How big is Sombrero Galaxy? | Scale of the Universe

The Sombrero Galaxy is a large galaxy in the constellation Virgo, about 31 million light-years from Earth. NASA and ESA give its width as about 50,000 light-years. A light-year is the distance light travels in one year, about 9.46 trillion kilometers. Seen almost edge-on, its bright, bulging center and dark lanes of dust make it look like a broad-brimmed hat, which gave it its name.

Size

ESA's description of the Hubble Space Telescope's images says the galaxy is 50,000 light-years across, and NASA's Chandra X-ray Center gives the same figure. Earth views the galaxy from 6 degrees above the plane of its disk, so it appears nearly edge-on.

Like every galaxy, the Sombrero has no sharp edge, and fainter light reaches much farther. Infrared images from the Spitzer Space Telescope show the disk wrapped in a much larger, roughly round cloud of old stars. The Updated Nearby Galaxy Catalog, which measures galaxies out to a very faint level of brightness, gives it a width of about 100,000 light-years. Hot gas seen in X-rays by Chandra reaches more than 60,000 light-years from the center.

The distance was measured in 2016 using Hubble. The brightest red giant stars in a galaxy all reach about the same true brightness, so how bright they look reveals how far away they are. By this method, the Sombrero is about 31 million light-years away. Earlier estimates ranged from about 20 million to 70 million light-years.

Size comparisons

The Sombrero Galaxy is about half the width of the Milky Way's disk, which is about 100,000 light-years across.
It is a little smaller than the Triangulum Galaxy, which is about 60,000 light-years across.
The Sombrero has about 2,000 globular clusters, dense groups of hundreds of thousands of old stars held together by gravity. That is about 10 times as many as the Milky Way has.
If the Sombrero Galaxy were shrunk to the size of a basketball, Earth would be about 150 meters (490 feet) away.

Spiral or elliptical

Astronomers first classified the Sombrero as a spiral galaxy with a very large central bulge, because of the disk of gas, dust and stars seen in ordinary light. The infrared view of a much larger, roughly round cloud of old stars led a 2012 study to classify it as an elliptical galaxy instead. That study proposed that the material forming the galaxy's disk was pulled in from outside the galaxy. The classification is still debated, and NASA's Hubble pages describe the Sombrero as a spiral.

In 2024, the James Webb Space Telescope photographed the galaxy in mid-infrared light, which shows dust. In that image, the glowing core seen in ordinary pictures does not shine, and the outer ring of dust shows clumps that may be places where new stars are forming. Even so, the Sombrero makes less than one Sun's mass of new stars each year, while the Milky Way makes about two.

A giant black hole

At the center of the Sombrero is a supermassive black hole with about 9 billion times the mass of the Sun. It pulls in material only slowly, and it sends out a small, bright jet. The whole galaxy has about 800 billion times the mass of the Sun, which makes it one of the most massive objects in the Virgo cluster of galaxies.

The French astronomer Pierre Méchain discovered the galaxy in 1781. It is too faint to see without a telescope, but a small telescope shows it, most easily in May. It is also known as Messier 104, or M104.