How Many Galaxies Are There?

QUICK ANSWER

Current estimates put the number of galaxies in the observable universe at 2 trillion or more. Each galaxy contains anywhere from a few million to hundreds of billions of stars. The total number is uncertain because we can't see every galaxy directly, and new telescopes keep finding more.

The observable universe contains at least 2 trillion galaxies, based on the best current estimates. Each galaxy can contain millions to hundreds of billions of stars. The number keeps growing as telescopes get more powerful and find more galaxies that were previously too faint to detect. The total may eventually be revised significantly upward.

How many galaxies are there in the universe?

At least 2 trillion in the observable universe. According to NASA, the 2-trillion estimate comes from a 2016 analysis using Hubble Space Telescope deep-field observations. The number is much higher than the 100-200 billion previously estimated, because deep observations revealed many faint, small galaxies that earlier surveys missed. The James Webb Space Telescope is finding even more galaxies in the early universe, suggesting the actual number could be higher still.

How big can galaxies get?

Hundreds of billions of stars in the biggest cases. Our Milky Way has 100-400 billion stars and is considered a large galaxy. Some galaxies are vastly bigger: IC 1101 may contain over 100 trillion stars and span millions of light years across. Smaller galaxies (dwarf galaxies) might have only a few million stars. The range of galaxy sizes is enormous, with most galaxies actually being smaller than the Milky Way. Dwarf galaxies are by far the most common type.

How are galaxies organized?

In groups and clusters. Galaxies aren't distributed randomly in space. They cluster into groups (a few galaxies) and clusters (dozens to thousands), with even larger structures called superclusters and filaments connecting them. The cosmic web is the name for the largest-scale structure, with galaxies arranged along vast filaments separated by enormous voids. The Milky Way is part of the Local Group of about 50 galaxies, which is itself part of the Virgo Supercluster, which is part of the Laniakea Supercluster.

Are new galaxies being discovered?

Constantly. The James Webb Space Telescope, launched in 2021, has revealed galaxies in the very early universe that earlier telescopes couldn't see. Some of these galaxies are surprisingly large and mature for their early age, challenging existing models of galaxy formation. As telescopes improve, more galaxies are found. The total number of galaxies isn't likely to be pinned down precisely anytime soon, but estimates will continue refining as our observations improve.

The observable universe contains at least 2 trillion galaxies, each with millions to hundreds of billions of stars. The number keeps growing as telescopes find fainter, more distant galaxies. Galaxies aren't randomly distributed but organized into clusters and superclusters connected by filaments in the cosmic web. The James Webb Space Telescope is continuing to revise our understanding of how many galaxies actually exist.

How Many Galaxies Are There?