dipper@utastro.UUCP (Debbie Byrd) (06/07/85)
Friday and Saturday mornings, Jupiter is near the moon. More -- after this. June 7 Jupiter and the Moon Those out before dawn Friday morning may have noticed a bright object basking in the glare of the moon in the southern sky. That object is Jupiter -- near the moon Friday morning -- and still visible near the moon on Saturday. Jupiter is now high in the south when the sun comes up. It's moving rapidly toward its opposition -- when Jupiter is opposite the sun as seen from Earth -- as Earth speeds up behind this giant world in the endless race of planets around the sun. Earth and Jupiter will be traveling neck-and-neck in their respective orbits on August 4. Until then Jupiter will be getting brighter and rising earlier each night, as we catch up to this world from behind. If you see Jupiter and the moon Friday morning -- or if you get up to see them before dawn on Saturday -- you might think about a feature of Jupiter that's invisible to our eyes. Jupiter has a magnetic field, just as Earth does. But Jupiter's magnetosphere -- or sphere of magnetic influence -- is enormous. NASA spacecraft have found that Jupiter's magnetosphere extends nearly 10 million miles in the direction toward the sun -- and nearly 400 million miles on the planet's night side. In fact, the magnetosphere of Jupiter extends out beyond the orbit of Saturn! If you could illuminate Jupiter's magnetosphere Saturday morning -- when you see this world near Earth's own moon -- then the bold light we see as Jupiter would be surrounded by a tenuous shell twice the apparent size of our moon. Script by Deborah Byrd. (c) Copyright 1984, 1985 McDonald Observatory, University of Texas at Austin