background preloader


Galaxies contain varying numbers of planets, star systems, star clusters and types of interstellar clouds. In between these objects is a sparse interstellar medium of gas, dust, and cosmic rays. Supermassive black holes reside at the center of most galaxies. Galaxies have been historically categorized according to their apparent shape, usually referred to as their visual morphology. Etymology[edit] The word galaxy derives from the Greek term for our own galaxy, galaxias (γαλαξίας, "milky one"), or kyklos ("circle") galaktikos ("milky")[11] for its appearance as a lighter colored band in the sky. In the astronomical literature, the capitalized word 'Galaxy' is used to refer to our galaxy, the Milky Way, to distinguish it from the billions of other galaxies. "See yonder, lo, the Galaxyë Which men clepeth the Milky Wey, For hit is whyt." When William Herschel constructed his catalog of deep sky objects in 1786, he used the name spiral nebula for certain objects such as M31. Milky Way[edit] Related:  Extrasolar

Black hole A black hole is defined as a region of spacetime from which gravity prevents anything, including light, from escaping.[1] The theory of general relativity predicts that a sufficiently compact mass will deform spacetime to form a black hole.[2] Around a black hole, there is a mathematically defined surface called an event horizon that marks the point of no return. The hole is called "black" because it absorbs all the light that hits the horizon, reflecting nothing, just like a perfect black body in thermodynamics.[3][4] Quantum field theory in curved spacetime predicts that event horizons emit radiation like a black body with a finite temperature. This temperature is inversely proportional to the mass of the black hole, making it difficult to observe this radiation for black holes of stellar mass or greater. Objects whose gravity fields are too strong for light to escape were first considered in the 18th century by John Michell and Pierre-Simon Laplace. History General relativity

Google Androids Apps | Best Apps -The absolute 1000 best apps for iPhone, Android Oxford Dictionary of English T App for Android Review It is pretty difficult to understand English terminology for a common man, even sometimes knowledgeable persons also struggle to find out meaning for used English words and phrases. Now with the help of technology, we can now get access to Oxford dictionary online over Smartphone. Nova Launcher Prime App for Android Review Nova Launcher Prime for Android, the paid version of Nova Launcher which costs around $4, is designed to unlock extra gestures, folders in the app drawer, and other sweet features. oneSafe Password Manager App for Android Review In this day and age wherein you can do pretty much anything online, security holds the key. Ant Raid App for Android Review Fans of arcade and action will come to love this game: Ant Raid app for Android. AudioManager Pro App for Android Review Have you ever had your phone go off in office or in any other inappropriate situation? xWriter Pro 4 App for Android Review

Dark matter Dark matter is invisible. Based on the effect of gravitational lensing, a ring of dark matter has been detected in this image of a galaxy cluster (CL0024+17) and has been represented in blue.[1] Dark matter is a hypothetical kind of matter that cannot be seen with telescopes but accounts for most of the matter in the universe. The existence and properties of dark matter are inferred from its gravitational effects on visible matter, radiation, and the large-scale structure of the universe. Other than neutrinos, a form of hot dark matter, it has not been detected directly, making it one of the greatest mysteries in modern astrophysics. Astrophysicists hypothesized dark matter because of discrepancies between the mass of large astronomical objects determined from their gravitational effects and the mass calculated from the observable matter (stars, gas, and dust) that they can be seen to contain. Overview[edit] Baryonic and nonbaryonic dark matter[edit] Observational evidence[edit]

List of Messier objects The Messier objects are a set of astronomical objects catalogued by the French astronomer Charles Messier in his "Catalogue des Nébuleuses et des Amas d'Étoiles" ("Catalogue of Nebulae and Star Clusters"), originally published in 1771, with the last addition (based on Messier's observations) made in 1966.[1] Because Messier was interested in finding only comets, he created a list of non-comet objects that frustrated his hunt for them. The compilation of this list, in collaboration with his assistant Pierre Méchain, is known as the Messier catalogue. This catalogue of objects is one of the most famous lists of astronomical objects, and many Messier objects are still referenced by their Messier number.[2] The first edition included 45 objects, with Messier's final list totaling 103 objects. Messier objects[edit] Open cluster Globular cluster Nebula Planetary nebula Supernova remnant Galaxy Other Star chart of Messier objects[edit] Messier Star Chart. See also[edit] References[edit]

