NASA Astronomy Picture of the Day

[frogfish]

Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2006 May 22

Maneuvering in Space

Credit: STS-114 Crew, ISS Expedition 11 Crew, NASA

Explanation: What arm is 17 meters long and sometimes uses humans for fingers? The Canadarm2 aboard the International Space Station (ISS). Canadarm2 has multiple joints and is capable of maneuvering payloads as massive as 116,000 kilograms, equivalent to a fully loaded bus. Canadarm2 is operated by remote control by a human inside the space station. To help with tasks requiring a particularly high level of precision and detail, an astronaut can be anchored to an attached foot constraint. The arm is able propel itself end-over-end around the outside of the space station. Pictured above, astronaut Stephen Robinson rides Canadarm2 during the STS-114 mission of the space shuttle Discovery to the ISS in 2005 August. Space shuttles often deploy their own original version of a robotic arm dubbed Canadarm. Next year, a second robotic arm is scheduled to be deployed on the space station.

[00000000000000000000000000]

Astronomy Picture of the Day Archive: APOD Archive

It goes back to June 16 1995

Thanks zandore.

Nice pictures and all, but couldn't we all just go to the APOD website rather than having a thread about it where the posts are just copy-pasted?

Edited May 22, 2006 by angrycrustacean

[Waspie_Dwarf]

Nice pictures and all, but couldn't we all just go to the APOD website rather than having a thread about it where the posts are just copy-pasted?

The beauty of free will is that you are quite free to follow the link if that is what you want to do, alternatively those who would rather come to this thread are also free to do so.

[kaknelson]

Planetary Nebula NGC 6369: The Little Ghost

An Old Star Gives Up the Ghost

NASA's Hubble Space Telescope has recently obtained images of the planetary nebula NGC 6369. This object is known to amateur astronomers as the "Little Ghost Nebula," because it appears as a small, ghostly cloud surrounding the faint, dying central star. NGC 6369 lies in the direction of the constellation Ophiuchus, at a distance estimated to be between about 2,000 and 5,000 light-years from Earth.

When a star with a mass similar to that of our own Sun nears the end of its lifetime, it expands in size to become a red giant. The red-giant stage ends when the star expels its outer layers into space, producing a faintly glowing nebula. Astronomers call such an object a planetary nebula, because its round shape resembles that of a planet when viewed with a small telescope.

The Hubble photograph of NGC 6369, captured with the Wide Field Planetary Camera 2 (WFPC2) in February 2002, reveals remarkable details of the ejection process that are not visible from ground-based telescopes because of the blurring produced by the Earth's atmosphere.

The remnant stellar core in the center is now sending out a flood of ultraviolet (UV) light into the surrounding gas. The prominent blue-green ring, nearly a light-year in diameter, marks the location where the energetic UV light has stripped electrons off of atoms in the gas. This process is called ionization. In the redder gas at larger distances from the star, where the UV light is less intense, the ionization process is less advanced. Even farther outside the main body of the nebula, one can see fainter wisps of gas that were lost from the star at the beginning of the ejection process.

The color image has been produced by combining WFPC2 pictures taken through filters that isolate light emitted by three different chemical elements with different degrees of ionization. The doughnut-shaped blue-green ring represents light from ionized oxygen atoms that have lost two electrons (blue) and from hydrogen atoms that have lost their single electrons (green). Red marks emission from nitrogen atoms that have lost only one electron. Our own Sun may eject a similar nebula, but not for another 5 billion years.

The gas will expand away from the star at about 15 miles per second, dissipating into interstellar space after some 10,000 years. After that, the remnant stellar ember in the center will gradually cool off for billions of years as a tiny white dwarf star, and eventually wink out.

