Outline of Galaxies: A Cosmic Journey Through Stellar Systems

Welcome to our cosmic tour of galaxies! These fascinating systems are gravitationally bound conglomerates of stars, stellar remnants, interstellar gas, dust, and dark matter. The term “galaxy” derives from the Greek word ‘galaxias’, meaning ‘milky’, a nod to the Milky Way we call home.

Key Points about Galaxies

• Galaxies can vary significantly in size, ranging from dwarfs with a few billion stars to giants boasting over one hundred trillion.
• Each galaxy has a center of mass around which its celestial bodies orbit.
• Galaxies are categorized based on their visual morphology: elliptical, spiral, and irregular.
• Many galaxies are believed to harbor supermassive black holes at their centers.

The Milky Way and Beyond

The Milky Way’s central black hole, known as Sagittarius A*, is four million times more massive than our Sun. While we call it home, the Milky Way isn’t the most distant or oldest galaxy ever observed. As of March 2016, GN-z11 holds that title, with a comoving distance of approximately 32 billion light-years from Earth. This means we are observing it as it existed just 400 million years after the Big Bang.

Before GN-z11, the most distant known galaxy was EGSY8p7, estimated to be about 13.2 billion light-years away.