The Universe within 500000 Light Years

The Universe within 500000 Light Years
The Satellite Galaxies

Number of large galaxies within 500 000 light years = 1

Number of dwarf galaxies within 500 000 light years = 12

Number of stars within 500 000 light years = 225 billion

About the Map

The Milky Way is surrounded by several dwarf galaxies, typically containing a few tens of millions of stars, which is insignificant compared with the number of stars in the Milky Way itself. This map shows the closest dwarf galaxies, they are all gravitationally bound to the Milky Way requiring billions of years to orbit it.

The Satellite Galaxies

Sagittarius Dwarf
	Lying on the far side of our galaxy this dwarf was discovered as recently as 1994. It is slowly being ripped apart by our galaxy.
Ursa Major II
	This galaxy was discovered in 2006. It is one of the smallest and faintest galaxies known, and it is too faint to appear on a normal photograph.
Large Magellanic Cloud
	The largest of the satellite galaxies and also the fourth largest galaxy in the Local Group. This galaxy is a large bright object in southern hemisphere skies and it is the brightest galaxy in the sky. It contains several billion stars and many stars are still forming in it, most notably in the Tarantula nebula, a huge concentration of gas and dust over 2000 light years in diameter. A supernova exploded in the Large Magellanic Cloud in 1987 and observations of the expanding supernova remnant provided accurate distance measurements to the galaxy.
Small Magellanic Cloud
	Despite its name, this galaxy is fairly large for a dwarf galaxy. It contains at least several hundred million stars and is easily visible with the naked eye from the southern hemisphere. Like the Large Magellanic Cloud, there is still a lot star formation taking place within it.
Boötes Dwarf
	This galaxy was discovered in 2006. It is one of the faintest galaxies ever discovered. It is too faint to appear on a normal photograph. It can be detected only by carefully counting the faint stars in this part of the sky.
Ursa Minor Dwarf
	Discovered in 1954, this is a very puny galaxy. Although it is a nearby galaxy it is far to dim to be seen with anything but a powerful telescope. All of the stars in this galaxy are at least ten billion years old, the galaxy is too small to allow it to hold on to gas and dust to allow any new star formation.
Sculptor Dwarf
	Discovered by Harlow Shapley in 1937. It is probably twice the size of the Ursa Minor galaxy, but all its stars seem to be just as old.
Draco Dwarf
	Discovered at the same time as the Ursa Minor dwarf galaxy in 1954, this galaxy is almost identical in size and consists of only very old stars.
Sextans Dwarf
	This galaxy was discovered in 1989. It is a very low luminosity galaxy but seems to be rather bigger than the Ursa Minor and Draco galaxies.
Ursa Major I
	This galaxy was discovered in 2005. It is another exceptionally faint galaxy rather like the Boötes Dwarf.
Carina Dwarf
	Discovered in 1977, this is another tiny dwarf galaxy. However most of its stars are slightly younger at about 7 billion years old than in most of the other tiny dwarf galaxies.
Fornax Dwarf
	Discovered at the same time as the Sculptor dwarf galaxy in 1937, it is several times larger than the smallest dwarf galaxies and contains several million stars. Its stars range in age from three to ten billion years old. This galaxy also has six globular clusters orbiting it.

Sagittarius Dwarf

Lying on the far side of our galaxy this dwarf was discovered as recently as 1994. It is slowly being ripped apart by our galaxy.

Ursa Major II

This galaxy was discovered in 2006. It is one of the smallest and faintest galaxies known, and it is too faint to appear on a normal photograph.

Large Magellanic Cloud

The largest of the satellite galaxies and also the fourth largest galaxy in the Local Group. This galaxy is a large bright object in southern hemisphere skies and it is the brightest galaxy in the sky. It contains several billion stars and many stars are still forming in it, most notably in the Tarantula nebula, a huge concentration of gas and dust over 2000 light years in diameter. A supernova exploded in the Large Magellanic Cloud in 1987 and observations of the expanding supernova remnant provided accurate distance measurements to the galaxy.

Small Magellanic Cloud

Despite its name, this galaxy is fairly large for a dwarf galaxy. It contains at least several hundred million stars and is easily visible with the naked eye from the southern hemisphere. Like the Large Magellanic Cloud, there is still a lot star formation taking place within it.

Boötes Dwarf

This galaxy was discovered in 2006. It is one of the faintest galaxies ever discovered. It is too faint to appear on a normal photograph. It can be detected only by carefully counting the faint stars in this part of the sky.

Ursa Minor Dwarf

Discovered in 1954, this is a very puny galaxy. Although it is a nearby galaxy it is far to dim to be seen with anything but a powerful telescope. All of the stars in this galaxy are at least ten billion years old, the galaxy is too small to allow it to hold on to gas and dust to allow any new star formation.

Sculptor Dwarf

Discovered by Harlow Shapley in 1937. It is probably twice the size of the Ursa Minor galaxy, but all its stars seem to be just as old.

Draco Dwarf

Discovered at the same time as the Ursa Minor dwarf galaxy in 1954, this galaxy is almost identical in size and consists of only very old stars.

Sextans Dwarf

This galaxy was discovered in 1989. It is a very low luminosity galaxy but seems to be rather bigger than the Ursa Minor and Draco galaxies.

Ursa Major I

This galaxy was discovered in 2005. It is another exceptionally faint galaxy rather like the Boötes Dwarf.

Carina Dwarf

Discovered in 1977, this is another tiny dwarf galaxy. However most of its stars are slightly younger at about 7 billion years old than in most of the other tiny dwarf galaxies.

Fornax Dwarf

Discovered at the same time as the Sculptor dwarf galaxy in 1937, it is several times larger than the smallest dwarf galaxies and contains several million stars. Its stars range in age from three to ten billion years old. This galaxy also has six globular clusters orbiting it.

The Universe within 500000 Light YearsThe Satellite Galaxies

About the Map

The Satellite Galaxies

The Universe within 500000 Light Years
The Satellite Galaxies