A Tenth Planet? (image) University of Arizona Share Print E-Mail Caption A planetary mass object the size of Mars would be sufficient to produce the observed perturbations in the distant Kuiper Belt. Credit Heather Roper/LPL Usage Restrictions This visual may only be used in conjunction of reporting/posting of this news release. Credit must be stated as indicated. Share Print E-Mail 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.