NRAO/AUI/NSF, Arecibo

Venus is a shy planet that hangs out in the solar system, 25 million miles away from Earth. When seen from a ground telescope here, it looks like a clouded marble. The surface is hidden away under a thick coating of carbon-dioxide clouds.

It turns out Venus is hiding some dramatic surface features ranging from volcanoes to craters. A new image released by the National Radio Astronomy Observatory (NRAO) lifts the veil for a look at what lies beneath the clouds.

The image came about by combining the work of the National Science Foundation's Green Bank Telescope (a radio telescope in West Virginia) and the radar transmitter at the Arecibo Observatory in Puerto Rico.

The NRAO explains how it works: "The radar signals from Arecibo passed through both our planet's atmosphere and the atmosphere of Venus, where they hit the surface and bounced back to be received by the GBT in a process known as bistatic radar."

The result is an image showing mountains and craters. The dark line through the center highlights an area where it's difficult to collect good image data using this method. Scientists intend to compare images over time to look for active geologic processes on Venus.

"It is painstaking to compare radar images to search for evidence of change, but the work is ongoing. In the meantime, combining images from this and an earlier observing period is yielding a wealth of insight about other processes that alter the surface of Venus," said Bruce Campbell, senior scientist with the Center for Earth and Planetary Studies at the Smithsonian's National Air and Space Museum in Washington.

A paper based on the radar data work is scheduled for the April issue of the Icarus journal for solar system studies. The paper is titled "Evidence for crater ejecta on Venus tessera terrain from Earth-based radar images."