Tuesday, November 23, 2010

Sextet of Moons


Six of Saturn's moons orbiting within and beyond the planet's rings are collected in this Cassini spacecraft image.

Enceladus (504 kilometers, or 313 miles across) is the largest moon in this image and appears at the bottom. Janus (179 kilometers, or 111 miles across) orbits beyond the rings near the center of the image. Epimetheus (113 kilometers, or 70 miles across) orbits beyond the rings near the top of the image. Atlas (30 kilometers, or 19 miles across) appears as a tiny speck between the main rings and the thin F ring on the right. Daphnis (8 kilometers, or 5 miles across), which orbits in the narrow Keeler Gap of the A ring, appears as a small, bright speck on the left of the image. Pan (28 kilometers, or 17 miles across), which orbits in the Encke Gap of the A ring, also appears as a bright speck on the left of the image. Daphnis is farther to the left of the image than Pan.

Although Enceladus appears to be in the foreground here, that moon, at a distance of 3.1 million kilometers (1.9 million miles), is actually farthest away from Cassini in this image. Janus is 3 million kilometers (1.9 million miles) from the spacecraft. The view was obtained at a distance of approximately 2.8 million kilometers (1.7 million miles) from Epimetheus.

The rings lie between Janus and Epimetheus. This view looks toward the southern, unilluminated side of the rings from about 2 degrees below the ringplane.

Enceladus is a very reflective body. To enhance visibility, the other moons and the rings have been brightened by a factor of 3.4 relative to Enceladus.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on October 6, 2010. Image scale is approximately 19 kilometers (12 miles) per pixel on Enceladus, about 18 kilometers (11 miles) per pixel on Janus and about 17 kilometers (11 miles) per pixel on Epimetheus.

Photo credit: NASA/JPL/Space Science Institute

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