Galaxy

A galaxy is a system of stars, stellar remnants, interstellar gas, dust, dark matter, bound together by gravity. The word is derived from the Greek galaxias, literally 'milky', a reference to the Milky Way galaxy that contains the Solar System. Galaxies, averaging an estimated 100 million stars, range in size from dwarfs with less than a hundred million stars, to the largest galaxies known – supergiants with one hundred trillion stars, each orbiting its galaxy's center of mass. Most of the mass in a typical galaxy is in the form of dark matter, with only a few percent of that mass visible in the form of stars and nebulae. Supermassive black holes are a common feature at the centres of galaxies. Galaxies are categorized according to their visual morphology as elliptical, spiral, or irregular. Many are thought to have supermassive black holes at their centers. The Milky Way's central black hole, known as Sagittarius A, has a mass four million times greater than the Sun.

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Sound of The Big Bang Suggests Our Galaxy Floats Inside a Void

Dark dwarfs lurking at the center of our galaxy might hint at the nature of dark matter

Dark Dwarfs lurking at the center of our Galaxy might hint at the nature of dark matter - EurekAlert!

Dark Dwarfs lurking at the center of our Galaxy might hint at the nature of dark matter - EurekAlert!

Scientists spot mystery object believed to come from beyond solar system | Astronomer says object could be further evidence that ‘interstellar wanderers’ are common in galaxy

Astronomers discover a galaxy frozen in time for billions of years: 'Fossil galaxies are like the dinosaurs of the universe'

New Image Shows Andromeda Galaxy as We’ve Never Seen It Before

Astronomers capture the most intricate picture of a galaxy in a thousand colors ever seen

Nobel laureate concerned about AI-generated image of black hole at the center of our galaxy

Hubble Studies Small but Mighty Galaxy

Our Galaxy's Monster Black Hole Is Spinning Almost as Fast as Physics Allows

Astronomers capture most detailed thousand-color image of the Sculptor galaxy

A thousand colors, one galaxy: Astronomers reveal a cosmic masterpiece

Astronomers capture the most intricate picture of a galaxy in a thousand colors ever seen (photo, video)

Four new X-ray supernova remnants detected in the galaxy NGC 7793

Galaxy Clusters on Course to Crash Again, NASA’s Chandra Finds

Tiny Pebbles Created One of The Most Extreme Worlds in The Galaxy

Radio Wave- and X-Ray-Emitting Star is Unlike Anything Astronomers Have Seen in Our Galaxy

This Galaxy Is a Showstopper – But the Real Twist Is Nearby

Mysterious object spotted in our galaxy is emitting X-rays and radio waves, astronomers say