Edited May 23, 2006 by Kaknelson

[frogfish]

Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2006 May 23

Comet Schwassmann-Wachmann 3 Passes the Earth

Credit & Copyright: Thad V'Soske (Cosmotions.com)

Explanation: Rarely does a comet pass this close to Earth. Last week, dedicated astrofilmographers were able to take advantage of the close approach of crumbling 73P / Comet Schwassmann-Wachmann 3 to make time-lapse movies of the fast-moving comet. Large comet fragments passed about 25 times the Moon's distance from the Earth. The above time lapse movie of Fragment B of Comet Schwassmann-Wachmann 3 over Colorado, USA was taken during a single night, May 16, with 83 consecutive 49-second exposures. Some observers report being able to perceive the slight motion of the comet with respect to the background stars using only their binoculars and without resorting to the creation of fancy digital time-lapse movies. Fragment B of Comet Schwassmann-Wachmann 3 became just barely visible to the unaided eye two weeks ago but now is appearing to fade as the comet has moved past the Earth and nears the Sun. Many sky enthusiasts will be on the watch for a particularly active meteor shower tonight as the Earth made its closest approach to orbit of Comet Schwassmann-Wachmann 3 late yesterday.

[kaknelson]

Our Galaxy! ( i dunno how they know what it looks like! )

The Milky Way, it turns out, is no ordinary spiral galaxy. According to a massive new survey of stars at the heart of the galaxy by Wisconsin astronomers, including professor of astonomy Edward Churchwell and professor of physics Robert Benjamin, the Milky Way has a definitive bar feature -- some 27,000 light years in length -- that distinguishes it from pedestrian spiral galaxies, as shown in this artist's rendering. The survey, conducted using NASA's Spitzer Space Telescope, sampled light from an estimated 30 million stars in the plane of the galaxy in an effort to build a detailed portrait of the inner regions of the Milky Way.

Image credit: courtesy NASA/JPL-Caltech/R. Hurt (SSC/Caltech)

Photo date: 2005

[frogfish]

Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2006 May 24

A Five Quasar Gravitational Lens

Credit: K. Sharon (Tel Aviv U.) and E. Ofek (Caltech), ESA, NASA

Explanation: What's happening near the center of this cluster of galaxies? At first glance, it appears that several strangely elongated galaxies and fully five bright quasars exist there. In reality, an entire cluster of galaxies is acting as a gigantic gravitational lens that distorts and multiply-images bright objects that occur far in the distance. The five bright white points near the cluster center are actually images of a single distant quasar. This Hubble Space Telescope image is so detailed that even the host galaxy surrounding the quasar is visible. Close inspection of the above image will reveal that the arced galaxies at 2 and 4 o'clock are actually gravitationally lensed images of the same galaxy. A third image of that galaxy can be found at about 10 o'clock from the cluster center. Serendipitously, numerous strange and distant galaxies dot the above image like colorful jewels. The cluster of galaxy that acts as the huge gravitational lens is cataloged as SDSS J1004+4112 and lies about 7 billion light years distant toward the constellation of Leo Minor.

[kaknelson]

Nebulas Surrounding Wolf-Rayet Binary BAT99-49

Credit & Copyright: Y. Naze, G. Rauw, J. Manfroid, J. Vreux (Univ. Liege), Y. Chu (Univ. Illinois), ESO

How could two young stars power these colorful interstellar gas clouds? Although hidden by thick dust, the stars spew forceful ions and energetic radiation that cause the clouds to fragment and light up. The above composite color image from the European Southern Observatory's Melipal VLT telescope resolves details in the nebula complex known as BAT99-49, with emission from helium atoms in blue hues, oxygen atoms in green, and hydrogen atoms in red. Located in the Large Magellanic Cloud (LMC), the largest satellite galaxy to our own Milky Way Galaxy, one of the stars in the central binary is an enigmatic Wolf-Rayet star while the other is a massive O star. Wolf-Rayet stars have some of the hottest surfaces in the universe, while O stars are the most massive and energetic of normal main sequence stars.

[MID]

Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2006 May 22

Can you imagine anything that would be more fun that what this fellow is doing?

[Lilly]

Well, MID, I must admit that's one great picture...but fun? No, that wouldn't be much fun for me. You see, I'm afraid of heights! The thought of doing something like that really freaks me out.

