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
Explanation: Double,
double toil and trouble;
Fire burn, and cauldron bubble .... maybe Macbeth
should have consulted the Witch Head Nebula.
A frighteningly shaped
reflection nebula, this
cosmic crone is about 800 light-years away though.
Its malevolent visage seems to glare toward
nearby bright star Rigel in Orion,
just off the right edge of this frame.
More formally known as
IC 2118,
the interstellar cloud of dust and gas is nearly 70 light-years across,
its dust grains reflecting Rigel's starlight.
In this
composite portrait, the nebula's color
is caused not only by the star's intense bluish light but because the
dust grains
scatter blue light more efficiently than red.
The same physical process causes
Earth's daytime sky to appear blue,
although the scatterers in
planet Earth's atmosphere are molecules of nitrogen and oxygen.
Explanation: This
cosmic close-up looks deep inside the Soul Nebula.
The dark and brooding dust clouds outlined by bright
ridges of glowing gas are cataloged as IC 1871.
About 25 light-years across,
the telescopic field of view spans only
a small part of the much larger
Heart and Soul nebulae.
At an estimated distance of 6,500 light-years the star-forming
complex lies within the Perseus spiral arm
of the Milky Way, seen in planet
Earth's skies toward the constellation Cassiopeia.
An example of
triggered star formation,
the dense star-forming clouds of IC 1871 are themselves
sculpted by the intense winds and radiation of the region's
massive young stars.
This color image adopts a
palette made popular in Hubble images
of star-forming regions.
Explanation:
What happens when a star gets too close to a black hole?
Recent observations from Earth-orbiting observatories of an event dubbed
ASASSN-14li,
in a distant galactic center,
appears to be giving one star's harrowing story.
Although angularly unresolved,
variations in high energy light
indicate that some of the star became
shredded and reformed into a
disk swirling
around the dark abyss.
In the hypothesized
scenarioenvisioned,
a jet formed on the spin axis of the black hole.
The innermost part of the disk, colored white, glows most strongly in
X-rays
and may drive a periodic
wind, shown in blue.
Future X-ray and ultraviolet observations of stellar disruptions by
black holes -- including those in the
center of our own galaxy --
hold promise of telling us about the
complex dynamics
of some of the hottest and highest-gravity places in the universe.
right from the Heart Nebula Image Copyright: Simon Addis
Explanation:
What's that inside the Heart Nebula?
First, the large emission nebula dubbed
IC 1805 looks, in whole, like a human heart.
The nebula glows brightly in red light
emitted by its most prominent element:
hydrogen.
The red glow and the larger shape are all created by a
small group of stars near the
nebula's center.
In the center of the Heart Nebula are young stars from the open star cluster
Melotte 15 that are eroding away several picturesque
dust pillars with their energetic light and winds.
The open cluster of stars contains a few
bright stars nearly 50 times the mass of our Sun,
many dim stars only a fraction of the mass of our Sun, and an
absent microquasar
that was expelled millions of years ago.
The Heart Nebula is located about 7,500 light years away toward the
constellation
of Cassiopeia.
At the top right is the companion
Fishhead Nebula
Explanation: Two
remarkable global maps
of Jupiter's banded cloud tops
can be compared by just sliding your cursor
over this sharp projection
(or follow this link) of image data from the Hubble Space Telescope.
Both captured on January 19, during
back-to-back 10 hour rotations of the ruling gas giant, the
all-planet projections represent the first in
a series of planned annual portraits by the
Outer
Planet Atmospheres Legacy program.
Comparing the two highlights cloud movements and
measures wind speeds in the planet's
dynamic atmosphere.
In fact,
the Great Red Spot,
the famous long-lived
swirling storm boasting
300 mile per hour winds, is seen sporting a rotating, twisting filament.
The images confirm that Great Red Spot is
still
shrinking, though still larger than planet Earth.
Posing next to it (lower right)
is Oval BA, also known as
Red Spot Junior.
Explanation:
The north pole of Saturn's moon
Enceladus
is unexpectedly fascinating and complex.
Previous to the
latest flyby of the
robotic Cassini spacecraft,
the northern region was known mostly for its unusually high
abundance of craters.
Last week's flyby, however, returned images of unprecedented detail, including the
featured image
showing the expected craters coupled with an
unexpected and circuitous pattern of picturesque cracks and fractures.
Broken terrain has been recorded at lower latitudes, with deep canyons dubbed
Tiger Stripes near Enceladus' South Pole.
The fractures may further indicate global interplay between the surface and potential
seas underneath, seas that
future missions might target for
signs of life.
Explanation:
What happens when two black holes collide?
This extreme scenario likely occurs in the centers of some merging galaxies and multiple star systems.
The featured video
shows a computer animation of the final stages of such a merger, while highlighting the
gravitational lensing
effects that would appear on a background
starfield.
The black regions indicate the
event horizons of the
dynamic duo,
while a surrounding ring of shifting background stars indicates the position of their combined
Einstein ring.
All background stars not only have
images visible outside of this
Einstein ring,
but also have one or more companion images visible on the inside.
Eventually the two black holes
coalesce.
The end stages of such a merger may provide a strong and predictable blast of
gravitational radiation,
a much sought after form of radiation
different than light that has never yet been directly observed.
Explanation:
Like an illustration in a galactic
Just So Story,
the Elephant's Trunk Nebula
winds through the emission nebula and young star cluster
complex IC 1396, in the high and far off
constellation of Cepheus.
Of course, the cosmic
elephant's trunk is over 20 light-years long.
This composite
was recorded through
narrow band filters
that transmit the light from ionized hydrogen, sulfur,
and oxygen
atoms in the region.
The resulting image highlights the bright
swept-back ridges
that outline pockets of cool
interstellar
dust and gas.
Such embedded, dark,
tendril-shaped clouds contain the
raw material for
star formation and hide
protostars within the obscuring cosmic dust.
Nearly 3,000
light-years
distant, the relatively faint
IC
1396 complex covers a large region on the sky, spanning over 5 degrees.
Explanation:
Clouds of glowing gas mingle with dust lanes in the
Trifid Nebula, a star forming region toward the constellation of the Archer (Sagittarius).
In the center, the three prominent
dust lanes that give the
Trifid its name all come together.
Mountains of opaque dust
appear on the right, while other dark filaments of
dust are visible threaded throughout the nebula.
A single massive star
visible near the center causes much of the
Trifid's glow.
The Trifid, also known as
M20,
is only about 300,000 years old, making it among the youngest
emission nebulae known.
The nebula
lies about 9,000
light years away and the part
pictured here spans about 10 light years.
The above image is a composite with
luminance taken from an image by the 8.2-m ground-based
Subaru Telescope,
detail provided by the 2.4-m orbiting
Hubble Space Telescope,
color data provided by
Martin Pugh
and image assembly and processing provided by
Robert Gendler.
