(CNN) -- NASA's New Horizons explorer is hurtling through space on its way to the outermost reaches of the solar system for a rendezvous with the small, icy "dwarf planet" of Pluto and its five moons. It's a staggering decade-long, 3 billion mile journey that started with the New Horizons launch in 2006. The space probe is expected to reach Pluto next summer, the only spacecraft to visit it. It's also only the fifth probe to ever journey so far from the sun across such vast reaches of space, according to NASA officials. New Horizons is reminiscent of another historic undertaking: NASA's Voyager 2 mission to Neptune. Monday marks the 25th anniversary of Voyager's fly-by of Neptune and its moon Triton on August 25, 1989. The mission gave humanity its first close-up glimpse of the eighth planet from the sun and its largest satellite.
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NASA's New Horizons mission hurtles toward Pluto in historic 3 billion mile expedition
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New Horizons is set to reach the "dwarf planet" in July 2015
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NASA marks anniversary of Voyager 2 mission to Neptune and its moon Triton
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NASA: Voyager 2 mission offers a preview of sorts of New Horizons journey
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