[frogfish]

Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2006 May 27

Gamma-Ray Moon

Credit: Dave Thompson (NASA/GSFC) et al., EGRET, Compton Observatory, NASA

Explanation: If you could see gamma rays - photons with a million or more times the energy of visible light - the Moon would appear brighter than the Sun! The startling notion is demonstrated by this image of the Moon from the Energetic Gamma Ray Experiment Telescope (EGRET) in orbit on NASA's Compton Gamma Ray Observatory from April 1991 to June 2000. Then, the most sensitive instrument of its kind, even EGRET could not see the quiet Sun which is extremely faint at gamma-ray energies. So why is the Moon bright? High energy charged particles, known as cosmic rays, constantly bombard the unprotected lunar surface generating gamma-ray photons. EGRET's gamma-ray vision was not sharp enough to resolve a lunar disk or any surface features, but its sensitivity reveals the induced gamma-ray moonglow. So far unique, the image was generated from eight exposures made during 1991-1994 and covers a roughly 40 degree wide field of view with gamma-ray intensity represented in false color.

[kaknelson]

Vancouver from Space.

Credits: ESA

Vancouver (pronounced [væːnˈkʰuv̥ɚ]) is a Canadian city in the province of British Columbia. It is the largest metropolitan centre in western Canada and the third largest in the country. Vancouver is one of the cities of the Greater Vancouver Regional District (GVRD) and of the larger geographic region commonly known as the Lower Mainland of B.C. The Port of Vancouver is significant on a world scale, and Vancouver is the third largest film production centre for US-based productions in North America after Hollywood and New York.

The city's population is 545,671 and that of the metropolitan area 2,186,965 (2001 census).[1] Some predict that by 2020, the population of the metropolitan area will be 2.6 million.[2] A resident of Vancouver is called a "Vancouverite." The current mayor is Sam Sullivan.

Vancouver will be the host city for the 2010 Winter Olympics, the 2006 United Nations World Urban Forum , the 2007 Memorial Cupand the 2009 World Police and Fire Games. Vancouver will host some games for the 2007 FIFA U20 World Cup.

[frogfish]

Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2006 May 28

GRO J1655-40: Evidence for a Spinning Black Hole

Drawing Credit: A. Hobart, CXC

Explanation: In the center of a swirling whirlpool of hot gas is likely a beast that has never been seen directly: a black hole. Studies of the bright light emitted by the swirling gas frequently indicate not only that a black hole is present, but also likely attributes. The gas surrounding GRO J1655-40, for example, has been found to display an unusual flickering at a rate of 450 times a second. Given a previous mass estimate for the central object of seven times the mass of our Sun, the rate of the fast flickering can be explained by a black hole that is rotating very rapidly. What physical mechanisms actually cause the flickering -- and a slower quasi-periodic oscillation (QPO) -- in accretion disks surrounding black holes and neutron stars remains a topic of much research.

[Beggars]

dear god,that things freaky lookin,i don't wanna go into space anymore

[frogfish]

Amazing place space is, eh?

[Master Sage]

Vancouver from Space.

Credits: ESA

Vancouver (pronounced [væːnˈkʰuv̥ɚ]) is a Canadian city in the province of British Columbia. It is the largest metropolitan centre in western Canada and the third largest in the country. Vancouver is one of the cities of the Greater Vancouver Regional District (GVRD) and of the larger geographic region commonly known as the Lower Mainland of B.C. The Port of Vancouver is significant on a world scale, and Vancouver is the third largest film production centre for US-based productions in North America after Hollywood and New York.

The city's population is 545,671 and that of the metropolitan area 2,186,965 (2001 census).[1] Some predict that by 2020, the population of the metropolitan area will be 2.6 million.[2] A resident of Vancouver is called a "Vancouverite." The current mayor is Sam Sullivan.

Vancouver will be the host city for the 2010 Winter Olympics, the 2006 United Nations World Urban Forum , the 2007 Memorial Cupand the 2009 World Police and Fire Games. Vancouver will host some games for the 2007 FIFA U20 World Cup.

Nice, that is sweet!

