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From: dipper@utastro.UUCP (Debbie Byrd)
Newsgroups: ut.stardate,net.astro
Subject: Stardate jul 18
Message-ID: <238@utastro.UUCP>
Date: Wed, 25-Jul-84 02:00:23 EDT
Article-I.D.: utastro.238
Posted: Wed Jul 25 02:00:23 1984
Date-Received: Sat, 21-Jul-84 04:22:58 EDT
Organization: UTexas Astronomy Dept., Austin, Texas
Lines: 43




Early morning risers can look for a star whose name means Wonderful.
More on Mira -- in a moment.

July 18  Mira's Maximum

A few hours before dawn the constellation Cetus the Whale rises above
the eastern horizon -- to be visible in the southeast.  Cetus is not an
especially prominent constellation -- but it contains a star known as
Mira -- which is Latin for Wonderful Star.

Mira earned this name because it was the first variable star
discovered.  Variable stars are stars that change in brightness.
Sometimes Mira is bright enough to be seen with the naked eye -- and at
other times it dims into invisibility.

In the year 1596, an astronomer plotted the location of Mira while
making a map of the stars.  He must have been surprised when Mira
disappeared from view.

But Mira returned to visibility again -- it always does.  Many
different types of variable stars are now known to exist.  Some
brighten and fade with great regularity -- others are a little
irregular -- like Mira, which has a cycle of about eleven months.  Mira
sometimes reaches maximum brightness a little ahead of schedule -- and
it's sometimes a little brighter than usual.  That was the case last
year -- Mira at maximum was a little on the bright side.  This year it
just so happens that Mira's maximum brightness occurred about mid-June
-- when the star was on the other side of the sun from the Earth and
hidden in the sun's glare.  Mira has now come out of the sun and may be
in the predawn sky.  The star is now on the down side of its cycle --
getting dimmer -- but possibly still visible to the naked eye.  The
only way to know for sure is to take a look.

(Sky chart??)

Script by Diana Hadley and Deborah Byrd.

(Conversation with Janet Mattei, AAVSO, 4-5-84)

(c) Copyright 1983, 1984 McDonald Observatory, University of Texas at Austin