Spiral Galaxy An example of a spiral galaxy, the Pinwheel Galaxy (also known as Messier 101 or NGC 5457) Spiral galaxies are named for the spiral structures that extend from the center into the disk. The spiral arms are sites of ongoing star formation and are brighter than the surrounding disk because of the young, hot OB stars that inhabit them. Roughly two-thirds of all spirals are observed to have an additional component in the form of a bar-like structure,[2] extending from the central bulge, at the ends of which the spiral arms begin. The proportion of barred spirals relative to their barless cousins has changed over the history of the Universe, with only about 10% containing bars about 8 billion years ago, roughly a quarter 2.5 billion years ago, till now at over two-thirds.[3] Together with irregular galaxies, spiral galaxies make up approximately 60% of galaxies in the local Universe.[6] They are mostly found in low-density regions and are rare in the centers of galaxy clusters.[7] Other

Purchase: Two Movie Tickets - LivingSocial deal over You'd rather live in a rabbit hole or fetch your boss coffee for a month than spend another night at home alone watching old DVDs. Cue the suspense music, 'cause today's deal lets you score something far more fetching: Drop $9 and LivingSocial will give you two film tickets (a biutiful 70% discount off the maximum value of $15 per ticket). PROMOTIONAL VALUE EXPIRES ON June 6, 2011

Gravitation Gravitation, or gravity, is a natural phenomenon by which all physical bodies attract each other. It is most commonly recognized and experienced as the agent that gives weight to physical objects, and causes physical objects to fall toward the ground when dropped from a height. During the grand unification epoch, gravity separated from the electronuclear force. Gravity is the weakest of the four fundamental forces, and appears to have unlimited range (unlike the strong or weak force). The gravitational force is approximately 10-38 times the strength of the strong force (i.e., gravity is 38 orders of magnitude weaker), 10-36 times the strength of the electromagnetic force, and 10-29 times the strength of the weak force. History of gravitational theory Scientific revolution Modern work on gravitational theory began with the work of Galileo Galilei in the late 16th and early 17th centuries. Newton's theory of gravitation Equivalence principle Formulations of the equivalence principle include:

COSMOS: A Spacetime odyssey Nebula Portion of the Carina nebula A nebula (from Latin: "cloud";[1] pl. nebulae or nebulæ, with ligature, or nebulas) is an interstellar cloud of dust, hydrogen, helium and other ionized gases. Originally, nebula was a name for any diffuse astronomical object, including galaxies beyond the Milky Way. The Andromeda Galaxy, for instance, was referred to as the Andromeda Nebula (and spiral galaxies in general as "spiral nebulae") before the true nature of galaxies was confirmed in the early 20th century by Vesto Slipher, Edwin Hubble and others. Nebulae are often star-forming regions, such as in the Eagle Nebula. This nebula is depicted in one of NASA's most famous images, the "Pillars of Creation". Observational history The "Pillars of Creation" from the Eagle Nebula. On November 26, 1610, Nicolas-Claude Fabri de Peiresc discovered the Orion Nebula using a telescope. The number of nebulae was then greatly expanded by the efforts of William Herschel and his sister Caroline Herschel. Formation

Stumble Upon Stumble Upon is an application that lets you uncover websites related to your interests, as suggested by people with similar mental illnesses to yourself. It's also guaranteed to destroy any semblance of a sleeping pattern you had upon installation. So, what is it? Stumble Upon was created in 2001 by Garrett Camp, Geoff Smith, Justin LaFrance and Eric Boyd, who all agreed that they quite liked the internet and had too much free time on their hands. As of 2010, Stumble's community has reached 10 million members; which is actually bigger than the projected population of New York. In an interview with the BBC in 2007, Camp claimed that the reasoning behind Stumble was to allow its users to discover interesting information without having to trawl through search engines such as Google or Yahoo. His mother assured him that it was so he'd get nice toys for Christmas this year. What can I expect to see? Look into its eyes and tell it you hate it. Dear God, does it ever stop?!