[kaknelson]

Thanks, ^^^^...... that's my city

NGC 6960: The Witch's Broom Nebula

Credit & Copyright: T. A. Rector (U. Alaska), WIYN, NOAO, AURA, NSF

Ten thousand years ago, before the dawn of recorded human history, a new light must suddenly have appeared in the night sky and faded after a few weeks. Today we know this light was an exploding star and record the colorful expanding cloud as the Veil Nebula. Pictured above is the west end of the Veil Nebula known technically as NGC 6960 but less formally as the Witch's Broom Nebula. The rampaging gas gains its colors by impacting and exciting existing nearby gas. The supernova remnant lies about 1400 light-years away towards the constellation of Cygnus. This Witch's Broom actually spans over three times the angular size of the full Moon. The bright star 52 Cygnus is visible with the unaided eye from a dark location but unrelated to the ancient supernova.

[frogfish]

Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2006 May 30

Ancient Craters on Saturn's Rhea

Credit: Cassini Imaging Team, SSI, JPL, ESA, NASA

Explanation: Saturn's ragged moon Rhea has one of the oldest surfaces known. Estimated as changing little in the past billion years, Rhea shows craters so old they no longer appear round – their edges have become compromised by more recent cratering. Like Earth's Moon, Rhea's rotation is locked on Saturn, and the above image shows part of Rhea's surface that always faces Saturn. Rhea's leading surface is more highly cratered than its trailing surface. Rhea is composed mostly of water-ice but is thought to have a small rocky core. The above image was taken by the robot Cassini spacecraft now orbiting Saturn. Cassini swooped past Rhea two months ago and captured the above image from about 100,000 kilometers away. Rhea spans 1,500 kilometers making it Saturn's second largest moon after Titan. Several surface features on Rhea remain unexplained including large light patches.

[kaknelson]

The Planetary Nebula NGC 7207

Credit: H. Bond (STScI) and NASA, From the Hubble Space Telescope.

This NASA Hubble Space Telescope image of planetary nebula NGC 7027 shows remarkable details of the process by which a star like the Sun dies. New features include: faint, blue, concentric shells surrounding the nebula; an extensive network of red dust clouds throughout the bright inner region; and the hot central white dwarf, visible as a white dot at the center. The nebula is a record of the star's final death throes. Initially the ejection of the star's outer layers, when it was at its red giant stage of evolution, occurred at a low rate and was spherical. The initial ejections occurred episodically to produce the concentric shells. This culminated in a vigorous ejection of all of the remaining outer layers, which produced the bright inner regions. At this later stage the ejection was non-spherical, and dense clouds of dust condensed from the ejected material.

NGC 7027 is located about 3,000 light-years from Earth in the direction of the constellation Cygnus. When a star like the Sun nears the end of its life, it expands to more than 50 times its original diameter, becoming a red giant star. Then its outer layers are ejected into space, exposing the small, extremely hot core of the star, which cools off to become a white dwarf. Although stars like the Sun can live for up to 10 billion years before becoming a red giant and ejecting a nebula, the actual ejection process takes only a few thousand years. The NGC 7027 photograph is a composite of two Hubble images, taken in visible and infrared light, and is shown in "pseudo-color."

[frogfish]

Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2006 June 2

IC 443: Supernova Remnant and Neutron Star

Credit: Chandra X-ray: NASA/CXC/B.Gaensler et al; ROSAT X-ray: NASA/ROSAT/Asaoka & Aschenbach;

Radio Wide: NRC/DRAO/D.Leahy; Radio Detail: NRAO/VLA; Optical: DSS

Explanation: IC 443 is typical of the aftermath of a stellar explosion, the ultimate fate of massive stars. Seen in this false-color composite image, the supernova remnant is still glowing across the spectrum, from radio (blue) to optical (red) to x-ray (green) energies -- even though light from the stellar explosion that created the expanding cosmic cloud first reached planet Earth thousands of years ago. The odd thing about IC 443 is the apparent motion of its dense neutron star, the collapsed remnant of the stellar core. The close-up inset shows the swept-back wake created as the neutron star hurtles through the hot gas, but that direction is not aligned with the direction toward the apparent center of the remnant. The misalignment suggests that the explosion site was offset from the center or that fast-moving gas in the nebula has influenced the wake. The wide view of IC 443, also known as the Jellyfish nebula, spans about 65 light-years at the supernova remnant's estimated distance of 5,000 light-years.

