Voyager - Neptune
 
 
Voyager                              2's view of Neptune, 57,000,000 kilometers (35 million                              miles) away (Click on the image for a larger view)
In the                        summer of 1989, NASA's Voyager 2 became the first spacecraft                        to observe the planet Neptune, its final planetary target.                        Passing about 4,950 kilometers (3,000 miles) above Neptune's                        north pole, Voyager 2 made its closest approach to any planet                        12 years after  leaving Earth in 1977. Five hours later, Voyager                        2 passed about 40,000 kilometers (25,000 miles) from Neptune's                        largest moon, Triton, the last solid body the spacecraft                        will have an opportunity to study.
Neptune                        is one of the class of planets -- all of them beyond the                        asteroid belt -- known as gas giants; the others in this                        class are Jupiter, Saturn and Uranus. These planets are                        about 4 to 12 times greater in diameter than Earth. They                        have no solid surfaces but possess massive atmospheres that                        contain substantial amounts of hydrogen and helium with                        traces of other gases.
Voyager                        1, launched September 5, 1977, visited Jupiter in 1979 and                        Saturn in 1980. It is now leaving the solar system, rising                        above the ecliptic plane at an angle of about 35 degrees,                        at a rate of about 520 million kilometers a year.
Voyager                        2, launched August 20, 1977, visited Jupiter in 1979, Saturn                        in 1981 and Uranus in 1986 before making its closest approach                        to Neptune on August 25, 1989. Voyager 2 traveled 12 years                        at an average velocity of 19 kilometers a second (about                        42,000 miles an hour) to reach Neptune, which is 30 times                        farther from the Sun than Earth is. Voyager observed Neptune                        almost continuously from June to October 1989. Now Voyager                        2 is also headed out of the solar system, diving below the                        ecliptic plane at an angle of about 48 degrees and a rate                        of about 470 million kilometers a year.
Both                        spacecraft will continue to study ultraviolet sources among                        the stars, and their fields and particles detectors will                        continue to search for the boundary between the Sun's influence                        and interstellar space. If all goes well, we will be able                        to communicate with the two spacecraft for another 20 years,                        until their radioactive power sources can no longer supply                        enough electrical energy to power critical subsystems.
  This page was last updated       June 11, 2014