Explanation: Albert Einstein's
general theory of relativity, published 100 years
ago this month, predicted the phenomenon of gravitational lensing.
And that's what gives these distant galaxies such a whimsical appearance,
seen
through the looking glass of X-ray and optical
image data from the Chandra and Hubble space telescopes.
Nicknamed the Cheshire Cat galaxy group, the group's two
large elliptical galaxies are suggestively framed by arcs.
The arcs are optical images
of distant background galaxies
lensed by the foreground group's total distribution
of gravitational mass dominated by dark matter.
In fact the two large elliptical "eye" galaxies represent
the brightest members of their own galaxy groups which are merging.
Their relative collisional speed of nearly 1,350 kilometers/second
heats gas to millions of degrees producing the X-ray glow shown
in purple hues.
Curiouser about
galaxy group mergers?
The Cheshire Cat
group grins
in the constellation Ursa Major, some 4.6 billion light-years away.
Explanation:
Planet Earth's horizon stretches across this
recent Solar System group portrait, seen from
the southern hemisphere's Las Campanas Observatory.
Taken before dawn it
traces
the ecliptic with
a line-up familiar to November's early morning risers.
Toward the east are bright planets Venus, Mars, and
Jupiter as well as Regulus, alpha star of the constellation Leo.
Of course
the planets are immersed in the faint glow of zodiacal
light, visible from the dark site rising at an angle from the
horizon.
Sometimes known as the false dawn, it's
no accident the zodiacal light
and planets both lie
along the
ecliptic.
Formed in the flattened
protoplanetary disk,
the Solar System's planet's all orbit near the ecliptic plane,
while dust near the plane scatters sunlight, the
source of the faint
zodiacal glow.
Explanation:
Why are there unusual pits on Pluto?
The indentations were discovered during the
New Horizons spacecraft's flyby of the
dwarf planet in July.
The largest pits span a kilometer across and dip tens of meters into a lake of
frozen nitrogen,
a lake that sprawls across
Sputnik Planum,
part of the famous light-colored heart-shaped region named
Tombaugh Regio.
Although most pits in the Solar System are created by impact craters,
these depressions look different --
many are similarly sized, densely packed, and aligned.
Rather, it is thought that something has caused
these specific areas of ice to
sublimate and evaporate away.
In fact, the lack of
overlying impact craters indicates these pits formed relatively recently.
Even though the robotic New Horizons is now off to a
new destination, it continues to beam back to Earth
new images and data from its
dramatic encounter with
Pluto.
Explanation:
The constellation of Orion is much more than three stars in a row.
It is a direction in space that is
rich with impressive nebulas.
To better appreciate this well-known swath of sky, an
extremely long exposure was taken over many clear nights in 2013 and 2014.
After 212 hours of camera time and an
additional year of processing, the featured 1400-exposure collage spanning over 40 times the
angular diameter of
the Moon emerged.
Of the many interesting details that have become visible, one that particularly draws the eye is
Barnard's Loop, the bright red circular filament arcing down from the middle.
The Rosette Nebula is not the giant red nebula near the top of the image -- that is a larger but lesser known nebula known as Lambda Orionis.
The Rosette Nebulais visible, though: it is the red and white nebula on the upper left.
The bright orange star just above the frame center is
Betelgeuse, while the bright blue star on the lower right is
Rigel.
Other famous nebulas visible include
the Witch Head Nebula,
the Flame Nebula,
the Fox Fur Nebula, and, if you know just where to look,
the comparatively small Horsehead Nebula.
About those
famous three stars that cross the belt of
Orion the Hunter --
in this busy frame they can be hard to locate, but a
discerning eye will find them just below and to the right of the image center.
Explanation:
This moon is doomed.
Mars,
the red planet named for the
Roman god of war, has two tiny moons,
Phobos and
Deimos, whose
names are derived from the Greek for Fear and
Panic.
These martian moons may well be captured
asteroids
originating in the main asteroid belt between Mars and
Jupiter
or perhaps from even more distant reaches of the Solar System.
The larger moon, Phobos, is indeed seen
to be a cratered, asteroid-like object in this
stunning color image from the robotic
Mars Reconnaissance Orbiter,
recorded at a resolution of about seven meters per pixel.
But Phobos
orbits so close to Mars - about 5,800 kilometers above the surface compared to 400,000 kilometers
for our Moon - that gravitational
tidal forces
are dragging it down.
A recent analysis
of the long grooves indicates that they may result from global stretching caused by
tides --
the differing force of Mars' gravity on different sides of
Phobos.
