Explanation:
As you (safely!) watched the progress of yesterday's partial solar
eclipse, you probably also spotted a
giant
sunspot group.
Captured in this sharp telescopic image from October 22nd
the complex AR 2192 is beautiful to see, a
sprawling solar active region comparable in size
to the diameter of Jupiter.
Like other smaller sunspot groups,
AR 2192 is now crossing the
Earth-facing side of the Sun
and appears dark in
visible light because it is cooler than the surrounding surface.
Still, the energy stored in the region's twisted magnetic fields is
enormous and has already generated powerful explosions, including
two
X-class solar flares this week.
Coronal mass ejections (CMEs) associated with the flares have not
affected planet Earth, so far.
The forecast
for further activity from AR 2192 is still
significant though, as it swings across the center of
the solar disk and Earth-directed CMEs become possible.
Explanation: A New Moon
joined giant sunspot group AR 2192
to dim the bright solar disk
during Thursday's
much anticipated partial solar eclipse.
Visible
from much of North America, the Moon's broad silhouette
is captured in this extreme telephoto snapshot near
eclipse maximum from Santa Cruz, California.
About the size of Jupiter, the
remarkable AR 2192 itself
darkens a noticeable fraction
of the Sun, near center and below the curved lunar limb.
As the sunspot group slowly rotates
across the Sun and
out of view in the coming days its activity is difficult
to forecast.
But the timing of
solar
eclipses is easier to predict.
The next will be a total solar eclipse on
March 20, 2015.
Explanation:
Whatever hit Mimas nearly destroyed it.
What remains is one of the
largest impact craters on one of
Saturn's smallest moons.
The crater, named
Herschel after the 1789 discoverer of Mimas,
Sir William Herschel, spans about 130 kilometers and is
pictured above.
Mimas'
low mass produces a
surface gravity just strong enough
to create a
spherical body but weak enough to allow
such relatively large surface features.
Mimas is made
of mostly water ice with a smattering of rock - so it is
accurately described as a big dirty snowball.
The above image was taken during the 2010 February flyby of the
robot spacecraft Cassini now in
orbit
around Saturn.
A recent analysis
of Mimas's unusual wobble indicates that it might house a liquid water interior ocean.
Explanation:
What is that changing object in a cold
hydrocarbon sea of Titan?
Radar images from the robotic
Cassini spacecraft orbiting
Saturn
have been recording the surface of the cloud-engulfed moon Titan for years.
When imaging the flat -- and hence radar dark -- surface of the
methane and
ethane lake called
Ligeia Mare,
an object appeared in 2013 just was not there in 2007.
Subsequent observations in 2014 found
the object remained -- but had changed!
The featured image
shows how the 20-km long object has appeared and evolved.
Current origin speculative explanations include
bubbling foam and
floating solids, but no one is sure.
Future observations may either resolve the enigma or open up more speculation.
Explanation: As the Moon rose and
the Sun set on October 8,
a lunar eclipse was in progress seen from
Chongqing, China.
Trailing through
this composite time exposure, the rising Moon began as a
dark reddened disk in total eclipse near the eastern horizon.
Steadily climbing above the populous city's colorful
lights
along the Yangtze River, the moontrail grows brighter and broader,
until a bright Full Moon emerged from the Earth's shadow in
evening skies.
Although lunar eclipses are not always total ones,
this eclipse, along with last April's
lunar eclipse, were the first two of four consecutive total
lunar eclipses,
a series
known as a tetrad.
The final two eclipses of this tetrad will occur in early April
and late September 2015.
Explanation: This looks like
a near miss but the greenish coma and tail of
Comet
Siding Spring (C/2013 A1) are really
2,000 light-years or so away from the stars of open cluster
Messier 6.
They do appear close together though,
along the same line-of-sight in this gorgeous October 9th
skyscape toward the constellation
Scorpius.
Still, on Sunday, October 19th this comet really will be involved in
a near miss, passing within only
139,500
kilometers of planet Mars.
That's about 10 times closer than any known comet flyby of planet Earth,
and nearly one third the Earth-Moon distance.
While an impact with the nucleus is not a threat
the comet's dust, moving with a speed of about 56 kilometers per second
relative to the Red Planet, and outskirts of its
gaseous coma could interact with the thin Martian atmosphere.
