Picture of the Day: A Pulsar and Its Bright, Blue, Mysterious Tail

This composite image, made with data from NASA's Chandra X-ray Observatory (in blue) and data from the Digitized Sky Survey (in yellow), shows the pulsar known officially as PSR J0357+3205, or PSR J0357 for short. Astronomers recently discovered that the pulsar's spinning neutron center, which is at the upper-right quadrant of the image, has a long, bright X-ray tail. (The spherical blue object in the lower-left quadrant is believed to be unrelated, a background object outside of our galaxy, according to NASA. Same with the smaller blue streak just beneath it.)

"PSR J0357 was originally discovered by the Fermi Gamma Ray Space Telescope in 2009," according to NASA. "Astronomers calculate that the pulsar lies about 1,600 light years from Earth and is about half a million years old, which makes it roughly middle-aged for this type of objects."

View more Pictures of the Day.

Image: NASA.