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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Vega in lyra.svg

Vega is the brightest star in the northern constellation of Lyra. It has the Bayer designation α Lyrae, which is Latinised to Alpha Lyrae and abbreviated Alpha Lyr or α Lyr. This star is relatively close at only 25 light-years (7.7 parsecs) from the Sun, and, together with Arcturus and Sirius, one of the most luminous stars in the Sun's neighborhood. It is the fifth-brightest star in the night sky, and the second-brightest star in the northern celestial hemisphere, after Arcturus.

Vega has been extensively studied by astronomers, leading it to be termed "arguably the next most important star in the sky after the Sun". Vega was the northern pole star around 12,000 BCE and will be so again around the year 13,727, when its declination will be +86° 14′. Vega was the first star other than the Sun to have its image and spectrum photographed. It was one of the first stars whose distance was estimated through parallax measurements. Vega has functioned as the baseline for calibrating the photometric brightness scale and was one of the stars used to define the zero point for the UBV photometric system. (Full article...)

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Double star Alpha Hercules.jpg
Credit: NVN271

Alpha Herculis is a multiple star system in the constellation of Hercules. A view of Alpha Herculis in a small telescope. The components A and B are resolved with angular separation of 4.64'' (in 2020).

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)

June anniversaries

Space-related Portals

Astronomical events

All times UT unless otherwise specified.

2 June, 01:14 Moon at apogee
14 June, 11:52 Full moon
14 June, 23:21 Moon at perigee
16 June, 14:59 Mercury at greatest western elongation
21 June, 09:14 Earth northern solstice
22 June, 18:16 Moon occults Mars
24 June, 22:13 Moon occults Uranus
29 June, 02:52 New moon
29 June, 06:08 Moon at apogee

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