The Milky Way is the galaxy that contains our Solar System. Its name “milky” is derived from its appearance as a dim glowing band arching across the night sky in which the naked eye cannot distinguish individual stars. The term “Milky Way” is a translation of the Latin via lactea, from the Greek γαλαξίας κύκλος (galaxías kýklos, “milky circle”). From Earth, the Milky Way appears as a band because its disk-shaped structure is viewed from within. Galileo Galilei first resolved the band of light into individual stars with his telescope in 1610. Up until the early 1920s, most astronomers thought that all of the stars in the universe were contained inside of the Milky Way. Following the 1920 Great Debate between the astronomers Harlow Shapley and Heber Curtis, observations by Edwin Hubble definitively showed that the Milky Way is just one of many billions of galaxies.
The Milky Way is a barred spiral galaxy some 100,000–120,000 light-years in diameter, which contains 100–400 billion stars. It may contain at least as many planets as well. The Solar System is located within the disk, about 27,000 light-years away from the Galactic Center, on the inner edge of one of the spiral-shaped concentrations of gas and dust called the Orion Arm. The stars in the inner ≈10,000 light-years form abulge and one or more bars that radiate from the bulge. The very center is marked by an intense radio source, named Sagittarius A*, which is likely to be a supermassive black hole.
Stars and gases at a wide range of distances from the Galactic Center orbit at approximately 220 kilometers per second. The constant rotation speed contradicts the laws of Keplerian dynamics and suggests that much of the mass of the Milky Way does not emit or absorb electromagnetic radiation. This mass has been given the name “dark matter”. The rotational period is about 240 million years at the position of the Sun. The Milky Way as a whole is moving at a velocity of approximately 600 km per second with respect to extragalactic frames of reference. The oldest known star in the Milky Way is at least 13.82  billion years old and thus must have formed shortly after the Big Bang.
Surrounded by several smaller satellite galaxies, the Milky Way is part of the Local Group of galaxies, which forms a subcomponent of the Virgo Supercluster, which again forms a subcomponent of the Laniakea Supercluster.
Image credit: Robert Koprowski (Two pictures from internet mixes)
This is a composite view of the Kamzang trekking camp on the night of August 18/19, 2014 at Bear Valley deep in the Zanskar Range of northwest India. The Zanskar mountains are northeast of Great Himalaya Range and in their rain shadow so visibility is excellent. The location is a rarely visited valley at 3936m that’s two days trekking from the nearest village.
The image is a composite of 47 photographs: 7 of the campsite during evening twilight, 22 of the sky, and 18 of the surrounding hoodoos, valley and mountains taken before dawn the following morning. All were captured with a Canon 6D and Sigma 35mm f/1.4. I used an AstroTrac for the sky photographs. Exposures for the camp and valley ranged between 1/30s and 30s, f/5.0 at ISO 6400 and for the sky 30s, f/1.4 at ISO 1600.
RAW files of the sky were processed using Adobe Bridge and Photoshop CS6 using settings recommended by Roger N. Clark (www.clarkvision.com) who also gave me great advice on gear. Land and sky panoramas were assembled with PTGui Pro then combined using Photoshop. The full size image is approximately 13,000 x 10,000 pixels.
Imaging telescopes or lenses: Sigma 35mm F1.4 DG HSM “Art”
Imaging cameras: Canon 6D
Mounts: AstroTrac TT320X-AG
Software: Adobe Bridge, PTGui Pro, Adobe Photoshop CS6
Dates: Aug. 18, 2014
Frames: 22×30″ ISO1600
Integration: 0.2 hours
Avg. Moon age: 22.61 days
Avg. Moon phase: 45.04%
Bortle Dark-Sky Scale: 1.00
Locations: Bear Valley Camp, Zanskar, Jammu and Kasmir, India
Author: David J Roberts
Image Credit & Copyright: Dave Lane
The Milky Way was not created by an evaporating lake. The colorful pool of water, about 10 meters across, is known as Silex Spring and is located in Yellowstone National Park in Wyoming, USA. Illuminated artificially, the colors are caused by layers of bacteria that grow in the hot spring. Steam rises off the spring, heated by a magma chamber deep underneath known as the Yellowstone hotspot. Unrelated and far in the distance, the central band of our Milky Way Galaxy arches high overhead, a band lit by billions of stars. The above picture is a 16-image panorama taken late last month. If the Yellowstone hotspot causes another supervolcanic eruption as it did 640,000 years ago, a large part of North America would be affected.