Of course, the comet's close encounter will be followed
intently by spacecraft in
Martian orbit and rovers on the surface.
Comet Siding Spring Passes Mars Image Credit & Copyright: SEN/Damian Peach
Explanation:
Yesterday, a comet passed very close to Mars.
In fact, Comet C/2013 A1 (Siding Spring)
passed closer to the
red planet
than any comet has ever passed to Earth in recorded history.
To take advantage of this unique opportunity to study the close
interaction of a comet and a planet, humanity currently has five active
spacecraft orbiting Mars: NASA's
MAVEN,
MRO,
Mars Odyssey,
as well as
ESA's
Mars Express, and
India's
Mars Orbiter.
Most of these spacecraft have now sent back information that they have
not been damaged
by small pieces of the passing comet.
These spacecraft, as well as the two active rovers on the Martian surface -- NASA's
Opportunity and
Curiosity --
have taken data and images that will be downloaded to Earth for
weeks to come and likely studied for years to come.
The featured image
taken yesterday, however, was not taken from Mars but from Earth and shows
Comet Siding Spring on the lower left as it passed Mars, on the upper right.
Explanation:
Cosmic clouds form
fantastic shapes in
the central regions of emission nebula IC 1805.
The clouds are sculpted by stellar winds and radiation from
massive hot stars in the nebula's
newborn star cluster,
Melotte 15.
About 1.5 million years young,
the cluster stars are toward the right in this
colorful
skyscape, along with dark
dust clouds in
silhouette against glowing atomic gas.
A composite of narrowband and broadband telescopic images, the
view spans about 30 light-years and includes emission
from ionized hydrogen, sulfur, and oxygen atoms mapped to
green, red, and blue hues
in the popular Hubble Palette.
Wider field images
reveal that IC 1805's simpler,
overall outline suggests its popular name -
The
Heart Nebula.
IC 1805 is located about 7,500 light years away toward the
boastful constellation Cassiopeia.
Explanation:
One of the largest sunspot groups in recent years is now crossing the Sun.
Labelled
Active Region 2192, it has already thrown a
powerful solar flare
and has the potential to produce more.
The featured video
shows a time lapse sequence of the Sun in visible and ultraviolet light taken yesterday and incorporating the previous 48 hours.
AR 2192, rotating in from the left, rivals
Jupiter in size and is literally crackling with magnetic energy.
The active Sun
has caused some
spectacular auroras in recent days,
and energetic particles originating from
AR 2192 may help continue them over the next week.
Tomorrow, the Sun will appear unusual for even another reason: a
partial solar eclipse will be
visible before sunset from much of North America.
Explanation:
What causes sprite lightning?
Mysterious bursts of light in the sky that momentarily
resemblegigantic jellyfish have been recorded for over 25 years, but their root cause remains unknown.
Some thunderstorms have them -- most don't.
Recently, however,
high speed videos are better detailing how
sprites actually develop.
The featured video is fast enough -- at about 10,000 frames per second -- to
time-resolve
several sprite "bombs" dropping and developing into the
multi-pronged streamers that
appear onstill images.
Unfortunately, the
visual clues provided by
these videos
do not fully resolve the sprite origins mystery.
They do indicate to some researchers,
though, that sprites are more likely to occur when
plasma irregularities
exist in the upper atmosphere.
Galaxies in Pegasus Image Credit &
Copyright:
Alessandro Benedetti and Daniele Ceniti
(AeW Observatory)
Explanation: This wide,
sharp telescopic view reveals
galaxies
scattered beyond the stars and faint
dust
nebulae
of the Milky Way at the northern boundary of the high-flying constellation
Pegasus.
Prominent at the upper right is
NGC 7331.
A mere 50 million light-years away, the large spiral is one
of the brighter galaxies not included in
Charles
Messier's famous 18th century catalog.
The disturbed looking group of galaxies
at the lower left is
well-known as Stephan's Quintet.
About 300 million light-years distant, the quintet
dramatically illustrates a multiple galaxy collision, its
powerful, ongoing
interactions posed for a brief cosmic snapshot.
On the sky, the
quintet and
NGC 7331 are separated by about half a degree.
Too Close to a Black Hole Image Credit & Copyright: Alain Riazuelo
