THE SOUTHWORTH PLANETARIUM
207-780-4249       www.usm.maine.edu/planet
70 Falmouth Street  Portland, Maine 04103
43.6667° N,                    70.2667° W
Founded January 1970
               "Parting clouds, retreating winds, rejuvenated grasses and
awakening forests.    What a beautiful day."


THE DAILY ASTRONOMER
Wednesday, May 18, 2016
Night Light


It was sweet serendipity (i.e. dumb luck) that the Portland P.D. dash cam
just happened to record the spectacle in the wee hours on Tuesday morning,
May 17th.      This cam captured a rapid fireball that was seen throughout
New England and other Northeastern regions.      The Dash Cam footage
showed this flame out in its full splendor and left befuddled observers to
wonder, "What was that?!"

The media approached astronomy people across New England to inquire as to
the nature of this remarkable apparition.*   It was most likely a meteoroid
descending through the atmosphere.  Its descent generated enormous heat and
light, producing the dazzling display.     Most meteoroids are the size of
dust grains and the meteors they create are comparatively faint and
fleeting.     The body responsible for this now-celebrated fireball might
have been the size of a stone.

Meteoroids are pieces of flotsam roaming through outer space.    When they
encounter Earth, the planet's gravity draws them through the
atmosphere.     The meteoroid's rapid velocity excites nearby atoms, which
elevates their electrons into higher energy levels.   When the electrons
settle back to their original states, they release light with energies
equal to the difference between these levels.         Meteors are not
objects, but are instead the light we perceive when a meteoroid descends
through the atmosphere.     Meteorites are the remnants of the meteoroids
that survive the descent and are often recovered on Earth's surface.    It
is believed that the remains of this latest celestial interloper might have
landed somewhere in the wilds of western Maine.    The trick will be in its
recovery, for it is likely enshrouded in a forest and will be therefore
difficult to detect.  (It is only in science fiction movies that meteorites
glow brightly and impart superhuman powers onto the socially awkward.)

Some wonders if this light was an alien space craft flaming out in our
sky.      Well, anything is possible, but it seems strange that an alien
race advanced enough to traverse interstellar distances would be so
confounded by the encounter with a planet's atmosphere that their ship
would crash into it.    If, however, one encounters an implausibility** of
smoldering extraterrestrials looking perplexed, aggravated, and disheveled
as they stumble confusedly through Rangeley, then I will apologize for my
skepticism.

Earthlings are likely to experience many more fireballs in future.
Although scientists have cataloged most of the asteroids that could
potentially inflict significant damage to Earth (called PHA's, or
"Potentially Hazardous Asteroids,"). they aren't tracking the smaller
bodies because they are quite faint and as they don't pose a danger to us,
they generally aren't worth the time.

We never know when the next fire ball will appear.  We just have to
continue scanning the skies and, as always, we have to expect the
unexpected.










*Although yesterday I was somewhat distracted as I had just stolen a
bejeweled frog from a dryad inhabiting a nearby ash tree and was
frantically attempting to evade five people who were attempting to recover
it (true story).

**Yes, there are collective nouns for aliens, as well!