Solar System
Rudi Albrecht
Space Telescope-European Coordinating Facility (ST-ECF)
"We conducted an intensive series of observations of Pluto with Hubble followed by advanced data processing on the ground. We saw surface features emerge for the first time in history on our screens. For me, personally, it was a memorable experience to be able to show this image to the original discoverer of Pluto, Clyde Tombaugh, and in this way let Hubble pay a tribute to his great discovery."
Hubble's high-resolution images of the planets and moons in our Solar System can only be surpassed by pictures taken from spacecraft that actually visit them. Furthermore Hubble can return to look at these objects periodically and so observe them over much longer periods (years) than any passing probe.
Regular monitoring of planetary surfaces is vital in the study of planetary atmospheres and geology, where evolving weather patterns such as dust storms can reveal much about the underlying processes. Hubble can also observe geological phenomena such as volcanic eruptions directly. The asteroid Vesta is only 500 km in diameter and was surveyed by Hubble from a distance of 250 million km. The resulting map of the surface shows a strange world with many lava flows, dominated by a gigantic impact crater.
Hubble is also able to react quickly to sudden dramatic events occurring in the Solar System. Most of the world kept an eye on Comet Shoemaker-Levy 9 when it made its fiery plunge into the atmosphere of the giant planet Jupiter during the period 16-22 July 1994. Hubble followed the comet fragments on their last journey and delivered stunning high-resolution images of the impact scars, from which important new information on conditions in the Jovian atmosphere was obtained.
On their fly-bys past Jupiter and Saturn the Voyager probes showed that these gas giants had aurorf similar to the northern lights here on Earth. However, Hubble's images of the aurorf were the first to reveal the delicate structure that so impressed many scientists. Hubble carries cameras that are sensitive to ultraviolet light, which is absorbed by the atmosphere and hence not seen by ground-based observatories.
Pluto is the only planet not yet visited by space probes, but in 1994 Hubble made the first clear images showing Pluto and its moon Charon as separate objects from a distance of 4.4 billion kilometres.
