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Neptune, the 8th planet outward from the sun, is presently the most distant planet in the solar system. That's because the International Astronomical Union reclassified Pluto as a "dwarf planet" in 2006. By the way, Neptune circles the sun three times for every two times that Pluto does.
You can see Neptune with good binoculars or a telescope, but you need to know right where to look. At this time of year, you have to stay up late or wake up early to see this world. Moreover, you'll probably need a detailed sky chart to find Neptune's place in the sky.
Familiar with the bright star Fomalhaut or the constellation Aquarius? If so, you can try to star-hop to Neptune. Our sky chart also points out the star Skat (Delta Aquarii), the radiant point for the upcoming Delta Aquarid meteor shower, which peaks in late July.
Neptune is the only solar system planet that you absolutely cannot see without optics. Uranus, the 7th planet outward, is faintly visible to the unadided eye on a clear, dark night.
Wish Neptune a Happy Birthday, as it finishes up its first trip around the sun on July 12, 2011!
Galileo Galliei's observation:- Every one knows how difficult it is to see planets of our solar system, beyond Saturn. This difficulty prevented him from discovering Neptune because it was changing from forward motion to "retrograde" motion between 28 December 1612 and 27 January 1613 - and hence was judged as a fixed star by him. In a sense, our solar system is a "troubling" one as it does not contain any real-retrograde planet but does have retrograde moons around Jupiter, Saturn - discovered 100 years ago. It troubled not only Galileo Galliei in the past but is causing "conceptual" touble for learning "O" / H.S.C. level physics also. Write me on dvsathe@gmail.com for more information.