W5: Pillars of Star Formation
Image Credit:
WISE,
IRSA,
NASA;
Processing & Copyright :
Francesco Antonucci
Explanation:
How do stars form?
Images of the star forming region
W5
like those in the
infrared by NASA's Wide Field Infrared Survey Explorer (WISE) satellite
provide clear clues with indications that massive stars near the center of empty cavities are older than stars near the edges.
A likely reason for this is that the older stars in the center are actually
triggering
the formation of the younger edge stars.
The triggered
star formation
occurs when hot outflowing gas compresses cooler gas into
knots dense
enough to gravitationally contract into stars.
In the
featured
scientifically-colored infrared image,
spectacular pillars,
left slowly evaporating from the hot outflowing gas,
provide further
visual clues.
W5 is also known as
IC 1848, and
together with IC 1805
form a complex region of star formation popularly dubbed the
Heart
and
Soul Nebulas.
The
above image
highlights a part of W5 spanning about 2,000
light years that is rich in
star forming pillars.
W5 lies about 6,500 light years away toward the
constellation of
Cassiopeia.
NGC 7331 and Beyond
Image Credit &
Copyright:
Tony Hallas
Explanation:
Big, beautiful spiral galaxy
NGC 7331
is often touted as an analog to our own
Milky Way.
About 50 million light-years distant in the northern constellation
Pegasus,
NGC 7331 was recognized early on as
a spiral
nebula and is actually one of the brighter
galaxies
not included in Charles Messier's
famous
18th century catalog.
Since the galaxy's disk
is inclined to our line-of-sight, long
telescopic exposures often result in an image that evokes a strong
sense of depth.
The effect is further enhanced
in this sharp image from a small telescope
by galaxies that lie beyond the gorgeous
island universe.
The most prominent background galaxies are about one tenth the
apparent size
of NGC 7331 and so lie roughly ten times farther away.
Their close alignment on the sky with NGC 7331
occurs just by chance.
Seen through faint foreground dust clouds lingering above
the plane of Milky Way, this visual grouping of galaxies is
known as the
Deer Lick Group.
The Infrared Visible Andromeda
Image Credit:
Subaru
Telescope (NAOJ),
Hubble Space
Telescope
Mayall 4M Telescope
(KPNO, NOAO),
Digitized Sky
Survey,
Spitzer Space Telescope
Processing & Copyright:
Robert Gendler
Explanation:
This
remarkable synthetic color composite image was assembled from
archives of visible light and infrared astronomy image data.
The field of view spans the Andromeda Galaxy (M31), a massive spiral
a mere 2.5 million light-years away.
In fact, with over twice the diameter of
our own Milky Way,
Andromeda is
the largest nearby galaxy.
Andromeda's population of bright young blue stars lie along its sweeping
spiral arms, with the telltale reddish glow of star forming regions
traced in space- and ground-based
visible light data.
But
infrared data from the Spitzer
Space Telescope, also blended directly into the detailed composite's
red and green color channels, highlight
the lumpy dust lanes warmed by the young stars
as they wind ever closer to the
galaxy's core.
Otherwise invisible at optical wavelengths, the warm dust takes
on orange hues.
Two smaller companion galaxies,
M110 (below) and
M32 (above) are also included in the frame.
Geminid Fireball over Mount Balang
Image Credit:
Alvin Wu
Explanation:
This was a sky to remember.
While viewing the
Geminids meteor shower a few days ago, a bright fireball was captured over
Mt. Balang,
China with particularly picturesque surroundings.
In the foreground, a sea of light clouds slowly floated between dark mountain peaks.
In the background, the
constellation of Orion
shone brightly, with the familiar
three stars of Orion's belt visible near the image top right.
Sirius, the brightest star in the night sky,
is visible near the image center.
The
bright fireball
flashed for only a fraction of second on the lower right.
The
source of the fireball was a pebble that intersected the protective
atmosphere of Earth,
originally expelled by the Sun-orbiting asteroid-like object
3200 Phaethon
The Potsdam Gravity Potato
Image Credit:
CHAMP,
GRACE,
GFZ,
NASA,
DLR
Explanation:
Why do some places on Earth have higher gravity than others?
Sometimes the reason is unknown.
To help better understand the
Earth's surface, sensitive measurements by the orbiting satellites
GRACE and
CHAMP
were used to create a map of Earth's
gravitational field.
Since a center for studying these data is in
Potsdam,
Germany, and since
the result makes the Earth look somewhat like a potato, the resulting
geoid has been referred to as the Potsdam Gravity Potato.