APOD NASA 27-Aug-14
Image Credit & Copyright: Petr Horálek
To some, it may look like a portal into the distant universe. To others, it may appear as the eye of a giant. Given poetic license, both are correct. Pictured above is a standard fisheye view of the sky — but with an unusual projection. The view is from a perch in New Zealand called Te Mata Peak, a name that translates from the Maori language as “Sleeping Giant”. The wondrous panorama shows the band of our Milky Way Galaxy right down the center of the sky, with the Large and Small Magellanic Clouds visible to the right. The red hue is atmospheric airglow that surprised the photographer as it was better captured by the camera than the eye. The above image was taken two weeks ago as the photographer’s sister, on the left, and an acquaintance peered into the sky portal.
APOD NASA 29-Jul-2014
Image Credit & Copyright: Yuri Beletsky (Las Campanas Observatory, Carnegie Institution)
This alluring all-skyscape was taken 5,100 meters above sea level, from the Chajnantor Plateau in the Chilean Andes. Viewed through the site’s rarefied atmosphere at about 50% sea level pressure, the gorgeous Milky Way stretches through the scene. Its cosmic rifts of dust, stars, and nebulae are joined by Venus, a brilliant morning star immersed in a strong band of predawn Zodiacal light. Still not completely dark even at this high altitude, the night sky’s greenish cast is due to airglow emission from oxygen atoms. Around the horizon the dish antenna units of the Atacama Large Millimeter/submillimeter Array, ALMA, explore the universe at wavelengths over 1,000 times longer than visible light.
APOD NASA 24-Julio-2014
Image Credit & Copyright: Rogelio Bernal Andreo (Deep Sky Colors)
To see a vista like this takes patience, hiking, and a camera. Patience was needed in searching out just the right place and waiting for just the right time. A short hike was needed to reach this rugged perchabove a secluded cove in Julia Pfeiffer Burns State Park in California, USA. And a camera was needed for the long exposure required to bring out the faint light from stars and nebulae in the background Milky Way galaxy.Moonlight illuminated the hidden beach and inlet behind nearby trees in the above composite image taken last month. Usually obscured McWay Falls is visible just below the image center, while the Pacific Ocean is in view to its right. The above image is a high-resolution sequel to a similar image that appeared last year.
APOD NASA 29-Jun-14
Image Credit & Copyright: Jason Chu (IfA Manoa)
Are lasers from giant telescopes being used to attack the Galactic center? No. Lasers shot from telescopes are now commonly used to help increase the accuracy of astronomical observations. In some sky locations, Earth atmosphere-induced fluctuations in starlight can indicate how the air mass over a telescope is changing, but many times no bright star exists in the direction where atmospheric information is needed. In these cases, astronomers create an artificial star where they need it — with a laser. Subsequent observations of the artificial laser guide star can reveal information so detailed about the blurring effects of the Earth’s atmosphere that much of this blurring can be removed by rapidly flexing the mirror. Such adaptive optic techniques allow high-resolution ground-based observations of real stars, planets, and nebulae. Pictured above, four telescopes on Mauna Kea, Hawaii, USA are being used simultaneously to study the center of our Galaxy and so all use a laser to create an artificial star nearby.
APOD NASA 23-Jun-14
Image Credit & Copyright: Luc Perrot
The central bulge of our Milky Way Galaxy rises above a sea of clouds in this ethereal scene. An echo of the Milky Way’s dark dust lanes, the volcanic peak in foreground silhouette is on France’s Réunion Island in the southern Indian Ocean. Taken in February, the photograph was voted the winner of the 2014 International Earth and Sky Photo Contest’s Beauty of the Night Sky Category. This and other winning and noteable images from the contest were selected from over a thousand entries from 55 countries around planet Earth. Also featured in the contest compilation video (vimeo), the moving images are a testament to the importance and beauty of our world at night.
NASA APOD 19-Jun-14
Image Credit & Copyright: Alessandro Merga
Bright stars of Sagittarius and the center of our Milky Way Galaxy lie just off the wing of a Boeing 747 in this astronomical travel photo. The stratospheric scene was captured earlier this month during a flight from New York to London, 11,0000 meters above the Atlantic Ocean. Of course the sky was clear and dark at that altitude, ideal conditions for astronomical imaging. But there were challenges to overcome while looking out a passenger window of the aircraft moving at nearly 1,000 kilometers per hour (600 mph). 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. In the end, one 10 second long exposure resulted in this steady and colorful example of airborne astronomy.
NASA APOD 14-Jun-14
Image Credit & Copyright: Mike Mackinven
No, radio dishes cannot broadcast galaxies. Although they can detect them, the above image features a photogenic superposition during a dark night in New Zealand about two weeks ago. As pictured above, the central part of our Milky Way Galaxy is seen rising to the east on the image left and arching high overhead. Beneath the Galactic arc and just above the horizon are the two brightest satellite galaxies of our Milky Way, with the Small Magellanic Cloud to the left and the Large Magellanic Cloud on the right. The radio dish is the Warkworth Satellite Station located just north of Auckland.
NASA APOD 11-Jun-14