THE SOUTHWORTH PLANETARIUM
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43.6667° N                   70.2667° W
Altitude:  10 feet below sea level
Founded January 1970
Julian Date: 245913.16
2019-2020:  CX
            "Half a century on Earth"

THE DAILY ASTRONOMER
Wednesday, March 4, 2020
Flarewell!

They're gone.
We're going to miss them immensely.
They'll be the focus of today's DA, even though, while they are
astronomically technical, they're not technically astronomical.

*Iridium Flares!*

Have you ever seen one?
If not, we're afraid you won't.    They have followed the fast- fading
phantom trails they often impressed onto the firmament.     They were those
fleeting and often brilliant lights that seemed to emerge out of the void
for a few seconds before vanishing just as quickly.    They were the
delight of astronomers around the world.  Now they belong to the ages.


[image: Iridium_satellite-e1355156620425.jpeg]

Well, there it is: an image of the Iridium satellite now on display at the
Air and Space Museum. In the late 1990s the Iridium SCC company launched
sixty-six of these communications satellites that they planned to use for
world wide communication system.    They had intended to launch
seventy-seven hence the named Iridium, the element with the atomic number
of 77.    This first fleet of Iridium satellites has now been replaced by
the NEXT generation: an evolutionary step up from the initial vessels.
Unfortunately, these new Iridium satellites don't produce flares.

[image: 93dee31e7389756173ebfb4f4da1e982.jpg]

We used to see Iridium flares because sunlight would at times reflect off
their panels or antennae in such as way as to direct the light toward
Earth-bound observers.    As the angles had to be quite precise, the events
were highly localized.  A bright flare in one town would be a dull flare in
an abutting community and no flare at all farther away.     This limitation
is in contrast to the International Space Station visible over a wide
region.

One shouldn't despair, however.
The night sky is as intensely alive with activity as ever.    The Iridium
flares were a literal flash in the pan: a phenomenon that lasted a little
more than twenty years.    So much more remains to be beheld and admired,
including the battalions of Starlink satellites that, while perhaps putting
the kibosh on ground based astronomy forever, are quite a sight!   No, we
don't regard that as a good trade off, actually.

So, farewell to the flares that once scorched our sky.    It's a shame
they're gone as we hardly knew ye.



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