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From: dipper@utastro.UUCP (Debbie Byrd)
Newsgroups: net.astro
Subject: StarDate: September 26 The Man Who Almost Found Uranus
Message-ID: <756@utastro.UUCP>
Date: Thu, 26-Sep-85 02:00:24 EDT
Article-I.D.: utastro.756
Posted: Thu Sep 26 02:00:24 1985
Date-Received: Tue, 1-Oct-85 08:04:51 EDT
Organization: U. Texas, Astronomy, Austin, TX
Lines: 37

An astronomer ALMOST made a monumental discovery on this date in 1756.
More on the man who almost found the planet Uranus -- after this.

September 26  The Man Who Almost Found Uranus

A German astronomer could have gone down in history on today's date in
the year 1756.  At that time, only six planets were known -- and only
six planets had ever been known since the dawn of history.  But, on
this date in 1756, Tobias Mayer saw a seventh planet -- Uranus.  Only
trouble was, he didn't know what he saw.  He recorded Uranus in his
catalogue as a fixed star.  If he'd just observed it twice within a few
days, he'd might have seen it move against the fixed star background.

Well, it was 25 more years before William Herschel saw Uranus -- and
noticed that it looked like a disk, instead of a pinpoint.  Stars
always appear as points because they're so far away.  But planets are
millions of times closer -- and they do look like disks through a
telescope.  So William Herschel became the first person in recorded
history to discover a planet, in the year 1781.

You can't really blame Mayer for not realizing the true nature of
Uranus.  After all, no one had ever discovered a planet, and people
didn't imagine that the boundaries of the solar system might extend
beyond the outermost known planet, Saturn.  When Herschel first
discovered Uranus, he thought he'd found a comet.

Mayer's was the first of twenty-three prediscovery observations of
Uranus.  Later, these so-called "ancient" observations were used to
chart the orbit of the new planet -- and to determine, among other
things, that it takes about 84 of our years to complete one orbit
around the sun.



Script by Deborah Byrd.

(c) Copyright 1984, 1985 McDonald Observatory, University of Texas at Austin


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