Ulysses was a spacecraft designed to look at the sun as well as the regions above and below the sun's poles. To get there, however, the spacecraft took a bit of a circuitous route. It lifted off into space on NASA's space shuttle Discovery on Oct. 6, 1990. From there, it was released from the cargo bay and flew out towards Jupiter to get a planned gravity assist up and over the sun's poles.
More than a year later, on Feb. 8, 1992, Ulysses came within about 446,000 kilometers (277,000 miles) of Jupiter. There it found some dust, with a frequency of about once a month,
. The dust was believed to either come from Jupiter itself or its volcanic moon, Io. But it also found different dust -- bigger particles moving opposite to how the planets move. This was the first time that dust particles from beyond our solar system were detected.
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Image: Artist's impression of Ulysses and Comet Hyakutake, which whizzed into the inner solar system in 1996.