Astronomical event

An astronomical event is a more or less rarely occurring event that has its cause outside the earth . Examples are: bright comets , rare eclipses or planetary encounters, small planets close to the earth, supernovae in neighboring galaxies or extraordinary phenomena in the earth's atmosphere .

In contrast, the umbrella term celestial appearance is used for phenomena visible to the naked eye in the sky , such as the rising and setting of bright stars, twilight effects, atmospheric halos , planetary loops and conjunctions, star coverings , variable stars and the like. You will be in the article

→ A closer look at astronomical phenomenology .

overview

Most astronomical events relate to objects in the solar system , or to those in which one of the bodies involved is part of the solar system. Astronomical events that do not originate from bodies in the solar system are mostly due to unusual changes in stars .

Astronomical events also refer to rare phenomena within the earth's atmosphere , such as light phenomena, electromagnetic effects or larger meteors that hit the earth from space or previously burn up as fireballs .

Events in astronomy also include some that cannot be observed in the visible spectrum ( visual astronomy ) (e.g. gamma-ray flashes ) or, in a broader sense, those that take too long to be perceived as an event for humans ( in extreme cases about a galaxy penetration over many millions of years).

However, many of these astronomical events cannot be predicted because of their unexpected occurrence.

Predictable events

• Rises and sets as well as culminations of the heavenly bodies
• Twilight times , white nights , polar day and night
• Conjunctions between the sun , moon , planets or asteroids with each other or with fixed stars , and other aspects
• Transits ( passages , coverings ): occultations of stars (especially by the moon , rarely by planets or asteroids), transits of planets from the sun ( Mercury and Venus transits )
• Solar and lunar eclipses ,
• The appearance of periodic comets and their conjunctions with other celestial bodies
• Passage of the apses and nodes of planets, moon, asteroids or periodic comets
• Brightness maxima and brightness minima of periodic variable stars
• Double star passages and the movement of exoplanets
• In space travel also rocket launches , orbit maneuvers or rendezvous

Predictable astronomical events are usually listed in astronomical yearbooks and published 1–2 years in advance.

Conditionally predictable events

• Close encounters and impacts on earth, especially from the orbits of objects close to the earth : the very rare larger bodies over about 50 meters have been increasingly cataloged and monitored since about 2005. Smaller meteorites and their previous luminous phenomena ( shooting stars and fireballs ) , however, are hardly predictable . The detection of large objects near the earth is considered to be one of the pressing problems of modern observational astronomy
• Meteor shower (periodic accumulation of falling stars) - time frame easily predictable, intensity only approximated
• Appearances of the earth's atmosphere , the immediate causes of which lie outside of it
• The collision of the Milky Way with the Andromeda Galaxy , as this will only take place in a few billion years.
• Maxima and minima of semi-regularly changing stars
• Photometeors (light phenomena):
  • Zodiacal Light , Luminous Night Clouds , Halo and Glory , and more
• Electrometeors (electromagnetic caused optical phenomena), whichare basedon solar storms and their consequences, also these are at the limit of today's predictability (with the SOHO probe can be warned at least a few minutes in advance):
  • Northern lights , Cherenkov lightning

Unpredictable events

• Show non-periodic comet (about 20 to 30 per year)
• Novae and supernovae
• Bursts (Gamma Ray Bursts)
• Gravitational wave / star collision
• Shooting stars (small meteors)
• Any extraterrestrial signals such as those sought by the SETI project
• Events that have never happened before and that have not yet followed any theory that we do not know.

literature

• Wolfgang Held: Solar and lunar eclipses - and the most important astronomical constellations up to 2017 . Free Spiritual Life Publishing House, Stuttgart 2005, ISBN 3-7725-2231-9
• Hermann Mucke: Modern astronomical phenomenology . Sternfreunde Seminar 1992/93, Austria. Astronomical Association, Vienna 1992

Web links

Commons : Astronomical Events  - collection of images, videos and audio files

• The most important celestial events from 2001 to 2020. In: himmelsereignisse.info