What is science?
Science extends and enriches our lives, expands our imagination and liberates us from the bonds of ignorance and superstition. The American Physical Society affirms the precepts of modern science that are responsible for its success.
Science is the systematic enterprise of gathering knowledge about the universe and organizing and condensing that knowledge into testable laws and theories.
What is Astronomy?
Astronomy is a scientific learning of celestial bodies like planets, comets, stars, galaxies and the like and other phenomena observed outside the atmosphere of mother Earth. It also tackles the study of celestial bodies’ evolutions, chemistry, physics, meteorology, origination and movement. Finally, it also scopes the development and the formation of various aspects of our universe.
How Science and Astronomy affects your life?
Please answer us by comment!
8/18/2553
The Sun
The Sun is the star at the center of the Solar System. It has a diameter of about 1,392,000 kilometers (865,000 mi), about 109 times that of Earth, and its mass (about 2 × 1030 kilograms, 330,000 times that of Earth) accounts for about 99.86% of the total mass of the Solar System. About three quarters of the Sun's mass consists of hydrogen, while the rest is mostly helium. Less than 2% consists of heavier elements, including oxygen, carbon, neon, iron, and others
Characteristics
The Sun is a G-type main sequence star comprising about 99.8632% of the total mass of the Solar System. It is a near-perfect sphere, with an oblateness estimated at about 9 millionths,[24] which means that its polar diameter differs from its equatorial diameter by only 10 km (6 mi). As the Sun exists in a plasmatic state and is not solid, it rotates faster at its equator than at its poles. This behavior is known as differential rotation, and is caused by convection in the Sun and the movement of mass, due to steep temperature gradients from the core outwards.
Life cycle
The Sun was formed about 4.57 billion years ago when a hydrogen molecular cloud collapsed.Solar formation is dated in two ways: the Sun's current main sequence age, determined using computer models of stellar evolution and nucleocosmochronology, is thought to be about 4.57 billion years.This is in close accord with the radiometric date of the oldest Solar System material, at 4.567 billion years ago.
Sunlight
Sunlight is Earth's primary source of energy. The solar constant is the amount of power that the Sun deposits per unit area that is directly exposed to sunlight. The solar constant is equal to approximately 1,368 W/m2 (watts per square meter) at a distance of one astronomical unit (AU) from the Sun (that is, on or near Earth). Sunlight on the surface of Earth is attenuated by the Earth's atmosphere so that less power arrives at the surface—closer to 1,000 W/m2 in clear conditions when the Sun is near the zenith.
Observation and effects
Sunlight is very bright, and looking directly at the Sun with the naked eye for brief periods can be painful, but is not particularly hazardous for normal, non-dilated eyes. Looking directly at the Sun causes phosphene visual artifacts and temporary partial blindness. It also delivers about 4 milliwatts of sunlight to the retina, slightly heating it and potentially causing damage in eyes that cannot respond properly to the brightness
Views of the Sun
Sun Prominence 
A New Look at the Sun
This image of 1,500,000°C gas in the Sun's thin, outer atmosphere (corona) was taken March 13, 1996 by the Extreme Ultraviolet Imaging Telescope onboard the Solar and Heliospheric Observatory (SOHO) spacecraft. Every feature in the image traces magnetic field structures. Because of the high quality instrument, more of the subtle and detail magnetic features can be seen than ever before. (Courtesy ESA/NASA)
X-Ray Image
This is an X-ray image of the Sun obtained on February 21, 1994. The brighter regions are sources of increased X-ray emissions. (Courtesy Calvin J. Hamilton, and Yohkoh)
1991 Solar Eclipse
This image shows the total solar eclipse of July 11, 1991 as seen from Baja California. It is a digital mosaic derived from five individual photographs, each exposed correctly for a different radius in the solar corona. (Courtesy Steve Albers, Dennis DiCicco, and Gary Emerson)
A Video : Secrets of The Sun
Credit : Solarviews , Wikipidia
Gamma Radiation
What are gamma rays?
A gamma ray is a packet of electromagnetic energy--a photon. Gamma photons are the most energetic photons in the electromagnetic spectrum. Gamma rays (gamma photons) are emitted from the nucleus of some unstable (radioactive) atoms
What are the properties of gamma radiation?
Gamma photons have no mass and no electrical charge--they are pure electromagnetic energy.
Because of their high energy, gamma photons travel at the speed of light and can cover hundreds to thousands of meters in air before spending their energy. They can pass through many kinds of materials, including human tissue. Very dense materials, such as lead, are commonly used as shielding to slow or stop gamma photons.
Their wave lengths are so short that they must be measured in nanometers, billionths of a meter. They range from 3/100ths to 3/1,000ths of a nanometer.
