|
|
|
Lunation
|
Lunation </b> <br>
Our Moon's appearance changes nightly.
This time-lapse sequence shows
what our Moon looks like during a
lunation, a complete lunar cycle.
As the
Moon orbits the
Earth,
the half illuminated by the
Sun
first becomes increasingly visible,
then decreasingly visible.
The Moon
always keeps the same face toward the Earth.
The Moon's apparent size changes slightly, though,
and a slight wobble called a
libration is discernible as it progresses along its elliptical orbit.
During the
cycle, sunlight reflects from the
Moon
at different angles, and so illuminates different features differently.
A full
lunation takes about 29.5 days, just under a month
(moon-th).
|
| Comet Garradd and M92 |
Comet Garradd and M92
Sweeping slowly through the constellation Hercules,
Comet Garradd (C2009/P1) passed with about 0.5 degrees of
globular
star cluster M92 on February 3.
Captured here in its latest
Messier moment, the
steady performer remains just below naked-eye
visibility
with a central coma comparable in brightness to
the dense, well-known star cluster.
The rich telescopic view from New Mexico's,
early morning skies, also features Garradd's broad
fan shaped dust tail and a much narrower ion tail that
extends up and beyond the right edge of the frame.
Pushed out by the pressure of sunlight, the dust tail
tends to trail
the comet along its orbit while
the ion tail,
blown by the solar wind, streams away from the comet in
the direction opposite the Sun.
Of course, M92 is over 25,000 light-years away.
Comet Garradd is 12.5 light-minutes
from planet Earth, arcing above
the ecliptic plane.
|
| Inside the Eagle Nebula |
Inside the Eagle Nebula
In 1995, a now famous picture
from the Hubble Space Telescope featured
Pillars of Creation, star forming columns of cold gas and
dust light-years long inside
M16, the Eagle Nebula.
This remarkable false-color
composite
image revisits the nearby stellar nursery
with image data from the orbiting
Herschel Space Observatory and
XMM-Newton
telescopes.
Herschel's far infrared
detectors record the emission from
the region's cold dust directly, including the famous pillars
and other structures
near the center of the scene.
Toward the other extreme of the
electromagnetic spectrum, XMM-Newton's
X-ray
vision reveals the massive, hot stars of
the nebula's embedded star cluster.
Hidden from Hubble's view at optical wavelengths,
the massive stars have a profound effect,
sculpting and transforming the natal gas and dust
structures with their energetic winds and radiation.
In fact, the massive stars are short lived and astronomers
have found evidence
in the image data pointing to the remnant of a supernova explosion
with an apparent age of 6,000 years.
If true, the expanding shock waves would have
destroyed the visible structures, including the famous pillars.
But because the Eagle Nebula is some 6,500 light-years distant,
their destruction won't
be witnessed for hundreds of years.
|
| La Silla Star Trails North and South |
La Silla Star Trails North and South
Fix your camera to a tripod and you can record graceful
trails
traced by the stars as planet Earth
rotates on its axis.
If the tripod is set up at ESO's
La
Silla Observatory, high in the
Atacama desert
of Chile, your star trails would look
something like this.
Spanning about 4 hours on the night of January 24,
the image is
actually a composite of 250 consecutive 1-minute exposures,
looking toward the north.
The North Celestial Pole,
at the center of the star trail
arcs, is just below the horizon in this southern hemisphere perspective.
In the foreground, the polished 15-meter diameter dish antenna of the
Swedish-ESO Submillimeter Telescope
(now decommissioned)
shows star trails toward the south by reflection.
Sweeping around the South Celestial Pole,
the distorted arcs of those stars appear underneath the
southern horizon in the focusing dish's inverted view.
Right of the dish is the dome of the observatory's 3.6 meter
telescope, home to the planet hunting
HARPS spectrograph.
|
Red Aurora Over Australia
|
Red Aurora Over Australia </b> <br>
Why would the sky glow red?
Aurora.
Last week's solar storms, emanating mostly from active
sunspot region 1402,
showered particles on the Earth that excited oxygen atoms high in the Earth's atmosphere.
As the excited element's electrons fell back to their ground state, they emitted a
red glow.
Were oxygen atoms lower in Earth's atmosphere excited,
the glow
would be predominantly green.
Pictured above, this high red aurora is visible just above the horizon last week near
Flinders,
Victoria,
Australia.
The sky that night, however, also glowed with more familiar but more distant objects, including the central disk of our Milky Way Galaxy on the left, and the neighboring
Large and
Small Magellanic Cloud galaxies on the right.
A time-lapse video
highlighting
auroras visible that night puts the picturesque scene in context.
Why the sky did not
also glow green remains unknown.
|
|
Space Views 
Your emotions get the right shape at our gift collections
