Dwarf galaxy's sudden arrival near Milky Way surprises researchers

An entire dwarf galaxy has caught astronomers by surprise, appearing in orbit around the Milky Way when, last they looked, it hadn't been there. Called the Crater 2 dwarf galaxy, this 'new' Milky Way neighbor was recently detailed by researchers in a new study, and is said to be the fourth largest dwarf galaxy in the Milky Way. How did it avoid detection for so long? Among other things, its stars are spread far apart, making it dim and 'ghostly' in nature.

The Crater 2 dwarf galaxy was discovered by the University of Cambridge's Gabriel Torrealba and fellow researchers, and it lies approximately 380,000 light years away. Overall, the galaxy can't be seen with the human eye, showing just how dim it is. Thanks to modern technology, though, the researchers were able to spot it using a computer to analyze photos snapped by a large telescope located in Chile.

Were we able to see the galaxy with the naked eye, it would be about double the size of a full moon. As well, the galaxy is said to be rounded in shape, meaning the Milky Way is the first big galaxy it has come across — if it had happened across a different one at some point in its past, the gravity from the larger galaxy would have changed the dwarf galaxy's shape.

The Crater 2 dwarf galaxy is, of course, only one of many dwarf galaxies orbiting our own. Its discovery has inspired astronomers to keep an eye out for other very dim galaxies, though, and word has it there may already be some other previously unknown galaxies in the nearby vicinity with the same ghostly appearance.

VIA: New Scientist