Portal:Astronomy/Picture/August 2005

Featured pictures on the Astronomy Wikiportal, August 2005

1 August 2005 ()	2 August 2005 ()
Johannes Hevelius drew the Orion constellation in Uranographia, his celestial catalogue in 1690. The view is mirrored to match the view through a telescope.	The open cluster Messier 11 The above pictured open cluster, M11, is visible with binoculars towards the constellation of Scutum and contains thousands of stars and is just over five thousand light years distant. The stars in this cluster all formed together about 250 million years ago. The bright young stars in M11 appear blue.
3 August 2005 ()	4 August 2005 ()
Solar System Presentation of the Solar System (not to scale). The Solar System consists of the Sun and all the objects that orbit around it, including meteors, asteroids, comets, moons, and planets.	Ida and Dactyl During its examination of the asteroid Ida, the Galileo spacecraft returned images of a second object, Dactyl--the first confirmed satellite or moon of an asteroid; the much smaller moon is visible to the right of Ida.
5 August 2005 ()	6 August 2005 ()
Artist's View of Black Hole and Companion Star GRO J1655-40 An accretion disc is a structure formed by material falling into a gravitational source. Conservation of angular momentum requires that, as a large cloud of material collapses inward, any small rotation it may have will increase. Centrifugal force causes the rotating cloud to collapse into a disc, and tidal effects will tend to align this disc's rotation with the rotation of the gravitational source in the middle.
7 August 2005 ()	8 August 2005 ()
	Cigar galaxy, complements of NASA The Cigar Galaxy is an irregular galaxy 12 million light years away. It can also be called M82 or NGC 3034. The galaxy is a starburst galaxy in the Ursa Minor constellation. This image was obtained as part of the Two Micron All Sky Survey.
9 August 2005 ()	10 August 2005 ()
	The Ant planetary nebula (Mz3) is shown here ejecting gas from the dying center star, which displays symmetrical patterns unlike the chaotic patterns of ordinary explosions. This is explained by either the gravitational pull of another object, or winding of the expelled matter and magnetic fields. Mz3 is often referred to as the Ant Nebula because it resembles the head and thorax of a garden-variety ant.
11 August 2005 ()	12 August 2005 ()
The Crab Pulsar (PSR B0531+21) is a supernova remnant located in the Crab Nebula. The pulsar is roughly 10 kilometers in diameter and rotates once every 33 milliseconds, or 30 times each second, emitting x-rays as it does. The image shows x-ray emissions gathered by the Chandra X-ray Observatory in blue, and optical ones from the Hubble Space Telescope in red.	The Pinwheel Galaxy, or M101, was discovered by Pierre Méchain, on March 27, 1781, and is located between 23,790,000 or 27,000,000 light years from Earth. It is the brightest galaxy in the M101 group of galaxies, with an apparent magnitude of +7.9 and an absolute magnitude of -21.6. The Pinwheel galaxy can be found in the Ursa Major constellation, and the M101 group of galaxies. This picture was taken and released by an amateur astronomer.
13 August 2005 ()	14 August 2005 ()
This optical afterglow of gamma-ray burst GRB 990123 was taken in 1999 by the NASA Hubble Space Telescope. Gamma-ray bursts (GRBs) are the most luminous physical phenomena that can currently be seen from Earth. They emmit gamma rays for a short period of time (anywhere from seconds to hours), then X-rays for several days afterwards. Though their cause is unknown, it is widely specualted that they arise from a hypernova, where a large star collapses into a black hole, and large amounts of energy and matter are exerted.	The Wilkinson Microwave Anisotropy Probe is a satellite owned by NASA that measures leftover energy from the Big Bang. This photo is an image measuring anisotropies in the cosmic microwave background radiation, which could be considered the cooled remnants of the big bang. The CMB gives a snapshot of the universe when, according to standard cosmology, the temperature dropped enough to allow electrons and protons to form hydrogen atoms, thus making the universe transparent to radiation, and leaving only loose electron microwaves as background radiation. Before this point, highly energetic matter and radiation was simply absorbed and expelled in a process known as Compton scattering.
15 August 2005 ()	16 August 2005 ()
Nebula NGC 604 is an H II region inside the Triangulum Galaxy. It was discovered by William Herschel in 1784. The glow of the nebula is because it is an emission nebula, so unlike a reflection nebulae, where light from neighboring stars reflect off it, or dark nebulae, which are completely unilluminated, NGC 604 is lit by stars being formed inside it. The stars, that form from the compaction and heating of dust and gas due to gravity, ionize the gas of the nebula, causing it to emit light.	File:NGC6543 concentric rings.jpg The Cat's Eye Nebula, or NGC 6543, is a planetary nebula in the Draco constellation. It has a relatively high apparent magnitude of +8.1, and the central star of the nebula is approximately 10,000 times the luminosity of our sun. NGC 6543 is located 3,600 light years from the Earth. It is expanding, and unexplainedly ejecting the concentric rings shown in the picture every few hundred years.
17 August 2005 ()	18 August 2005 ()
The Cigar Galaxy, also called M82, or NGC 3034, is a starburst galaxy in the Ursa Major constellation, photographed here by the Chandra X-ray Observatory. It is debated on whether the galaxy is an irregular galaxy because of its seemingly unorderly structure. or whether its structure is simply concealed to us from massive amounts of dust, and it is really a barred spiral galaxy, with its spiral arms and orderly rows of stars being hidden by large amounts of dust and gravitational distortion.	The Orbiting Astronomical Observatory satellites were a series of four space observatories launched by NASA between 1966 and 1972. The OAO program demonstrated the viability of space-based observatories and paved the way for the development of the Hubble Space Telescope. This image shows OAO-3 being prepared for launch in a clean room.
19 August 2005 ()	20 August 2005 ()
21 August 2005 ()	22 August 2005 ()
	Olympus Mons is the largest volcano in the Solar System, rising some 27 km above the Tharsis plain on Mars. At its summit is a complex caldera about 80 km across, consisting of several nested craters formed when the top of the mountain collapsed into empty magma chambers after giant eruptions.
23 August 2005 ()	24 August 2005 ()
Lyman Spitzer was one of the first astronomers to discuss the potential advantages of space telescopes over ground-based telescopes, and was one of the key figures in the development of the Hubble Space Telescope, as well as publishing many key papers in the study of the interstellar medium and ionised nebulae. The Spitzer Space Telescope is named after him.	Noctilucent clouds are bright cloud-like phenomena, typically seen in late twilight on summer nights at mid-northern and mid-southern latitudes. They form at altitudes of about 85 kilometres, and therefore reflect the Sun's light long after it has set. Formerly infrequently seen, they have become increasingly common over the last century, for reasons which have yet to be established.
25 August 2005 ()	26 August 2005 ()
	Numerous faint and distant galaxies are visible in these extracts from the Hubble Deep Field, which is one of the deepest images ever taken of the distant universe and was a landmark in observational cosmology when it was created in 1995.
27 August 2005 ()	28 August 2005 ()
29 August 2005 ()	30 August 2005 ()
	The Hubble Space Telescope's main mirror was accidentally ground incorrectly, resulting in a spherical aberration which severely degraded the image quality obtainable with the telescope. Space Shuttle mission STS-61 installed corrective optics on the telescope, the effect of which can be seen in these 'before and after' images of the spiral galaxy M100
31 August 2005 ()