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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Jupiter's swirling clouds, in a true-color image taken by the Hubble Space Telescope in April 2017

The atmosphere of Jupiter is the largest planetary atmosphere in the Solar System. It is mostly made of molecular hydrogen and helium in roughly solar proportions; other chemical compounds are present only in small amounts and include methane, ammonia, hydrogen sulfide, and water. Although water is thought to reside deep in the atmosphere, its directly measured concentration is very low. The nitrogen, sulfur, and noble gas abundances in Jupiter's atmosphere exceed solar values by a factor of about three.

The atmosphere of Jupiter lacks a clear lower boundary and gradually transitions into the liquid interior of the planet. From lowest to highest, the atmospheric layers are the troposphere, stratosphere, thermosphere and exosphere. Each layer has characteristic temperature gradients. The lowest layer, the troposphere, has a complicated system of clouds and hazes, comprising layers of ammonia, ammonium hydrosulfide and water. The upper ammonia clouds visible at Jupiter's surface are organized in a dozen zonal bands parallel to the equator and are bounded by powerful zonal atmospheric flows (winds) known as jets. The bands alternate in color: the dark bands are called belts, while light ones are called zones. Zones, which are colder than belts, correspond to upwellings, while belts mark descending gas. The zones' lighter color is believed to result from ammonia ice; what gives the belts their darker colors is uncertain. The origins of the banded structure and jets are not well understood, though a "shallow model" and a "deep model" exist. (Full article...)

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Credit: NASA / ESA / STScI

HD 28527 is a star in the constellation Taurus, and a member of the Hyades open cluster. It is faintly visible to the naked eye with an apparent visual magnitude of 4.78. The distance to this star, as determined from its parallax shift of 22 mas, is 148 light years.

Astronomy News

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)
21 March 2022 – Discoveries of exoplanets
NASA announces that they have discovered their 5000th exoplanet since 1992, when astronomers Aleksander Wolszczan and Dale Frail announced the discovery of two exoplanets orbiting PSR B1257+12. (Science News)

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All times UT unless otherwise specified. Portal:Astronomy/Events/August 2022

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