| MOTHER'S
DAY: Give your mom a truly heavenly gift on May
11th--a subscription to Space
Weather PHONE! |
|
|
MOON & MARS:
Do you know where Mars is? Let the Moon be your guide. Tonight the
crescent Moon is passing by the twins of Gemini and making a beeline
for the red planet. You can't miss it. Look west after sunset for
a heavenly orientation: sky
map.
DOOMED PLANET TRANSIT:
About 1300 light years from Earth, in the constellation Hercules,
a planet named TrES-3 twice as massive as Jupiter is slowly spiraling
into its parent star. It orbits so close to the star, in fact, that
it occasionally passes in front and dims the starlight--a telltale
fluctuation that led to its discovery by astronomers
in May 2007.
On May 3rd, 2008, Anthony Ayiomamitis
observed a transit of TrES-3 from Greece "using only a 6.3-inch
apochromatic refractor," he says. "I am delighted to present
you with a light curve, which most beautifully illustrates the 105-minute
event."
"At some point," he notes, "this exoplanet will
not be available for study due to its impending collision into its
sun. One can only wonder
and dream how sunrises and sunsets will appear on this foreign
world, if at all, and whether it has moons similar to Luna dominating
the night sky with breath-taking eclipses and lunar phases, and
if its atmosphere is a playground of light including auroras, NLCs
and meteor showers."
"What makes photometry of this exoplanet most challenging,"
he adds, "is the fact that its parent star is dim at magnitude
12.17 and the planet makes only very small changes in the overall
brightness, from 12.170 to 12.195." Click
here to learn the details of these skillful measurements.
RANDOM METEOR:
Last week in the Black Forest of Germany, Achim
Schaller was testing his new Nikon
D300 by attaching it to his backyard telescope and taking a
few pictures of the Leo Triplet of galaxies. "When I looked
over the images," he says, "I found one of them had caught
a meteor in flight."
There was no meteor shower in progress on April 29th when Schaller
took the picture. So where did the meteor come from? Scroll down
for the answer:
It was a "sporadic" or random meteor. Every night, thousands
of them flit across the sky mostly unseen because they are so dim.
The one in Schaller's photo registered 10th magnitude, too faint
by a factor of 40 to see with the human eye. (Note: Not all random
meteors are faint. Standing under the stars on a dark, moonless
night, you can count a few sporadics every hour plainly visible
to the unaided eye. Most, however, require a telescope.)
Random meteors come not from any particular comet or asteroid,
but from a diffuse swarm of space dust that fills the inner solar
system. "Every day Earth sweeps up about 22 metric tons of
this material," says Bill Cooke of NASA's Meteoroid Environment
Office. He estimates that "40% of that mass, or 8.8 metric
tons, turns into meteors of 10th magnitude or brighter: graph."
If those metric tons arrived in a single lump, the result would
be a fantastic fireball in the sky and possibly a scattering of
meteorites on the ground. Instead, the swept-up material arrives
mainly as microscopic bits and pieces, producing a faint drizzle
of year-round meteor activity. The meteoroid in Schaller's photo
probably had a mass "of around 0.00005 grams," notes Cooke.
Tiny, but beautiful!
April
2008 Aurora Gallery
[Aurora Alerts] [Night-sky
Cameras]
|
