milky-way-galaxy

Peering deep into the heart of the Milky Way, this image shows a region of the sky in the constellation of Sagittarius. The two knots of stars you see are the globular clusters NGC 6522 (upper right) and NGC 6528 (lower left). There are over 200,000 stars in this image alone which covers a patch of sky just two-thirds as wide as the full moon.

The vastness of the cosmos is staggering.

Photo by Adam Block/Mount Lemmon SkyCenter/University of Arizona
Info Credit: Phil Plait, Bad Astronomy

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Galactic Center of Our Milky Way

The Hubble Space Telescope, the Spitzer Space Telescope, and the Chandra X-ray Observatory – collaborated to produce an unprecedented image of the central region of our Milky Way galaxy.

Observations using infrared light and X-ray light see through the obscuring dust and reveal the intense activity near the galactic core. The center of the galaxy is located within the bright white region in the upper portion of the image. The entire image covers about one-half a degree, about the same angular width as the full moon.

Each telescope’s contribution is presented in a different color:

  • Yellow represents the near-infrared observations of Hubble. They outline the energetic regions where stars are being born as well as reveal hundreds of thousands of stars.
  • Red represents the infrared observations of Spitzer. The radiation and winds from stars create glowing dust clouds that exhibit complex structures from compact, spherical globules to long, stringy filaments.
  • Blue and violet represents the X-ray observations of Chandra. X-rays are emitted by gas heated to millions of degrees by stellar explosions and by outflows from the supermassive black hole in the galaxy’s center. The bright blue blob toward the bottom of the full field image is emission from a double star system containing either a neutron star or a black hole.
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Astronomers at the European Southern Observatory’s Paranal Observatory in Chile have released a breathtaking new photograph showing the central area of our Milky Way galaxy. The photograph shows a whopping 84 million stars in an image measuring 108500×81500, which contains nearly 9 billion pixels.

Crops of the zoomable version.

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“We inhabit a universe where atoms are made in the centers of stars; where each second a thousand suns are born; where life is sparked by sunlight and lightning in the airs and waters of youthful planets; where the raw material for biological evolution is sometimes made by the explosion of a star halfway across the Milky Way; where a thing as beautiful as a galaxy is formed a hundred billion times - a Cosmos of quasars and quarks, snowflakes and fireflies, where there may be black holes and other universe and extraterrestrial civilizations whose radio messages are at this moment reaching the Earth.”

                                                                    Carl Sagan, Cosmos

Scientists have a theory where aliens might be hiding — and how we could talk to them

At the edges of our galaxy, tens of thousands of light-years away, massive, dense clusters of stars glom together like a humongous interstellar house party. This is where, according to astrophysicists from the Harvard-Smithsonian Center for Astrophysics, we might find intelligent alien life. And in that, lies how we could communicate with them.

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“For as long as there been humans we have searched for our place in the cosmos. Where are we? Who are we? We find that we live on an insignificant planet of a hum-drum star lost in a galaxy tucked away in some forgotten corner of a universe in which there are far more galaxies than people. This perspective is a courageous continuation of our penchant for constructing and testing mental models of the skies; the Sun as a red-hot stone, the stars as a celestial flame, the Galaxy as the backbone of night.” – CARL SAGAN 

(Photography credit: Michael Goh)

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Record-Breaking Outburst from Milky Way’s Black Hole

Astronomers have detected the largest X-ray flare ever from the supermassive black hole at the center of the Milky Way, known as Sagittarius A* (Sgr A*), using NASA’s Chandra X-ray Observatory. This event was 400 times brighter than the usual X-ray output from Sgr A*. The image contains an X-ray movie of the region close to Sgr A* and shows the giant flare, along with much steadier X-ray emission from a nearby magnetar. A magnetar is a neutron star with a strong magnetic field.

Credit: NASA/CXC/Amherst College/D.Haggard et al

How did scientists determine our location within the Milky Way galaxy–in other words, how do we know that our solar system is in the arm of a spiral galaxy, far from the galaxy’s center?

There is no short answer to this question, because astronomers have followed many lines of evidence to determine the location of the solar system in the Milky Way. But some of the general techniques can be outlined briefly.

Finding one’s location in a cloud of a hundred billion stars–when one can’t travel beyond one’s own planet–is like trying to map out the shape of a forest while tied to one of the trees. One gets a rough idea of the shape of the Milky Way galaxy by just looking around–a ragged, hazy band of light circles the sky. It is about 15 degrees wide, and stars are concentrated fairly evenly along the strip. That observation indicates that our Milky Way Galaxy is a flattened disk of stars, with us located somewhere near the plane of the disk. Were it not a flattened disk, it would look different. For instance, if it were a sphere of stars, we would see its glow all over the sky, not just in a narrow band. And if we were above or below the disk plane by a substantial amount, we would not see it split the sky in half–the glow of the Milky Way would be brighter on one side of the sky than on the other.

The position of the sun in the Milky Way can be further pinned down by measuring the distance to all the stars we can see. In the late 18th century, astronomer William Herschel tried to do this, concluding that the earth was in the center of a ‘grindstone’-shaped cloud of stars. But Herschel was not aware of the presence of small particles of interstellar dust, which obscure the light from the most distant stars in the Milky Way. We appeared to be in the center of the cloud because we could see no further in all directions. To a person tied to a tree in a foggy forest, it looks like the forest stretches equally away in all directions, wherever one is.

A major breakthrough in moving the earth from the center of the galaxy to a point about 3/5 away from the edge came in the early decades of this century, when Harlow Shapley measured the distance to the large clusters of stars called globular clusters. He found they were distributed in a spherical distribution about 100,000 light-years in diameter, centered on a location in the constellation Sagittarius. Shapley concluded (and other astronomers have since verified) that the center of the distribution of globular clusters is the center of the Milky Way as well, so our galaxy looks like a flat disk of stars embedded in a spherical cloud, or 'halo,’ of globular clusters.

In the past 75 years, astronomers have refined this picture, using a variety of techniques of radio, optical, infrared and even x-ray astronomy, to fill in the details: the location of spiral arms, clouds of gas and dust, concentrations of molecules and so on. The essential modern picture is that our solar system is located on the inner edge of a spiral arm, about 25,000 light-years from the center of the galaxy, which is in the direction of the constellation of Sagittarius.

Credit: Laurence A. Marschall in the department of physics at Gettysburg College

You’re looking at The Milky Way Galaxy, As Seen From a 747

Astrophotographer Alex Merga captured the image June 7th, while aboard a red-eye flight from New York to London. The incredible shot was taken while traveling at 600 mph from around 37,000 feet above the Atlantic Ocean.

Over 90 exposures of 30 seconds or less were attempted with a fast lens and sensitive camera setting, using a small, flexible tripod and a blanket to block reflections of interior lighting.