---------------

Very pretty

[kaknelson]

Scientific description:

The Rosette Nebula is a huge cloud of glowing gas heated by stars created only a few million years ago when a giant molecular cloud collapsed. The newborn open cluster that now stands in its center is NGC 2244. It contains many hot, bright stars that are emitting copious quantities of ultra-violet light. Such radiation strips electrons from interstellar gas atoms, turning the atoms into ions, and the gas into a glowing plasma. Ionized hydrogen emits a very intense red light and oxygen ions emit green light. Mixing the light from these two common elements gives the yellow color seen on this image. Interestingly, the abundance of gaseous oxygen revealed by images such as these, and similar studies, points out that several generations of stars must have contributed to the enrichment of the original molecular cloud over the billions of years of evolution of our galaxy. The cycle of star birth, death and rebirth will continue for billions of years to come.

Another consequence of the high energy radiation from the massive stars in NGC 2244 is the hole cleared in the center of the nebula. Within a few tens of million years, this spectacular cloud complex will have disappeared, leaving perhaps a trace of dust that might form a reflection nebula similar to that seen near Messier 35. The interstellar dust is mixed with the gas and is very efficient at scattering and absorbing starlight. Dense pockets and lanes of dust create striking silhouettes across the Rosette.

The Rosette Nebula lies in our galaxy approximately 5,000 light years away from us. This image spans about 90 light years across, more than 65,000 times the size of our solar system!

Credit: "Canada-France-Hawaii Telescope / 2003"

[frogfish]

Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2006 June 3

Gamma-Ray Earth

Credit: Dirk Petry (GLAST Science Support Center), EUD, EGRET, NASA

Explanation: The pixelated planet above is actually our own planet Earth seen in gamma rays - the most energetic form of light. In fact, the gamma rays used to construct this view pack over 35 million electron volts (MeV) compared to a mere two electron volts (eV) for a typical visible light photon. The Earth's gamma-ray glow is indeed very faint, and this image was constructed by combining data from seven years of exposure during the life of the Compton Gamma Ray Observatory, operating in Earth orbit from 1991 to 2000. Brightest near the edge and faint near the center, the picture indicates that the gamma rays are coming from high in Earth's atmosphere. The gamma rays are produced as the atmosphere interacts with high energy cosmic rays from space, blocking the harmful radiation from reaching the surface. Astronomers need to understand Earth's gamma-ray glow well as it can interfere with observations of cosmic gamma-ray sources like pulsars, supernova remnants, and distant active galaxies powered by supermassive black holes.

[kaknelson]

The center of the starburst rings in this active galaxy is what astronomers refer to as a Seyfert nucleus. That means a supermassive black hole probably is swallowing the surrounding gas and dust. The Circinus Dwarf Galaxy is 13 million lightyears away from Earth. Because the galaxy is partly hidden from view by intervening dust of our own Milky Way galaxy, it went unnoticed until 1977. Credit: NASA/AURA/STSCI

[frogfish]

Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2006 June 4

The First Rocket Launch from Cape Canaveral

Credit: GRIN, NASA

Explanation: A new chapter in space flight began on 1950 July with the launch of the first rocket from Cape Canaveral, Florida: the Bumper 2. Shown above, the Bumper 2 was an ambitious two-stage rocket program that topped a V-2 missile base with a WAC Corporal rocket. The upper stage was able to reach then-record altitudes of almost 400 kilometers, higher than even modern Space Shuttles fly today. Launched under the direction of the General Electric Company, the Bumper 2 was used primarily for testing rocket systems and for research on the upper atmosphere. Bumper 2 rockets carried small payloads that allowed them to measure attributes including air temperature and cosmic ray impacts. Seven years later, the Soviet Union launched Sputnik I and Sputnik II, the first satellites into Earth orbit. In response, in 1958, the US created NASA.

[kaknelson]

Lunation

Credit: António Cidadão

Our Moon's appearance changes nightly. This slow-loading 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 discernable 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).