High areas on
this map, colored red, indicate areas where gravity is
slightly stronger than usual, while in blue areas gravity is
slightly weaker.
Many bumps and valleys on the Potsdam Gravity Potato can be
attributed to surface features, such as the
North
Mid-Atlantic Ridge and the
Himalayan Mountains,
but others cannot, and so might relate to unusually
high or low sub-surface densities.
Maps
like this also help calibrate changes in the
Earth's surface including
variable ocean currents and the
melting of glaciers.
The above map was made in 2005, but more recent and more sensitive
gravity maps
of Earth were produced in
2011.
This Comet Lovejoy
Image Credit &
Copyright:
Damian Peach
Explanation:
Comet Lovejoy, C/2014 Q2, is framed like a cosmic Christmas tree
with starry decorations in this colorful telescopic portrait, snapped
on December 16th.
Its lovely coma is tinted green by diatomic C2 gas fluorescing in
sunlight.
Discovered in August of this year,
this
Comet Lovejoy is currently
sweeping north through the constellation Columba, heading for Lepus
south of Orion and bright enough to offer
good binocular
views.
Not its first time through the inner Solar System, this Comet Lovejoy
will pass closest to planet Earth on January 7, while
its perihelion (closest point to the Sun) will be on January 30.
Of course, planet Earth's own 2015 perihelion passage is scheduled for
January 4.
A
long period comet,
this Comet Lovejoy should return again ... in
about 8,000 years.
The Mysterious Methane of Mars
Illustration Credit:
Methane Workshop, Frascati Italy,
Villanueva et al. 2009,
ESA Medialab,
NASA
Explanation:
What's creating methane on Mars?
Recent measurements from the robotic
Curiosity rover
currently rolling across Mars indicate a
surprising 10-fold increase in atmospheric
methane
between measurements only months apart.
Life is a major
producer of methane on Earth, and so speculation is rampant that some sort of
life --
possibly microbial life -- is creating
methane beneath the surface of Mars.
Other possibilities do exist, though, with a leading model being the sudden release of
methane
produced by the mixing of specific soil chemicals with underground water.
Proposed origins of Martian methane are depicted in the
featured illustration.
The origin of Mars' methane is a very active area of research,
with missions like
Curiosity and India's
Mars Orbiter Mission searching for clues by measuring methane abundance changes and possible byproducts of different methane-producing processes.
The Cliffs of Comet Churyumov–Gerasimenko
Image Credit &
Licence (CC BY-SA 3.0 IGO):
ESA,
Rosetta spacecraft,
NAVCAM;
Additional Processing:
Stuart Atkinson
Explanation:
These high cliffs occur on the surface of a comet.
They were discovered to be part of the dark nucleus of
Comet Churyumov–Gerasimenko (CG) by
Rosetta,
a robotic spacecraft
launched by
ESA which began orbiting the comet in early August.
The ragged cliffs, as
featured
here, were imaged by Rosetta about two weeks ago.
Although towering about one kilometer high, the low surface gravity of
Comet CG would likely make a
jump from the
cliffs, by a human, survivable.
At the foot of the cliffs is relatively smooth terrain dotted with
boulders as large as 20 meters across.
Data from Rosetta indicates that the ice in Comet CG has a significantly different deuterium fraction -- and hence likely a
different origin -- than the water in Earth's oceans.
The
Rosetta spacecraft is scheduled to
continue to accompany the comet as it makes its closest approach to the Sun in 2015 August.
IC 1795: The Fishhead Nebula
Image Credit &
Copyright:
Bill Snyder
(Bill
Snyder Photography)
Explanation:
To some, this nebula looks like the
head of a fish.
However,
this colorful cosmic portrait really features
glowing gas
and obscuring dust clouds in IC 1795,
a star forming region in the northern constellation Cassiopeia.
The nebula's colors were created by adopting the
Hubble false-color palette
for mapping narrow emission from oxygen, hydrogen,
and sulfur atoms to blue, green and red colors, and further
blending the data with images of the region recorded through
broadband filters.
Not far on the sky from the famous
Double Star
Cluster in Perseus, IC 1795 is itself located next to IC 1805,
the
Heart Nebula, as part of a
complex
of star forming regions that lie
at the edge of a large molecular cloud.
Located just over 6,000
light-years away, the larger
star forming complex sprawls along the Perseus spiral arm of
our
Milky Way Galaxy.
At that distance, this picture would span about 70 light-years
across IC 1795.
Source -
NASA
