably formed from an accretion disk that surrounded the planet just after its formation. The Uranian system has been studied up close only once, by the spacecraft Voyager 2 in January 1986. It took several images of Umbriel, which allowed mapping of about 40% of the moon’s surface.

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M82 HST ACS 2006-14-a-large web.jpg
Credit: NASA / ESA / Hubble Heritage Team (STScI/AURA)

Messier 82, also known as NGC 3034, Cigar Galaxy, and M82, is the prototype starburst galaxy about 12 million light-years away in the constellation Ursa Major. The starburst galaxy is five times more luminous than the whole Milky Way, and one hundred times more luminous than our galaxy's center. This mosaic image, taken by the Hubble Telescope, is the sharpest wide-angle view ever obtained of Messier 82.

Astronomy News

12 September 2019 – Interstellar objects
C/2019 Q4 (Borisov), a second interstellar comet after ʻOumuamua in 2017, is discovered by an amateur astronomer. (BBC)
19 August 2019 –
Astronomers led by a team from McGill University in Montreal announce the detection of eight new repeating fast radio bursts (FRBs) using the Canadian Hydrogen Intensity Mapping Experiment (CHIME) radio telescope. The astronomers report they also found complex morphologies and downward-drifting sub-bursts in some of the eight new FRBs. (Phys.org)
1 August 2019 – List of nearest exoplanets
Astronomers from the Max Planck Institute for Astronomy announce the discovery of red dwarf star GJ 357 and its three confirmed exoplanets in the Hydra constellation, one of which (GJ 357 d) is highly likely to be a super-Earth planet located in the system's circumstellar habitable zone where life can exist. The discovery was made using NASA's Transiting Exoplanet Survey Satellite (TESS). (The Independent)
17 July 2019 –
Astronomers rule out the chances of ~30-meter asteroid 2006 QV89's impacting Earth in September 2019 by eliminating the possibility of its passing through an area where it would have to be if it were on an impacting orbit. Prior to this, the asteroid had been given a one-in-7,000 chance of impacting Earth. (phys.org)
31 January 2019 –
Astronomers announce, through the Monthly Notices of the Royal Astronomical Society journal, the accidental discovery of dwarf spheroidal galaxy Bedin I in the Pavo constellation in September 2018. (Space Telescope)
17 December 2018 –
Astronomers announce the discovery of trans-Neptunian object 2018 VG18, the most distant object in the Solar System ever observed at a distance of ~120 AU. (Space.com)

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All times UT unless otherwise specified.

2 September, 10:42 Mars at conjunction
4 September, 01:42 Mercury at superior conjunction
8 September, 13:42 Moon occults Saturn
9 September, 03:05 Moon occults Pluto
10 September Neptune at opposition
13 September, 13:16 Moon at apogee
14 September, 04:33 Full moon
23 September, 07:50 Earth southward equinox
28 September, 02:17 Moon at perigee
28 September, 18:26 New moon

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