A Texas-sized dust storm swirled around the Martian north pole for months, as shown in these images taken by the Hubble Space Telescope Sept. 18 and Oct. 15, 1996, and released by NASA Nov. 4. The storm is about 600 miles across and was probably a result of large temperature differences between polar ice and the dark regions to the south, which are heated by the springtime sun. Scientists believe it to be the first time that one of Mars' famous dust storms has been located near the receding north polar ice cap. The presence of water on Mars, even in polar ice, is significant to the inquiry on whether life might have existed on the planet.