Every galaxy resides at the center of an enormous bubble of dark matter several times larger in diameter and many times greater in mass. Dwarf galaxies, the small cosmic Lego bricks that combined to form the galaxies we witness today, contain greater proportions of dark matter than large spirals. As a result, dwarf galaxies give astronomers a better opportunity to study dark matter and its effects.
In this image taken on Jan. 25, 2012, the Aurora Borealis steals the scene in this nighttime photograph shot from the International Space Station as the orbital outpost flew over the Midwest. The spacecraft was above south central Nebraska when the photo was taken. The image, taken at an oblique angle, looks north to northeast.
Image Credit: NASA
NGC 5965 and NGC 5963 in Draco
Distance: NGC 5965, 150 million light-years. NGC 5963, 40 million light-years
These two spiral galaxies make a photogenic pair, found within the boundaries of the northern constellation Draco. Contrasting in color and orientation, NGC 5965 is nearly edge-on to our line of sight and dominated by yellow hues, while bluish NGC 5963 is closer to face-on.
Image Credit & Copyright: Stephen Leshin
Enceladus Backlit by Saturn
(This is a real picture)
The above image was taken last year by the robotic Cassini spacecraft during a close pass by by the enigmatic moon. Inspection of the lower part of this digitally sharpened image reveals plumes of ice crystals thought to originate in a below-surface sea
Image Credit: Cassini Imaging Team, SSI, JPL, ESA, NASA; Color Composite: Gordan Ugarkovic
Lunation
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
Image Credit & Copyright: Myself
NGC281, Emission Nebula and Open Cluster in Cassiopeia
Distance 9600 light years
The complex is located in the Perseus arm of our galaxy and its visible structure spans some 60 light years. The molecular cloud counterpart has been busy in the last few million years forming the massive young stars of the central cluster IC 1590.
IC 1590 is the source of ionization for the visible nebula and an excellent example of a very young cluster where pre-main sequence stars can be found in abundance, indicating active and ongoing star formation.
NGC 7635, The Bubble Nebula in Cassiopeia
Image Acquisition: Michael Joner and David Laney (BYU)
Image Processing: Robert Gendler