Portal:Astronomy

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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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Hubble Sees the Force Awakening in a Newborn Star (23807356641).jpg

Herbig–Haro (HH) objects are bright patches of nebulosity associated with newborn stars. They are formed when narrow jets of partially ionised gas ejected by stars collide with nearby clouds of gas and dust at several hundred kilometres per second. Herbig–Haro objects are commonly found in star-forming regions, and several are often seen around a single star, aligned with its rotational axis. Most of them lie within about one parsec (3.26 light-years) of the source, although some have been observed several parsecs away. HH objects are transient phenomena that last around a few tens of thousands of years. They can change visibly over timescales of a few years as they move rapidly away from their parent star into the gas clouds of interstellar space (the interstellar medium or ISM). Hubble Space Telescope observations have revealed the complex evolution of HH objects over the period of a few years, as parts of the nebula fade while others brighten as they collide with the clumpy material of the interstellar medium.

First observed in the late 19th century by Sherburne Wesley Burnham, Herbig–Haro objects were recognised as a distinct type of emission nebula in the 1940s. The first astronomers to study them in detail were George Herbig and Guillermo Haro, after whom they have been named. Herbig and Haro were working independently on studies of star formation when they first analysed the objects, and recognised that they were a by-product of the star formation process. Although HH objects are a visible wavelength phenomena, many remain invisible at these wavelengths due to dust and gas, and can only be detected at infrared wavelengths. Such objects, when observed in near infrared, are called molecular hydrogen emission-line objects (MHOs). (Full article...)

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Total Solar Eclipse 8-21-17.jpg
Credit: Michael S Adler

A total solar eclipse during totality, seen from outside Crowheart, Wyoming on 21 August, 2017. At this point during the solar eclipse, the photograph shows both the Sun's corona and the surface features of the new moon itself, illuminated by earthshine.

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)
4 April 2022 – Discoveries of exoplanets
Astronomers announce the discovery of K2-2016-BLG-0005Lb, an exoplanet that is said to resemble Jupiter. The discovery was made using the now-retired Kepler space telescope. (ScienceAlert)
30 March 2022 –
The Hubble Space Telescope observes the most distant single star ever. The star, named Earendel by astronomers, is 28 billion light-years away. It is the farthest detection of a star, dating back 900 million years after the Big Bang. This discovery surpasses Hubble's record from 2018, when it discovered a star that existed when the universe was roughly four billion years old. (CNN)

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Space-related Portals

Astronomical events

All times UT unless otherwise specified.

7 September, 18:17 Moon at perigee
10 September, 09:59 Full moon
14 September, 22:59 Moon occults Uranus
16 September, 21:03 Neptune at opposition
19 September, 14:44 Moon at apogee
23 September, 01:04 Earth southward equinox
23 September, 06:47 Mercury at inferior conjunction
25 September, 21:54 New moon
26 September, 18:03 Jupiter at opposition

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