Explanation:
One of the brightest galaxies in planet Earth's sky is similar in size
to our Milky
Way Galaxy: big, beautiful M81.
This grand spiral galaxy can be found toward the northern constellation of the Great
Bear
(Ursa Major).
This superbly
detailed view reveals M81's bright yellow nucleus, blue
spiral arms, and sweeping cosmic dust lanes with a scale comparable to
the
Milky Way.
Hinting at a disorderly past,
a remarkable dust lane actually runs straight through the
disk, to the left of the galactic center,
contrary to M81's
other prominent
spiral features.
The errant
dust lane may be the lingering result of
a close encounter between
M81 and its smaller companion galaxy, M82.
Scrutiny of variable stars in
M81 has yielded one of the best
determined
distances for an external galaxy -- 11.8 million light-years.
Explanation:
Obscuring the rich starfields of northern Cygnus, dark nebula LDN 988
lies near the center of
this cosmic skyscape.
Composed with telescope and camera, the scene is some 2 degrees
across.
That corresponds to 70 light-years at the estimated 2,000 light-year
distance of LDN 988.
Stars are forming within
LDN 988,
part of a larger complex of
dusty molecular clouds
along the plane of our Milky Way galaxy sometimes
called the Northern Coalsack.
In fact, nebulosities associated with young stars abound in the region,
including variable star V1331 Cygni shown in the inset.
At the tip of a long dusty filament and partly surrounded by a curved
reflection nebula,
V1331 is thought to
be a T Tauri star, a sun-like
star still in the early stages of formation.
Explanation:
The Crab Nebula is cataloged as M1, the first object on
Charles
Messier's famous 18th century list of things which are not comets.
In fact,
the
Crab is now known to be a
supernova remnant,
debris from the death explosion of a massive star,
witnessed
by astronomers in the year 1054.
This sharp,
ground-based telescopic view uses
narrowband data to track emission from ionized oxygen and hydrogen atoms
(in blue and red) and explore the tangled filaments within
the still expanding cloud.
One of the most exotic objects known to modern astronomers,
the Crab Pulsar,
a neutron star spinning 30 times a second,
is visible as a bright spot near
the
nebula's center.
Like a cosmic dynamo,
this collapsed remnant of the stellar core
powers the Crab's emission across the electromagnetic spectrum.
Spanning about 12 light-years, the Crab Nebula is a mere
6,500 light-years away in the
constellation
Taurus.
Explanation: Solar active region AR2192
was the largest recorded sunspot group of the last 24 years.
Before rotating off the
Earth-facing side of the Sun at the end of
October, it produced a whopping
six energetic X-class flares.
Its most intense flare was captured on October 24 in this
stunning view from the orbiting
Solar Dynamics Observatory.
The scene is a
color combination of
images made at three different wavelengths of
extreme ultraviolet light;
193 angstroms shown in blue, 171 angstroms in white, and 304 angstroms
in red.
The emission, from highly ionized Iron and Helium atoms, traces
magnetic field lines looping through the hot
plasma
of the Sun's outer
chromosphere
and corona.
Beneath, the cooler solar photosphere appears dark at extreme ultraviolet
wavelengths.
The exceptionally sharp composite image has been processed
with a new mathematical algorithm
(NAFE)
that adapts to noise and brightness in extreme ultraviolet
image data to reliably enhance small details.
Explanation:
What would it look like to fly over Titan?
Radar images from
NASA's robotic
Cassini satellite in orbit around
Saturn have been
digitally compiled to simulate such a flight.
Cassini has swooped past
Saturn's cloudiest moon several times since it arrived at the ringed planet in 2004.
The virtual flight
featured hereshows numerous lakes colored black and mountainous terrain colored tan.
Surface regions without detailed vertical information appear more flat,
while sufficiently mapped regions have their heights digitally stretched.
Among the basins visualized is
KrakenMare,
Titan's largest lake which spans over 1,000 kilometers long.
Titan's lakes are different from
Earth's lakes in that they are composed of
hydrocarbons with similarities to liquid
natural gas.
How Titan's lakes were created and why they survive continues to be a topic of research.
Explanation:
What creature lurks near the red Lagoon nebula?
Mars.
This gorgeous
color deep-sky photograph has captured the red planet passing below two
notable nebulae -- cataloged by the 18th century cosmic registrar
Charles
Messier as M8 and M20.
M20 (upper right of center),
the Trifid Nebula, presents a striking contrast in
red/blue colors and dark dust lanes.
Just below
and to the left is the expansive, alluring red glow of M8,
the Lagoon Nebula.
Both nebulae are a few thousand
light-years distant.
By comparison,
temporarily situated below them both,
is the dominant "local" celestial beacon
Mars.
Taken late last month posing near its southernmost point in Earth's sky,
the red planet
was 14 light-minutes away.
Explanation:
Look through the cosmic cloud cataloged as NGC 281
and you might miss the stars of open cluster
IC 1590.
But, formed
within
the nebula, that cluster's young, massive stars
ultimately power the pervasive
nebular glow.
The eye-catching shapes looming in
this portrait
of NGC 281 are sculpted columns and dense
dust globules
seen in silhouette, eroded by intense, energetic winds and radiation
from the hot cluster stars.
If they survive long enough,
the dusty structures could also be sites of future star formation.
Playfully called
the Pacman Nebula because of its overall shape,
NGC 281 is about 10,000 light-years away in the constellation
Cassiopeia.
This sharp composite image was made through
narrow-band filters,
combining emission from the nebula's hydrogen, sulfur, and oxygen
atoms in green, red, and blue hues.
It spans over 80 light-years at the estimated distance of NGC 281.
Explanation:
Looping through the Jovian system in the late 1990s, the
Galileo spacecraft
recorded stunning views of Europa and uncovered
evidence that the moon's icy surface likely hides
a deep, global ocean.
Galileo's Europa image data has been
newly
remastered here, using improved new calibrations to
produce a color image
approximating what the human eye might see.
Europa's long curving fractures hint at the subsurface
liquid water.
The tidal flexing
the large moon experiences in its elliptical orbit
around Jupiter supplies the energy to keep the ocean liquid.
But more
tantalizing is the possibility
that even in the
absence of sunlight that process could also supply the energy to
support life,
making Europa
one of the best places to look
for life beyond Earth.
What kind of life could thrive in a deep, dark, subsurface ocean?
Consider planet Earth's own
extreme
shrimp.