About Gamma Radiation
- The coulomb per kilogram (C/kg) and is the amount of radiation required to create 1 coulomb of charge of each polarity in 1 kilogram of matter.
- The Gray(Gy) which has units of (J/kg) and is the amount of radiation required to deposit 1 joule of energy in 1 kilogram of any kind of matter.
Shielding
Shielding from gamma rays requires large amounts of mass. They are better absorbed by materials with high atomic numbers and high density, although neither effect is important compared to the total mass per area in the path of the gamma ray. For this reason, a lead shield is only modestly better (20-30%) as a gamma shield than an equal mass of another shielding material such as aluminum, concrete, or soil; the lead's major advantage is in its compactness.
Matter interaction
The total absorption coefficient of lead (atomic number 82) for gamma rays, plotted versus gamma energy, and the contributions by the three effects. Here, the photoelectric effect dominates at low energy. Above 5 MeV, pair production starts to dominateWhen a gamma ray passes through matter, the probability for absorption in a thin layer is proportional to the thickness of that layer. This leads to an exponential decrease of intensity with thickness. The exponential absorption holds only for a narrow beam of gamma rays. If a wide beam of gamma rays passes through a thick slab of concrete the scattering from the sides reduces the absorption.
Here μ = nσ is the absorption coefficient, measured in cm−1, n the number of atoms per cm3 in the material, σ the absorption cross section in cm2 and d the thickness of material in cm.
Video shows Gamma Radiation
Credit : stoller-eser , wikipidia
Worm Holes
A wormhole is a pathway from one part of space and time to another more distant location. You might think of it as a shortcut through space that saves you from having to travel the normal distance between two points.
Theory
A worm hole is a mathematical solution to Einstein's relativistic equation for gravity in which two parts of space-time may be joined together. Unlike black holes, they have no singularities at least in the 'vacuum solution', but certain rotating 'Kerr-Nordstrom' black holes may serve the same worm hole-like function.
Many science fiction authors like to use them to allow spacecraft to travel quickly from place to place in our universe. But all of these ideas are based on 'pure math' descriptions of how they might work, and as you know, nature is often much messier than any idealistic, abstract rendering of it. There are no perfectly straight lines in the universe, and there are not likely to be wormholes either.
A brief history of wormholes
The theory of wormholes goes back to 1916, shortly after Einstein published his general theory, when Ludwig Flamm, an obscure Austrian physicist, looked at the simplest possible solution of Einstein's field equations, known as the Schwarzschild solution (or Schwarzschild metric). This describes the gravitational field around a spherically-symmetric non-rotating mass. If the mass is sufficiently compact, the solution describes a particular form of the phenomenon now called a black hole – the Schwarzschild black hole. Flamm realized that Einstein's equations allowed a second solution, now known as a white hole, and that the two solutions,
In 1935, Einstein and Nathan Rosen further explored, it can be appreciated with hindsight, the theory of intra- or inter-universe connections in a paper2 whose actual purpose was to try to explain fundamental particles, such as electrons, in terms of spacetime tunnels threaded by electric lines of force. Their work gave rise to the formal name Einstein-Rosen bridge for what the physicist John Wheeler would later call a "wormhole." Wheeler's 1955 paper3 discusses wormholes in terms of topological entities called geons and, incidentally, provides the first (now familiar) diagram of a wormhole as a tunnel connecting two openings in different regions of spacetime.
Credit : daviddarling
White dwarf
White dwarf and Supernova
A white dwarf is a small star composed mostly of electron-degenerate matter. They are very dense; a white dwarf's mass is comparable to that of the Sun and its volume is comparable to that of the Earth
In 1910 Henry Norris Russell, Edward Charles Pickering, and Williamina Fleming found a white dwarf because it is the unusual faintness of white dwarfs
White dwarfs are thought to represent the end point of stellar evolution for main-sequence stars with masses from about 0.07 to 10 solar masses. The composition of the white dwarf produced will differ depending on the initial mass of the star.
A white dwarf is stable once formed and will continue to cool almost indefinitely; eventually, it will become a black white dwarf, also called a black dwarf
Where do White Dwarfs Come From?
Where a star ends up at the end of its life depends on the mass it was born with. Stars that have a lot of mass may end their lives as black holes or neutron stars. A low or medium mass star (with mass less than about 8 times the mass of our Sun) will become a white dwarf. A typical white dwarf is about as massive as the Sun, yet only slightly bigger than the Earth. This makes white dwarfs one of the densest forms of matter, surpassed only by neutron stars and black holes.
