The observatory phase, originally scheduled to start on December 15, 1978, eighty days before encounter, was postponed until January 4, 1979, to provide the flight team a holiday-season break. For the next two months, Voyager would carry out a long-term scientific study—a “time history”—of Jupiter, its satellites, and its magnetosphere. On January 6, Voyager 1 began photographing Jupiter every two hours—each time taking a series of four photographs through different color filters as part of a long-duration study of large-scale atmospheric processes, so scientists could study the changing cloud patterns on Jupiter. Even the first of these pictures showed that the atmosphere was dynamic “with more convective structure than had previously been thought.” Particularly striking were the changes in the planet, especially near the Great Red Spot, that had taken place since the Pioneer flybys in 1973 and 1974. Jupiter was wearing a new face for Voyager. In mid-January, photos of Jupiter were already being praised for “showing exceptional details of the planet’s multicolored bands of clouds.” Still 47 million kilometers from the giant, Voyager 1 had by now taken more than 500 photographs of Jupiter. Movements of cloud patterns were becoming more obvious; feathery structures seemed painted across some of the bands that encircle the planet; swirling features were huddled near the Great Red Spot. The satellites were also beginning to look more like worlds, with a few bright spots visible on Ganymede and dark red poles and a bright equatorial region clearly seen on Io when it passed once each orbit across the turbulent face of Jupiter. From January 30 to February 3, Voyager sent back one photograph of Jupiter every 96 seconds over a 100-hour period. Using a total of three different color filters, the spacecraft thus produced one color picture every 4¾ minutes, in order to make a “movie” covering ten Jovian “days.” To receive these pictures, sent back over the high-rate X-band transmitter, the Deep Space Network’s 64-meter antennas provided round-the-clock coverage. Voyager 1 was ready for its far encounter phase. [Illustration: The Galilean satellites of Jupiter first began to show as tiny worlds, not mere points of light, as the Voyager 1 observatory phase began. In this view taken January 17, 1979, at a range of 47 million kilometers, the differing sizes and surface reflectivities (albedos) of Ganymede (right center) and Europa (top right) are clearly visible. The view of Jupiter is unusual in that the Great Red Spot is not easily visible, but can just be seen at the right edge of the planet. Most pictures selected for publication include the photogenic Red Spot. [P-20938C]] Far Encounter Phase