A new Hubble Space Telescope image released Thursday, May 11 reveals a pair of galaxies, perfectly overlapped to create a beautiful silhouette of dust in the foreground galaxy. Astronomers who discovered the pair say the image is extremely interesting because the luminous background galaxy highlights dust in the foreground galaxy that would otherwise be hidden by the black background of space.

The two galaxies, known as NGC 3314-A and NGC 3314-B, lie close to 140 million light-years away from Earth, in the constellation Hydra. The pair was imaged in April, 1999 by William Keel and Ray White III, University of Alabama astronomers who were actually searching the skies for overlapping galaxies in order to settle a little score.

The Hubble Space Telescope captured this image of galaxies NGC 3314-A (foreground) and NGC 3314-B (background). The image will enable scientists to study dust in the foreground galaxy.

"Quite a controversy had erupted as to whether theres so much dust in galaxies that it completely blocks our view and we dont see even half of whats there, or whether theres a lot less," said Keel. "So we decided to start looking for pairs of overlapping galaxies [to find out]. We went through every galaxy catalog we could find, and we found about a dozen pairs that were big enough to learn something from."

Of the dozen galaxy pairs, Keel and White were able to image three in detail with the Hubble Space Telescope. As it turns out, the overlap between the foreground and background galaxies in NCG 3314 is the most exact ever seen. This exactness has allowed astronomers to measure the amount of dust there is near the center of the foreground galaxy, a feat that is normally impossible to accomplish with solo galaxies due to the black background of space behind them.

The dust of the foreground galaxy, NGC 3314-A, is easily visible to astronomers because it absorbs light emanating from the background galaxy, which lies somewhere between 15 million and 25 million light-years behind NGC 3314-A. "You can see this very red splotch, which is the light from the center of the background galaxy filtering through this huge amount of dust on the way," said Keel. "It turns out that only about 1 percent of the blue light makes it through."

"We desperately hope theres nothing special about [these two] galaxies," added Keel. Thats because he hopes to someday use observations about the dust in NGC 3314-A to describe galaxies the universe over.

But before that can happen, more research in the way of overlapping galaxies must be done. Yet already, some of Keel and Whites observations about this particular pair have proved quite valuable. "Already, weve shown that the dust in the backlit galaxy is very similar to the dust in our galaxy," said Keel.