*THE SOUTHWORTH PLANETARIUM*




*207-780-4249 <207-780-4249>       www.usm.maine.edu/planet
<http://www.usm.maine.edu/planet> 70 Falmouth Street  Portland, Maine 04103
43.6667° N,                    70.2667° W Founded January 1970*

*           "Made from the best stuff off Earth"*



*THE DAILY ASTRONOMER*

*Wednesday, April 20, 2016*

*Orion's Death and Other Catastrophes*


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*A SACRED SOUND JOURNEY INTO SPACE*


*Gong Concert at the Southworth Planetarium*

*Sunday, April 24, 2016  at 6:00 p.m.*

*$10 adults;  $5.00 children*


*http://usm.maine.edu/planet/gong-concert-sunday-april-24-2016-600-pm
<http://usm.maine.edu/planet/gong-concert-sunday-april-24-2016-600-pm>*

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*Our week delving into Pandora's depths continues.   For the benefit of
those hapless few who just linked their fates with this star-crossed
odyssey,  Pandora is our question vessel: the storage container for the
queries that we promptly neglected on receipt, but promised to address
presently.  And, as presently is presently the time, it is high time to put
pen to parchment.*




*"When will Orion die?  Or, when will the motions of the stars within Orion
make it unrecognizable?"  -Anonymous,  Pittsfield, ME*


*While Orion and the other constellations seem immortal to us humans, they
are similar to cloud  forms in that their structures will change by virtue
of the independent motion of their component parts.  For constellations,
these parts are the stars.    While some stars travel in clusters and
therefore have physical associations, most of the stars within a given
constellation are quite far from each other.  They only appear close
because the night sky does not reveal depth.  All stars also move, often at
speeds exceeding 100 miles per second.    As the stars are so remote, these
speeds won't shift their apparent positions relative to each other very
much even over many centuries.  However,  after tends of thousands of
years, these position shifts will become far more noticeable.*



*Orion the Hunter, the winter constellation that begins the night over in
the western sky, and the Big Dipper, an asterism within Ursa Major, provide
us with examples of how stellar motions can alter star patterns over
time.     In the graphic below, we see both the Big Dipper (above) and
Orion (below) at approximately 50,000 year intervals.   We see that 52,000
years ago, both the Big Dipper and Orion were starting to look similar to
the patterns we observe today.     Back then, the Big Dipper's bowl was
smaller and its handle straighter.    Orion's shield was bent and its head
-marked by the rapidly moving star Meissa- was raised high above the
shoulder.  In 48,000 years from now, Orion's head will vanish and his
curved shield will become a jumble of stars.    The Big Dipper's bowl will
have become wider and thinner, while its handle will be shaped like an
inverted "v."  Note that five stars within the Big Dipper (the two handle
stars closest to the bowl and the the bowl stars except for the upper star
farther from the handle) are part of the Ursa Major moving cluster. These
stars share a similar motion through space and therefore their positions
relative to each other won't change significantly during this time.      *



*This image shows  the Big Dipper (above) and Orion the Hunter (below) as
they appeared in the remote past, as they appear now, and as they will
appear in the distant future (Image by Martin Vargic)*



*Around the year 100,000 CE (or, if you prefer AD), the Big Dipper's bowl
will be unrecognizable.    So, too, will most of Orion.    The stars
comprising his bronze club and shield will have scattered.   The belt,
consisting of the stars Mintaka, Alnilam, and Alnitak, will still look very
much the same.  The hunter's knee stars, Saiph and Rigel, will also be in
about the same positions relative to this belt.   *


*So, to answer your question, about 100,000 years from now, one would be
hard pressed to see Orion the Hunter amongst the stars that now comprise
his pattern.   Then again, even at this point, one would still see the
belt.*


*An important caveat:   Betelgeuse, the star representing Orion's eastern
shoulder, will eventually go supernova, or explode.   Astronomers know this
catastrophic event will occur within the next one million years.  It might
occur within the next 100,000 years or it might not.  If it does, Orion's
eastern shoulder will then be gone, as well.*



*"In a previous article, you mentioned that the last total solar eclipse
will occur in about 600 million years.     Do you know where on Earth one
would have to be to observe this eclipse?"   -Jean S,  Biddeford, ME*



*Mathematical astronomy has enabled us to predict that total solar eclipses
will end in about 600 million years. They'll end at this time because the
moon, which is slowly moving away from Earth at about 4 cm/year, will then
be smaller in angular diameter than the Sun.   Therefore, whenever the moon
blocks the Sun, the result will be an annular eclipse: an eclipse in which
the outermost part of the Sun remains visible. *


*Unfortunately, we have no way of knowing where on Earth this final eclipse
will be observable.   Although mathematical astronomy is very powerful, it
remains limited.   Uncertainties within the Sun-Earth system, which are
slight over short time periods, accumulate over long durations.   In fact,
we cannot predict eclipse times or even planet positions even up to a
million years in the future, let alone 600 million.    My apologies for the
inconvenience.*