Astronomers used the National Science Foundation's (NSF) Green Bank Telescope (GBT) and the powerful radar transmitter at the NSF's Arecibo Observatory to take a detailed image of Venus. Radar signals passed through Earth's atmosphere and then through Venus' atmosphere which bounced the signals back to the GBT. The process is called "bistatic radar."
"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, D.C., according to a press release from the National Radio Astronomy Observatory (NRAO).
Comparisons of the 1988 and 2012 images of Venus are discussed in the journal Icarus.