These grooves may then be an early phase in the
disintegration of
Phobos into a ring of debris around Mars.
Explanation:
What's the closest active galaxy to
planet Earth?
That would be Centaurus A, only 11 million light-years distant.
Spanning over 60,000 light-years, the peculiar elliptical galaxy is
also
known as NGC 5128.
Forged in a
collision of two
otherwise normal galaxies, Centaurus A's
fantastic jumble of young blue star clusters, pinkish star forming
regions, and imposing dark dust lanes are seen here in remarkable detail.
The
colorful galaxy portrait is a composite of image data
from space- and ground-based telescopes large and small.
Near
the galaxy's center, left over cosmic debris is steadily
being consumed by a central black hole with a billion times
the mass of the Sun.
As
in other active galaxies, that process generates the radio,
X-ray, and gamma-ray energy radiated by Centaurus A.
The Pelican Nebula in Gas, Dust, and Stars Image Credit & Copyright: Roberto Colombari
Explanation:
The Pelican Nebula is slowly being transformed.
IC 5070, the official designation, is divided from the larger
North America Nebula by a
molecular cloud filled with dark
dust.
The
Pelican,
however, receives much study because it is a particularly active mix of
star formation and evolving gas clouds.
The featured picture
was produced in three specific colors -- light emitted by
sulfur,
hydrogen, and
oxygen --
that can help us to better understand these interactions.
The light from young energetic stars is slowly transforming the cold gas to hot gas,
with the advancing boundary
between the two, known as an
ionization front, visible in bright orange on the right.
Particularly dense
tentacles of cold gas remain.
Millions of years from now this nebula might no longer
be known as the
Pelican,
as the balance and placement of stars and gas
will surely leave something that appears completely different.
Explanation: Long
shadows are cast
by a low Sun across this rugged looking terrain.
Captured by New Horizons,
the scene is found just south of the southern tip Sputnik Planum,
the informally named smooth, bright heart
region of Pluto.
Centered is a feature provisionally known as Wright Mons, a broad,
tall mountain, about 150 kilometers across and 4 kilometers high, with
a 56 kilometer wide, deep summit depression.
Of course, broad mountains with central craters are found
elsewhere in the Solar System, like
Mauna Loa on planet Earth and
Olympus Mons on Mars.
In fact, New Horizons scientists announced
the striking similarity of
Pluto's Wright Mons, and
nearby Piccard Mons, to large shield volcanoes strongly suggests
the two could be giant cryovolcanoes that once erupted
molten ice from the interior of the cold, distant world.
Explanation: This
telescopic close-up shows off the otherwise faint emission
nebula IC 410.
It also features two remarkable inhabitants of the cosmic pond
of gas and dust below and right of center,
the tadpoles
of IC 410.
Partly obscured by foreground dust, the nebula itself
surrounds NGC 1893, a young
galactic cluster of stars.
Formed in the interstellar cloud a mere 4 million years ago, the
intensely hot, bright
cluster stars energize the glowing gas.
Composed of denser cooler gas and dust,
the tadpoles are around 10 light-years long and are
likely sites of ongoing star formation.
Sculpted by
winds and radiation from the cluster stars,
their heads are outlined by bright ridges of ionized gas while
their tails trail away from the cluster's central region.
IC 410 lies some 10,000 light-years away,
toward the nebula-rich constellation Auriga.
Explanation:
Is star AE Aurigae on fire? No.
Even though
AE Aurigae is named the flaming star,
the surrounding nebula
IC 405 is named the
Flaming Star Nebula, and the region appears to have the color of
fire, there is no fire.
Fire,
typically defined as the rapid molecular acquisition of
oxygen,
happens only when sufficient oxygen is present and is not important
in such high-energy, low-oxygen environments such as stars.
The material that appears as
smoke is mostly
interstellar hydrogen,
but does contain smoke-like dark filaments of carbon-rich
dust grains.
The bright star
AE Aurigae, visible toward the right near the nebula's center, is so hot it is blue,
emitting light so energetic it knocks
electrons away from surrounding gas.
When a proton
recaptures an electron, light is emitted, as seen in the surrounding
emission nebula.
Pictured above, the
Flaming Star nebula lies about 1,500
light years distant, spans about 5
light years,
and is visible with a small telescope toward the
constellation of
the Charioteer (Auriga)
Explanation:
It is the largest and most sophisticated object ever built off the Earth.
It has taken numerous spaceflights and over a decade to
construct.
The International Space Station
(ISS) is currently the
premiere habitat
for humans in Earth orbit, and an amalgamation of sophisticated orbiting
laboratories that have examined everything from the formation of
new materials and medicines created in
microgravity -- to the limitations of the human body -- to the
composition of the universe.
