Joanna Rankin, University of Vermont (image) University of Vermont Caption Pulsars -- tiny spinning stars, heavier than the sun and smaller than a city -- have puzzled scientists since they were discovered in 1967. Now, new observations by an international team, including University of Vermont astrophysicist Joanna Rankin, make these bizarre stars even more puzzling. The scientists identified a pulsar that is able to dramatically change the way in which it shines. In just a few seconds, the star can quiet its radio waves while at the same time it makes its X-ray emissions much brighter. The research "challenges all proposed pulsar emission theories," the team writes in the Jan. 25, 2013, edition of the journal Science and reopens a decades-old debate about how these stars work. Credit Joshua Brown, University of Vermont Usage Restrictions None 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.