[/caption] MESSENGER captured this high-resolution image of an elongated pit crater within the floor of the 355-km (220-mile) -wide crater Tolstoj on Mercury on Jan. 11, 2012. The low angle of sun illumination puts the interior of the pit crater into deep shadow, making it appear bottomless. Pit craters are not caused by impacts, but … Continue reading "A Peek at a Pitch-Black Pit"