Galaxies

Antennae Galaxies

Photograph courtesy NASA, ESA, and the Hubble Heritage Team (STScI/AURA)-ESA/Hubble Collaboration

A Hubble Space Telescope image shows unprecedented detail of the Antennae galaxies, an intense star-forming region created when two galaxies began to collide some 200 million to 300 million years ago. The bright, blue-white areas show newly formed stars surrounded by clouds of hydrogen, which are colored pink. A similar collision is expected between our galaxy, the Milky Way, and the nearby Andromeda galaxy in several billion years.

Andromeda Galaxy

Photograph courtesy NASA/JPL/California Institute of Technology

The Andromeda galaxy, also known as Messier 31, is the largest neighboring galaxy to the Milky Way. This photo, a mosaic of ten images captured by the Galaxy Evolution Explorer spacecraft in 2003, shows blue-white regions along the galaxy's arms where new stars are forming and a central orange-white area containing older, cooler stars.

Cartwheel Galaxy

Photograph courtesy NASA/JPL-Caltech

This false-color view of the Cartwheel galaxy was created by combining images captured by four space telescopes: Galaxy Evolution Explorer, Hubble Space Telescope, Spitzer Space Telescope, and Chandra X-ray Observatory. Astronomers think a smaller galaxy, possibly one of two galaxies seen here (bottom left), passed through the center of the Cartwheel galaxy about 100 million years ago.

Large Magellanic Cloud

Photograph courtesy NASA/JPL/Hubble Heritage Team (STScI/AURA)

Sheets of debris from an exploded star swirl in the Large Magellanic Cloud (LMC) galaxy in this Hubble Space Telescope image. At a distance of about 180,000 light years, the LMC galaxy is a relatively close neighbor of the Milky Way. It can be spotted from the Earth's Southern Hemisphere without a telescope.

Milky Way Galaxy

Illustration courtesy NASA/JPL-Caltech

This 2008 illustration shows a revised look at our galaxy, the Milky Way. Scientists studying infrared images from NASA's Spitzer Space Telescope determined our galaxy's spiral has two major and two minor arms instead of four major arms, as was previously thought. The demoted arms can be seen as faint trails between the major arms, which emanate from the ends of the orange central bar.

Black Eye Galaxy

Photograph courtesy NASA and The Hubble Heritage Team (AURA/STScI)

The Black Eye or Evil Eye galaxy gets its nicknames from the band of light-absorbing dust that appears in front of the star system's bright center in this Hubble Space Telescope image. Messier 64, as the Black Eye galaxy is more formally known, is thought to have taken on its ominous appearance after it collided with another galaxy perhaps a billion years ago.

Merging Galaxies

Photograph courtesy NASA/JPL-Caltech/STScI/Vassar

Two merging galaxies located 140 million light-years from Earth resemble a giant celestial mask in this false-color image. The ice-blue eyes are actually the galaxies' cores, and the mask is their spiral arms. The galaxies, called NGC 2207 and IC 2163, began their gravitational tango about 40 million years ago and will eventually meld into one.

Cigar Galaxy

Photograph courtesy NASA/JPL-Caltech/University of Arizona

An infrared image of the Messier 82 galaxy, nicknamed the "Cigar galaxy," shows the formation's central plane in blue and white, with a halo of smoky dust in red. This red cloud, composed of hydrocarbon dust similar to car exhaust, is being blown out into space by the galaxy's millions of young stars.

Spiral Galaxy

Photograph courtesy NASA, ESA, and the Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration

This image of the Whirlpool galaxy shows the classic features of a spiral galaxy: curving outer arms where newborn stars reside and a yellowish central core, home to older stars. A companion galaxy called NGC 5195, seen here at the tip of one of Whirlpool's arms (right), has been passing by for hundreds of millions of years and exerting gravitational forces on its larger neighbor.

Nearby Galaxy

Photograph courtesy NASA/JPL/Caltech/R. Hurt (SSC)

A color-composite image shows the NGC 300 galaxy, a spiral galaxy like the Milky Way located about seven million light-years from Earth. In this image, young, hot stars are the blue dots that comprise much of the outer arms. Older stars are in the middle and appear yellow-green.

Elliptical Galaxy

Photograph courtesy NASA, ESA, and the Hubble Heritage Team (STScI/AURA)

Billows of cosmic dust swirl amid NGC 1316, a giant elliptical galaxy formed billions of years ago when two spiral galaxies merged. Astronomers examined red star clusters within NGC 1316 to determine that the massive galaxy was indeed created by a major celestial collision.

• Messier 81 Galaxy

• Photograph courtesy NASA/JPL-Caltech/ESA/Harvard-Smithsonian CfA

  A composite image of the Messier 81 (M81) galaxy shows what astronomers call a "grand design" spiral galaxy, where each of its arms curls all the way down into its center. Located about 12 million light-years away in the Ursa Major constellation, M81 is among the brightest of the galaxies visible by telescope from Earth.

• source : http://nationalgeographic.com