This month, the
ISS is
celebrating 15 years of continuous human habitation.
The ISS has been visited by astronauts from 15 countries, so far, and has
international partners led by
NASA (USA),
Roscosmos (Russia),
CSA (Canada),
JAXA (Japan), and
ESA (Europe).
The featured animation
shows the piece-by-piece construction of the
ISS from 1998 to 2011.
Spanning the length of a football field, the
ISS can be
seen as an unusually
bright spot drifting slowly overhead by anyone who knows
when and where to look.
Earth and Milky Way from Space Image Credit: NASA,
Scott
Kelly
Explanation: Since
November 2000, people have been living
continuously on the International Space Station.
To celebrate humanity's 15th anniversary
off planet Earth,
consider this
snapshot
from space of our galaxy and
our home world posing together beyond the orbital outpost.
The Milky Way stretches below the curve of Earth's limb in the scene
that also records a faint red, extended airglow.
The galaxy's central bulge appears with starfields
cut by dark rifts of obscuring interstellar dust.
The picture was taken by Astronaut Scott Kelly on August 9, 2015,
the 135th day of his
one-year mission in space.
Explanation:
Spiral galaxy NGC 3169 appears to be unraveling
in
this cosmic scene, played out some 70 million light-years away
just below
bright star Regulus toward the faint constellation Sextans.
Its beautiful spiral arms are distorted into sweeping tidal
tails as NGC 3169 (top) and neighboring NGC 3166 interact
gravitationally, a common fate even
for bright galaxies in the local universe.
In fact, drawn out stellar arcs and plumes,
indications of gravitational interactions,
seem rampant in the deep and colorful
galaxy
group photo.
The picture
spans
20 arc minutes, or about 400,000 light-years
at the group's estimated distance, and includes smaller, dimmer NGC 3165
at bottom right.
NGC 3169 is also known to shine across the spectrum from
radio to X-rays,
harboring
an active galactic nucleus that is likely the
site of a supermassive black hole.
Explanation:
NGC 1333 is seen in visible light as
a reflection nebula,
dominated by bluish hues characteristic of starlight reflected by
interstellar dust.
A mere 1,000 light-years distant toward the heroic constellation
Perseus,
it lies at the edge of a large,
star-forming molecular cloud.
This striking close-up spans
about two full moons on the sky or just over
15 light-years at the estimated distance of NGC 1333.
It shows details
of the dusty region along with hints of contrasting red emission from
Herbig-Haro
objects, jets
and shocked glowing gas emanating from recently formed stars.
In fact, NGC 1333 contains hundreds of stars less than
a million years old, most still
hidden
from optical telescopes by the
pervasive stardust.
The chaotic environment may be similar to one in which our own Sun
formed over 4.5 billion years ago.
Explanation:
The Great Nebula
in Orion, also known as M42, is one of the
most famous nebulas in the sky.
The star forming region's glowing gas clouds and hot young stars
are on the right in this sharp and colorful image that includes the bluish reflection nebulae
NGC 1977 and friends on the left.
Located at the edge of an otherwise invisible
giant molecular
cloud complex,
these eye-catching nebulas represent only a small
fraction of this galactic neighborhood's wealth of
interstellar material.
Within the
well-studiedstellar nursery, astronomers have also
identified
what appear to be numerous infant planetary systems.
The gorgeous skyscape spans nearly two degrees or about 45
light-years
at the Orion Nebula's estimated distance of 1,500 light-years.
Comet ISON Being Destroyed by the Sun Video Credit: NASA,
ESA,
SOHO
Explanation:
Most comets don't survive a close encounter with the Sun.
Two years ago this month, though,
Comet ISON was thought by some to be big enough to withstand its perilous sungrazing dive.
The
featuredvideo
shows the drama as it was recorded by the
Solar and Heliospheric Observatory
(SOHO), a joint mission of ESA and NASA.
As many
Earthlings watched in fascination,
a bright area
did emerge from closest approach, but it
soon faded and dispersed.
It is now assumed that no large fragments of
Comet C/2012 S1 (ISON) survived.
Besides the comet, the active Sun is seen to eject puffs of
plasma
known as
coronal mass ejections.
Launched in 1995,
sun-orbiting SOHO
has become a historic device in the discovery and tracking of comets known as
sungrazers.
Two months ago, a comet designated
SOHO 3000 was named in honor of the
record 3000th comet that was
discovered on SOHO images, a total that amounts to about half of all known comets.
Source - NASA
