dipper@utastro.UUCP (Debbie Byrd) (08/01/84)
A planet and a star can be seen very close together in the west after sunset. We'll talk more about it -- in just a moment. July 25 Mercury and Regulus The bright planet seen LEAST often -- Mercury -- is now visible near a famous star -- Regulus, the heart of the lion in the constellation Leo. You can see the pair for yourself low in the west after sunset. Mercury is a little brighter than Regulus. As evening passes, and Earth spins beneath the sky, Mercury and Regulus will follow close behind the sun -- and sink below the western horizon. Mercury is the innermost world in our solar system -- and Regulus is a star -- well, really three stars -- all revolving around each other -- located 85 light-years away. Regulus and the planet Mercury have very little in common -- but they just happen to be located now in nearly the same direction along our line of sight. Wednesday evening, they'll be only 0.8 degrees apart on the dome of Earth's sky -- and they'll still be pretty close Thursday evening. Mercury is now about as high in the west as it'll get this time around. It'll soon plunge back into the sun's glare -- due to its own rapid motion around the sun. On the other hand, Regulus is also due to be lost in the sun's glare soon -- not because of any motion of the star -- but because Earth is moving -- and our night sky is now about to point away from the region of space that contains this particular star. So take a look -- Mercury and the star Regulus -- now low in the west after the sun goes down. And by the way tomorrow we'll talk about what you can see now in the sky before dawn. Script by Deborah Byrd. (c) Copyright 1983, 1984 McDonald Observatory, University of Texas at Austin