Extragalactic Astronomy

A branch of astronomy studying celestial bodies and systems that lie beyond our stellar system, the Milky Way galaxy. The formation of this branch of astronomy was preceded by a long period for determining what types of celestial bodies make up our stellar system and what types are found outside it.

The dawn of extragalactic astronomy was in 1917, when American astronomer Heber Curtis observed a stellar nova within M31, the formal name for what was then called the Great Andromeda Nebula. At the time, spiral nebulae such as Andromeda were thought to lie within our own galaxy, with a size only several times larger than that of our solar system and a distance less than 50,000 light-years.

Extragalactic Astronomy studies the structure and evolution of other galaxies, including their stellar populations, active galactic nuclei, and interstellar media, and the clustering of galaxies. Cosmology studies the structure and evolution of the universe as a whole.

The field of extragalactic astronomy extends from the Milky Way's nearest neighbors to distant galaxies observed less than a billion years after the big bang.

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Astronomers have for the first time spotted a planet that originated outside our galaxy.

The first alien planet from another galaxy has been detected, a new study suggests.

Any of the systems of stars and interstellar matter that make up the universe. Many such assemblages are so enormous that they contain hundreds of billions of stars.

An exoplanet orbiting a star that entered our Milky Way from another galaxy has been detected by a European team of astronomers using the MPG/ESO 2.2-metre telescope at ESO's La Silla Observatory in Chile. The Jupiter-like planet is particularly unusual, as it is orbiting a star nearing the end of its life and could be about to be engulfed by it, giving tantalising clues about the fate of our own planetary system in the distant future.

The SAAO is exploring a diverse range of topics in extragalactic astronomy.

ESO is the European Organisation for Astronomical Research in the Southern Hemisphere. It operates the La Silla Paranal Observatory in Chile and has its headquarters in Garching, near Munich, Germany.

An extragalactic planet, also known as an extragalactic exoplanet, is a planet that is outside the Milky Way. Due to the huge distance to those worlds, they are very hard to detect.

Extragalactic astronomy is the branch of astronomy concerned with objects outside the Milky Way galaxy. In other words, it is the study of all astronomical objects which are not covered by galactic astronomy, the next level of galactic astronomy.