While Hubble cannot see as fine a detail as the Mars Global Surveyor, which its currently in orbit around Mars, it can obtain a better global picture. The telescope obtained several images showing the entire planet. Each view depicts one quarter of its daily rotation. The images were taken in the middle of the Martian northern summer, when the northern polar cap had shrunk to its smallest size because the Sun shines continuously on the polar cap. The images show that substantial changes in the bright and dark markings on Mars have taken place in the 20 years since the NASA Viking spacecraft missions first mapped the planet.
Martian winds blow sand and dust from region to region, often in spectacular dust storms.
Small details come and go as they are covered and then uncovered by sand and dust.