Spiral Galaxy M77
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Поделиться222013-09-28 12:19:48
Barred Spiral Galaxy NGC 2903
Поделиться232013-09-28 12:20:43
Nebula NGC 2170
This enigmatic region in the constellation of Monoceros displays a wonderful mix of nebula types. The bluish areas are reflection nebulas, so-named because they reflect the light of nearby stars. The dust particle size in these areas preferentially reflects blue light, similar to cigarette and other kinds of smoke. The red areas are emission nebulas, and shine by a different mechanism. Ultraviolet light from nearby stars excites hydrogren and other gas atoms in the nebula, which then emit light of their own in specific colors. Finally, what looks a bit like black ink spilled across the image constitutes a dark nebula, and is only seen because of the light that it blocks. In other words, the dark nebula is seen in silhouette.
Поделиться242013-09-28 12:22:22
The Pelican Nebula
in Mapped Color
This is a portion of the Pelican Nebula, in the constellation of Cygnus, the Swan. The "mountains" in this image are formed by an area of denser gas and dust that is slowly being eroded away by the ultraviolet radiation from nearby young, hot stars, forming what is known as an ionization front. By using special filters to isolate the light from individual chemical elements, and assigning these elements to different colors, subtle variations in the energy levels within the cloud can be brought into stark detail. Light from oxygen atoms is shown as blue, and represents the highest energy. Red represents sulphur, and details the areas of lowest energy level, right at the boundary that is the ionization front. The light from hydrogen atoms is used for the green channel and represents an intermediate energy level.
Поделиться252013-09-28 12:25:16
The Lagoon Nebula
in Mapped Color
Поделиться262013-09-28 12:26:42
The Hercules Galaxy Cluster
It's couple's night in the celestial zoo! While there are a few wallflowers among the myriad members of the Hercules Galaxy cluster, many are involved in intricate and chaotic dances with nearby companions. This is quite common in galaxy clusters. Close galaxies orbit one another, distort each other's shape, and eventually merge into a single galaxy. In fact, this seems to have already occured in at least one case in this area. Notice the galaxy just to the right of bottom-center. Known as IC 1182, it is surrounded by wispy structures known as tidal tails, and a blue jet extends to the right from its nucleus, all evidence that this dancer has recently devoured its partner.
Поделиться272013-09-28 12:27:50
The Leo I Dwarf Galaxy
Located only a third of a degree away from one of the brightest stars in the sky we find a celestial oddball. Leo I is a dwarf spheroidal galaxy, so named for its small size and oblong shape. At a distance of 900,000 light years, it is thought to be the furthest of the Milky Way's satellite galaxies (i.e., it is in orbit around our galaxy).
The exceedingly bright star in the upper left is Regulus, the brightest star in the constellation Leo. It is actually a triple star system. Both companion stars are visible in this photograph. Locate the two somewhat orange stars to the upper-right of Regulus. This system lies at a distance of about 77.5 light years from Earth. Regulus is much more massive than the sun, and is thus much hotter, giving it its bluish color.
Поделиться282013-09-28 12:32:38
The Colors of the Moon
Is the moon really this colorful? In a way, yes. The lunar surface actually does have quite a bit of color, although in reality it is very subtle. In this photograph, the color saturation has been enhanced to bring out the differences in the colors of the various areas of the surface. The hues are correct, just much more vivid than we usually see them.
Aside from making an interesting aesthetic presentation, the colors also give clues as to the mineralogy of the moon's surface. Also, at the sites of many impact craters we can see that deeper material exposed (and in some cases scattered) by the impact is of a different composition than the material on the surface.
Поделиться292013-09-28 12:34:52
The Great Orion Nebula
in Mapped Color
The Great Orion Nebula is a vast region of intense star formation. Massive, hot young stars — destined to lead short lives due to the rate at which they are consuming their hydrogen fuel — are the illuminating sources for the clouds of gas and dust that we see. Their intense ultraviolet light excites individual atoms in the nebula, causing them to fluoresce: each chemical element re-emits light in its own specific color.
In this image, special filters were used to isolate the light from three of these elements, and these exposures were then combined to form a color composite: red for sulphur, green for hydrogen, and blue for oxygen. In reality, both sulphur and hydrogen emit a deep red color, while oxygen emits a teal hue. The "mapped" color assignment in this image highlights the distribution of energized atoms in the nebula.
Поделиться302013-09-28 12:37:05
The Pelican Nebula
in Mapped Color
This is a portion of the Pelican Nebula, in the constellation of Cygnus, the Swan. The "mountains" in this image are formed by an area of denser gas and dust that is slowly being eroded away by the ultraviolet radiation from nearby young, hot stars, forming what is known as an ionization front. By using special filters to isolate the light from individual chemical elements, and assigning these elements to different colors, subtle variations in the energy levels within the cloud can be brought into stark detail. Light from oxygen atoms is shown as blue, and represents the highest energy. Red represents sulphur, and details the areas of lowest energy level, right at the boundary that is the ionization front. The light from hydrogen atoms is used for the green channel and represents an intermediate energy level.