Credit : Nasa
A white dwarf is a small star composed mostly of electron-degenerate matter. They are very dense; a white dwarf's mass is comparable to that of the Sun and its volume is comparable to that of the Earth
In 1910 Henry Norris Russell, Edward Charles Pickering, and Williamina Fleming found a white dwarf because it is the unusual faintness of white dwarfs
Where do White Dwarfs Come From?
Where a star ends up at the end of its life depends on the mass it was born with. Stars that have a lot of mass may end their lives as black holes or neutron stars. A low or medium mass star (with mass less than about 8 times the mass of our Sun) will become a white dwarf. A typical white dwarf is about as massive as the Sun, yet only slightly bigger than the Earth. This makes white dwarfs one of the densest forms of matter, surpassed only by neutron stars and black holes.
Credit : Nasa
8/17/2553
Venus
Venus is the second planet from the Sun, orbiting it every 224.7 Earth days. The planet is named after Venus, the Roman goddess of love and beauty. After the Moon, it is the brightest natural object in the night sky, reaching an apparent magnitude of −4.6, bright enough to cast shadows. Because Venus is an inferior planet from Earth, it never appears to venture far from the Sun: its elongation reaches a maximum of 47.8°. Venus reaches its maximum brightness shortly before sunrise or shortly after sunset, for which reason it has been known as the Morning Star or the Evening Star.
The name of Venus
Venus, the Roman Goddess of Love and Beauty, is equal to the Greek goddess Aphrodite. The meaning of Venus is "charm" in archaic Latin. Venus is also known as Venus Verticordia (Goddess of Chastity) and Venus Victrix (Goddess of Victory).
About Venus
Venus is classified as a terrestrial planet and it is sometimes called Earth's "sister planet" due to the similar size, gravity, and bulk composition. Venus is covered with an opaque layer of highly reflective clouds of sulfuric acid, preventing its surface from being seen from space in visible light. Venus has the densest atmosphere of all the terrestrial planets in our solar system, consisting mostly of carbon dioxide. Venus has no carbon cycle to lock carbon back into rocks and surface features, nor does it seem to have any organic life to absorb it in biomass. A younger Venus is believed to have possessed Earth-like oceans, but these evaporated as the temperature rose, leaving a dusty dry desertscape with many slab-like rocks.
Venus Facts
The planet is named for Venus, the Roman goddess of love.
Venus is about the same size as Earth.
Venus rotates in a retrograde (backward) direction.
At its closest, Venus is only 42 million kilometers from Earth.
Venus has a thick atmosphere of carbon dioxide. Atmospheric pressure at the surface is 90 times that of Earth.
Volcanism on Venus
Volcanic Plains
Smooth plains formed by fluid lava cover most of Venus. A dense pattern of fractures covers the plains in this image. Narrow ridges and fractures such as these form when the crust is pulled and pushed by geologic forces. Width of image area: 198 km (123 mi.)
Great Volcanoes
Volcanoes of all sizes are found on Venus, from thousands of small domes that dot the plains to large mountains. This volcano, Sapas Mons, is 4 kilometers (2.5 miles) tall and surrounded by lava flows. Two steep volcanic domes occur at the summit. Both show evidence of massive landslides along their flanks. The image color is computer generated. Width of image area: 617 km (383 mi.)
Canali
Canali are lava-carved channels similar to the sinuous rilles found on the Moon. The arrows in this image point out one such feature. Canali can extend more than 5,000 kilometers (3,000 miles), longer than on any other planet. They probably formed when very hot fluid lava erupted onto the surface. Width of image area: 158 km (98 mi.) Future Missions to Venus
Even after the highly successful Magellan mission, many questions about Venus remain unanswered.
1.How old is the surface? Has Venus undergone massive volcanic resurfacing? Is volcanic activity still underway?
2.Do different areas have different kinds of rock? How do the surface and atmosphere interact chemically? How quickly does weathering occur?
3.What is the precise chemical composition of the atmosphere? How does it vary with location and altitude? When and how did Venus's runaway greenhouse effect occur? Did Venus ever have an ocean?
Future missions may answer some of these questions. They could include long-lived landers, specialized descent probes, aerobots (controllable balloons), and long-term orbital atmospheric monitoring satellites.
Europa
Europa is the sixth moon of the planet Jupiter, and the smallest of its four Galilean satellites.
Europa was discovered in 1610 by Galileo Galilei and possibly independently by Simon Marius. The naming scheme was suggested by Simon MariusSlightly smaller than Earth's Moon, Europa is primarily made of silicate rock and probably has an iron core.
Structure
About Europa
It is believed that Europa has frozen-ice upper crust, some as liquid ocean underneath the ice. Recent magnetic field data from the Galileo orbiter showed that Europa has an induced magnetic field through interaction with Jupiter's, which suggests the presence of a subsurface conductive layer. The layer is likely a salty liquid water ocean. The crust is estimated to have undergone a shift of 80°, nearly flipping over (see true polar wander), which would be unlikely if the ice were solidly attached to the mantle. Europa probably contains a metallic iron core.
