[Jupiter's satellite Amalthea]
Photograph
[Jupiter's satellite Amalthea]
March 4, 1979
Chromogenic development print
Overall: 19 15/16 × 15 15/16 in. (50.7 × 40.5 cm)
Gift of NASA and NASA Jet Propulsion Laboratory
Inscriptions verso (applied label, typed): PUBLIC INFORMATION OFFICE/JET PROPULSION LABORATORY/CALIFORNIA INSTITUTE OF TECHNOLOGY/NATIONAL AERONAUTICS AND SPACE ADMINISTRATION/PASADENA, CALIFORNIA. TELEPHONE: (213) 354-5011/
PHOTO CAPTION Voyager 1-87/ P-21223C/ March 6, 1979/ Tiny, red Amalthea, Jupiter's innermost satellite whizzes around/ the planet every 12 hours, only 1.55 Jupiter radii from the cloud/ tops. In this view taken from a range of 255,000 miles (425,000/ kilometers) on March 4 by Voyager 1, the satellite appears about/ 80 miles (130 kilometers) high by 100 miles (170 kilometers) wide./ Since the phase angle is 29 1/4, part of the longer dimension is not/ illuminated. The terminator is on the right, north is at top,/ Jupiter is to the left. The reflectivity of the surface is less/ than 10%, making Amalthea much darker than the Galilean satellites./ Amalthea's irregular shape probably results from a long history/ of impact cratering. Some of the indentations near the bottom/ and at upper right may be marginally resolved craters. The/ effective resolution of this image is about 5 miles (8 kilometers)./ An important question is whether the red color is characteristic of/ the bulk of Amalthea, or whether, as is more likely, it results/ from a coating or alteration of the surface material. This irreg-/ular satellite probably keeps its long axis pointed toward Jupiter/ in its motions around the planet so that the spin period around its/ own axis equals its period of revolution around Jupiter (12 hours)./ Unlike the four large Galilean satellites which have been known/ since 1610, Amalthea was discovered only 87 years ago, in 1892, by/ the American astronomer Edmund Emerson Barnard at Lick Observatory./ JPL manages and controls the Voyager project for NASA's Office of/ Space Science.
PHOTO CAPTION Voyager 1-87/ P-21223C/ March 6, 1979/ Tiny, red Amalthea, Jupiter's innermost satellite whizzes around/ the planet every 12 hours, only 1.55 Jupiter radii from the cloud/ tops. In this view taken from a range of 255,000 miles (425,000/ kilometers) on March 4 by Voyager 1, the satellite appears about/ 80 miles (130 kilometers) high by 100 miles (170 kilometers) wide./ Since the phase angle is 29 1/4, part of the longer dimension is not/ illuminated. The terminator is on the right, north is at top,/ Jupiter is to the left. The reflectivity of the surface is less/ than 10%, making Amalthea much darker than the Galilean satellites./ Amalthea's irregular shape probably results from a long history/ of impact cratering. Some of the indentations near the bottom/ and at upper right may be marginally resolved craters. The/ effective resolution of this image is about 5 miles (8 kilometers)./ An important question is whether the red color is characteristic of/ the bulk of Amalthea, or whether, as is more likely, it results/ from a coating or alteration of the surface material. This irreg-/ular satellite probably keeps its long axis pointed toward Jupiter/ in its motions around the planet so that the spin period around its/ own axis equals its period of revolution around Jupiter (12 hours)./ Unlike the four large Galilean satellites which have been known/ since 1610, Amalthea was discovered only 87 years ago, in 1892, by/ the American astronomer Edmund Emerson Barnard at Lick Observatory./ JPL manages and controls the Voyager project for NASA's Office of/ Space Science.
