November 27, 1997
The universe does not repeat itself. Every sunrise is unique, every snowflake singular, and every birthday yours alone.
Jupiter's Inner Moons
Birthday · November 27, 1997
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APOD published November 27, 1997. Full image credits are on the original APOD entry below. A publication-date match, not a photo taken on your date. Independent of NASA.
The potato-shaped inner moons of Jupiter are lined-up in this mosaic "family portrait" of these tiny Jovian satellites. The individual images were recorded over the last year by NASA's Galileo spacecraft and are scaled to the moons' relative sizes. Left to right in increasing order of distance from Jupiter are Metis (longest dimension 37 miles), Adrastea (12 miles), Amalthea (154 miles), and Thebe (72 miles). All these moons orbit in the zone between Io and Jupiter's rings, are bombarded by high-energy ions within the Jovian magnetosphere, and are probably locked in synchronous rotation by Jupiter's strong gravity. Why are they shaped like potatoes? Like the asteroids and the diminutive moons of Mars, their own gravity is not strong enough to mold them into spheres.