"We discovered a vertical hole on the moon," an international team of scientists recently announced.

The gaping, dark pit on the near side of the moon is as big as a city block and deep as a modest skyscraper. It is thought to be a collapsed lava tube, created perhaps billions of years ago when the moon was warmer and volcanically active.

The discovery, detailed in the journal Geophysical Research Letters in October, was made using data from the moon-orbiting Japanese SELENE spacecraft. It was not widely reported at the time, and the journal announced it today. The work was led by Junichi Haruyama of the Japanese Space Agency JAXA.