Transit Method (IMAGE) Penn State Caption Earth-bound astronomers use the transit method--measuring the dim in a star's light when a planet passes directly between the star and its observer--to study planets outside of the Solar System. A new study looks for signals of extraterrestrial civilizations that may be using the transit method to study the Earth. Credit NASA's Jet Propulsion Laboratory Usage Restrictions Credit must be provide alongside image. License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.