The Astronomy Portal

Introduction

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

Astronomy (from Ancient Greek ἀστρονομία (astronomía) 'science that studies the laws of the stars') 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 beyond Earth's atmosphere. Cosmology is a branch of astronomy that 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. (Full article...)

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The scheme of Uranus's ring-moon system. Solid lines denote rings; dashed lines denote orbits of moons.
The scheme of Uranus's ring-moon system. Solid lines denote rings; dashed lines denote orbits of moons.

The rings of Uranus are intermediate in complexity between the more extensive set around Saturn and the simpler systems around Jupiter and Neptune. The rings of Uranus were discovered on March 10, 1977, by James L. Elliot, Edward W. Dunham, and Jessica Mink. William Herschel had also reported observing rings in 1789; modern astronomers are divided on whether he could have seen them, as they are very dark and faint.

By 1977, nine distinct rings were identified. Two additional rings were discovered in 1986 in images taken by the Voyager 2 spacecraft, and two outer rings were found in 2003–2005 in Hubble Space Telescope photos. In the order of increasing distance from the planet the 13 known rings are designated 1986U2R/ζ, 6, 5, 4, α, β, η, γ, δ, λ, ε, ν and μ. Their radii range from about 38,000 km for the 1986U2R/ζ ring to about 98,000 km for the μ ring. Additional faint dust bands and incomplete arcs may exist between the main rings. The rings are extremely dark—the Bond albedo of the rings' particles does not exceed 2%. They are probably composed of water ice with the addition of some dark radiation-processed organics. (Full article...)

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PIA18848-PSRB1509-58-ChandraXRay-WiseIR-20141023.jpg
Credit: NASA / CXC / SAO (X-Ray) / NASA/JPL-Caltech (Infrared)

PSR B1509−58 is a pulsar approximately 17,000 light-years away in the constellation of Circinus discovered by the Einstein X-Ray Observatory in 1982. X-rays from Chandra are gold; infrared from WISE in red, green and blue/max.

Astronomy News

9 August 2022 – Discoveries of exoplanets
Radio astronomers have discovered a newborn, Jupiter-size exoplanet orbiting the star AS 209, using the Atacama Large Millimeter Array telescope in Chile. (Space.com)
26 April 2022 –
In the morning, the Moon, Jupiter, and Venus are seen aligning with each other. (Space.com)

October anniversaries

Space-related Portals

Astronomical events

All times UT unless otherwise specified.

4 October, 17:01 Moon at perigee
8 October, 20:59 Mercury at greatest western elongation
9 October, 20:55 Full moon
12 October, 06:46 Moon occults Uranus
17 October, 10:21 Moon at apogee
21 October, 17:39 Orionids peak
22 October, 20:47 Venus at superior conjunction
24 October, 15:44 Moon occults Mercury
25 October, 11:00 New moon and partial solar eclipse
25 October, 12:05 Moon occults Venus
29 October, 14:48 Moon at perigee

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