Snowball Earth (image) Harvard John A. Paulson School of Engineering and Applied Sciences Share Print E-Mail Caption About 700 million years ago, runaway glaciers covered the entire planet in ice. Harvard researchers modeled the conditions that may have led to this so-called 'snowball Earth'. Credit (Image courtesy of NASA) Usage Restrictions with credit 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.