dipper@utastro.UUCP (Debbie Byrd) (04/26/85)
Earth has just passed Pluto in the race around the sun -- and we're gaining on the other outer worlds as well. More -- after this. April 26 The Race Around the Sun This week the Earth caught up to and passed the outer planet Pluto in the race around the sun. We travel much faster in orbit than Pluto does, and we go much less distance to complete one orbit around the sun. We journey around the sun 248 times for a single orbit of Pluto -- so a year on Pluto equals 248 Earth-years. When Earth and an outer world are neck-in-neck in the race around the sun, the outer world is said to be at opposition. Pluto's opposition was this past Tuesday, April 23. Today we're slightly ahead of Pluto -- due to catch up and pass it again on today's date next year. We catch up to Pluto at nearly the same date next year because Pluto moves so slowly around the sun. It has moved through only about one-quarter of its orbit since its discovery in 1930. When it was discovered, Pluto was seen against the background of stars in the constellation Gemini. It won't make it back to that same point in the heavens until the year 2177. Between 1930 and 2177, only one year on Pluto will have passed. The other outer planets are all moving around the sun in their respective orbits, with Jupiter in the lead, then Neptune, Uranus, Saturn, and finally Pluto -- all in the same general region of the solar system. Coming up from behind, we'll pass each of these outer worlds in turn. First Pluto, this week -- then Saturn in May -- Uranus and Neptune in June -- and finally Jupiter in August. Script by Deborah Byrd. (c) Copyright 1984, 1985 McDonald Observatory, University of Texas at Austin