• Outer surface is all of icy with Lineae.[ Lineae is lines in English ]
• There is all of liquid ocean underneath the ice. The ocean is twice of Earth’s ocean.
• In the middle of Europa is Core, it is Metallic core.
• Europa has an induced magnetic field through interaction with Jupiter's.
Atmosphere
• first described in 1995, revealed that Europa has a tenuous atmosphere composed mostly of molecular oxygen (O2).
• The surface pressure of Europa's atmosphere is 0.1 μPa.
• In 1997, the Galileo spacecraft confirmed the presence of a tenuous ionosphere around Europa created by solar radiation and energetic particles from Jupiter's magnetosphere
Orbit and Rotation
• Europa orbits Jupiter in just over three and a half days, with an orbital radius of about 670,900 km.
• With an eccentricity of only 0.009, the orbit itself is nearly circular.
• Orbit eccentricity because of Europa has an induced magnetic field through interaction with Jupiter's and Jupiter gravity
My Video can make you interested
Credit : Nineplanet
Perseus
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The God
Origin at Argos
Perseus was the son of Zeus and Danaë, who by her very name, was the archetype of all the Danaans.She was the only child of Acrisius, King of Argos. Disappointed by his lack of luck in having a son, Acrisius consulted the oracle at Delphi, who warned him that he would one day be killed by his daughter's son. Danaë was childless and to keep her so, he imprisoned her in a bronze chamber open to the sky in the courtyard of his palace:This mytheme is also connected to Ares, Oenopion, Eurystheus, etc. Zeus came to her in the form of a shower of gold, and impregnated her.Soon after was born their child Perseus— "Perseus Eurymedon for his mother gave him this name as well" (Apollonius of Rhodes, Argonautica IV).
Notable features
1. α Per (Mirfak) : The brightest star of this constellation. Its luminosity is 5,000 times, and its diameter is 62 times that of our Sun.
2. β Per (Algol) : This may not be the brightest star of this constellation, but it definitely is its most famous star. Algol (from Arabic al-Ghul, which means The Ghoul or The Demon Star) represents the eye of the gorgon Medusa. This star is the variable stars. Its apparent brightness ranges between 2.12magnitude and 3.39magnitude with a period of merely 2.867 days.
Picture of Perseus
Perseus can cut Medusa's head and show it to warrior.
A position of star and a group of star look like perseus
Perseus and his wife,Andromeda
8/16/2553
Pluto
Poor Pluto
Pluto, formal designation 134340 Pluto, is the second-largest known dwarf planet in the Solar System (after Eris) and the tenth-largest body observed directly orbiting the Sun. Originally classified as a planet, Pluto is now considered the largest member of a distinct population known ask the Kuiper belt.
A Discover of Pluto
Discovered in 1930 Pluto was long considered our solar system's ninth planet. But after the discovery of similar intriguing worlds deeper in the distant Kuiper Belt, icy Pluto was reclassified as a dwarf planet. This new class of worlds may offer some of the best evidence about the origins our solar system..
Who described Pluto ?
Venetia BurneyBorn in 11 July 1918
Died in 30April 2009
Age 90
The name Pluto was proposed by Venetia Burney (later Venetia Phair), an eleven-year-old schoolgirl in Oxford, England. Venetia was interested in classical mythology as well as astronomy, and considered the name, that of the Roman god of the underworld,The object was officially named on March 24, 1930.Each member of the Lowell Observatory was allowed to vote on a short-list of three: Minerva, Cronus and Pluto. Pluto received every vote.The name was announced on May 1, 1930. Upon the announcement, Madan gave Venetia five pounds as a reward
Atmostsphere of Pluto
Pluto's atmosphere consists of a thin envelope of nitrogen, methane, and carbon monoxide gases, which are derived from the ices of these substances on its surface. Its surface pressure ranges from 6.5 to 24 μbar. Pluto's elongated orbit is predicted to have a major effect on its atmosphere: as Pluto moves away from the Sun, its atmosphere should gradually freeze out, and fall to the ground. When Pluto is closer to the Sun, the temperature of Pluto's solid surfaceincreases, causing the ices to sublimate into gas.
Pluto Out Off Planet !
Pluto has been voted off the island. The distant, ice-covered world is no longer a true planet, according to a new definition of the term voted on by scientists today."Whoa! Pluto's dead," said astronomer Mike Brown, of the California Institute of Technology in Pasadena, as he watched a Webcast of the vote. "There are finally, officially, eight planets in the solar system."
Credit : Wikipidia
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