dipper@utastro.UUCP (Debbie Byrd) (08/25/85)
On this date in 1989, the Voyager spacecraft may make a first encounter with Neptune. More -- after this. August 25 On To Neptune Yesterday we talked about the upcoming Voyager 2 spacecraft encounter with the planet Uranus -- due to take place this coming winter. Voyager has been in space now for eight years -- and it's showing signs of old age. But if it survives past the encounter with Uranus, it will go on to encounter Neptune. Closest approach would be on this date in the year 1989 -- just five days beyond the 12th anniversary of the launch of Voyager 2. Neptune has long been regarded as a near twin to the planet Uranus. There's a great riddle concerning the question of rings for the planet -- since Neptune is now the only gas giant world NOT known to have them. There's evidence that Neptune does have rings. Voyager 2 would tell us for sure. It so happens that Neptune is now the most distant from the sun of all known worlds in our solar system. That has been the case since 1979, when Pluto's orbit brought it closer to the sun than Neptune. Pluto will orbit inward from Neptune until the end of this century. Neptune has two known moons -- large Triton and little Nereid -- and there are suggestions of a possible third moon from ground-based observations made in 1981. The large moon, Triton, is a fascinating world in itself -- almost as large as the planet Mercury -- with a possible ocean of liquid nitrogen on its surface! If all goes well, Voyager 2 will explore distant Neptune and its moons -- with closest approach on today's date in 1989. Script by Deborah Byrd. (c) Copyright 1984, 1985 McDonald Observatory, University of Texas at Austin
bob@islenet.UUCP (Bob Cunningham) (08/31/85)
> There's a great riddle concerning the question of rings for the planet > -- since Neptune is now the only gas giant world NOT known to have > them. There's evidence that Neptune does have rings. Voyager 2 would > tell us for sure. More precisely, there have been a few, inconsistent reports of observations of rings or additional satellites around Neptune. The reports were few and inconsistent ... until August 19th when Brahic, Sicardy, Perrier and McLaren observed an occultation of Neptune at the Canada-France-Hawaii telescope atop Mauna Kea. The star disappeared behind Neptune, reappeared 73 minutes later, then dimmed a bit 13 minutes later for less than two seconds. Their conclusion: "...indicating the presence of an object or group of objects" in orbit around the planet. In short, a very strong indication of a ring system. NASA's infrared telescope, also on Mauna Kea, verified with similar observations at the same time. Of course, no one will know for sure until the Voyager II rendezvous... -- Bob Cunningham {dual|vortex|ihnp4}!islenet!bob Hawaii Institute of Geophysics