Stickney Crater Is Nearly Half the Width of the Moon It Sits In

Stickney Crater is the largest crater on the Martian moon Phobos, and NASA's Astronomy Picture of the Day entry for October 9 gives a sense of the scale: over 9 kilometers across, it spans nearly half the diameter of Phobos itself. An impact that leaves a hole half the width of the body it hits is not a glancing blow — the explanation notes that the strike which blasted out Stickney likely came close to shattering the tiny moon altogether. Phobos is still there, which makes the crater less a scar than a near miss.