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Post by Sayaka Maizono on Sept 4, 2018 22:41:16 GMT
gweiohgoihingioaghra[bhgoahhhhhhhao ghrh ao
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Post by Sayaka Maizono on Sept 5, 2018 5:01:26 GMT
I just want to take up space!
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Post by Sayaka Maizono on Sept 5, 2018 5:02:49 GMT
I just want to take up space!
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Post by Chihiro Fujisaki on Sept 5, 2018 5:45:26 GMT
Outer space, or just space, is the expanse that exists beyond the Earth and between celestial bodies. Outer space is not completely empty—it is a hard vacuum containing a low density of particles, predominantly a plasma of hydrogen and helium as well as electromagnetic radiation, magnetic fields, neutrinos, dust, and cosmic rays. The baseline temperature, as set by the background radiation from the Big Bang, is 2.7 kelvins (−270.45 °C; −454.81 °F).[1] The plasma between galaxies accounts for about half of the baryonic (ordinary) matter in the universe; it has a number density of less than one hydrogen atom per cubic metre and a temperature of millions of kelvins;[2] local concentrations of this plasma have condensed into stars and galaxies. Studies indicate that 90% of the mass in most galaxies is in an unknown form, called dark matter, which interacts with other matter through gravitational but not electromagnetic forces.[3][4] Observations suggest that the majority of the mass-energy in the observable universe is a poorly understood vacuum energy of space, which astronomers label dark energy.[5][6] Intergalactic space takes up most of the volume of the Universe, but even galaxies and star systems consist almost entirely of empty space.
Outer space does not begin at a definite altitude above the Earth's surface. However, the Kármán line, at an altitude of 100 km (62 mi) above sea level,[7][8] is conventionally used as the start of outer space in space treaties and for aerospace records keeping. The framework for international space law was established by the Outer Space Treaty, which entered into force on 10 October 1967. This treaty precludes any claims of national sovereignty and permits all states to freely explore outer space. Despite the drafting of UN resolutions for the peaceful uses of outer space, anti-satellite weapons have been tested in Earth orbit.
Humans began the physical exploration of space during the 20th century with the advent of high-altitude balloon flights, followed by manned rocket launches. Earth orbit was first achieved by Yuri Gagarin of the Soviet Union in 1961, and unmanned spacecraft have since reached all of the known planets in the Solar System. Due to the high cost of getting into space, manned spaceflight has been limited to low Earth orbit and the Moon.
Outer space represents a challenging environment for human exploration because of the dual hazards of vacuum and radiation. Microgravity also has a negative effect on human physiology that causes both muscle atrophy and bone loss. In addition to these health and environmental issues, the economic cost of putting objects, including humans, into space is very high.
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Post by Chihiro Fujisaki on Sept 5, 2018 5:48:25 GMT
In 350 BCE, Greek philosopher Aristotle suggested that nature abhors a vacuum, a principle that became known as the horror vacui. This concept built upon a 5th-century BCE ontological argument by the Greek philosopher Parmenides, who denied the possible existence of a void in space.[9] Based on this idea that a vacuum could not exist, in the West it was widely held for many centuries that space could not be empty.[10] As late as the 17th century, the French philosopher René Descartes argued that the entirety of space must be filled.[11]
In ancient China, the 2nd century astronomer Zhang Heng became convinced that space must be infinite, extending well beyond the mechanism that supported the Sun and the stars. The surviving books of the Hsüan Yeh school said that the heavens were boundless, "empty and void of substance". Likewise, the "sun, moon, and the company of stars float in the empty space, moving or standing still".[12]
The Italian scientist Galileo Galilei knew that air had mass and so was subject to gravity. In 1640, he demonstrated that an established force resisted the formation of a vacuum. However, it would remain for his pupil Evangelista Torricelli to create an apparatus that would produce a partial vacuum in 1643. This experiment resulted in the first mercury barometer and created a scientific sensation in Europe. The French mathematician Blaise Pascal reasoned that if the column of mercury was supported by air, then the column ought to be shorter at higher altitude where the air pressure is lower.[13] In 1648, his brother-in-law, Florin Périer, repeated the experiment on the Puy de Dôme mountain in central France and found that the column was shorter by three inches. This decrease in pressure was further demonstrated by carrying a half-full balloon up a mountain and watching it gradually expand, then contract upon descent.[14]
A glass display case holds a mechanical device with a lever arm, plus two metal hemispheres attached to draw ropes
The original Magdeburg hemispheres (lower left) used to demonstrate Otto von Guericke's vacuum pump (right)
In 1650, German scientist Otto von Guericke constructed the first vacuum pump: a device that would further refute the principle of horror vacui. He correctly noted that the atmosphere of the Earth surrounds the planet like a shell, with the density gradually declining with altitude. He concluded that there must be a vacuum between the Earth and the Moon.[15]
Back in the 15th century, German theologian Nicolaus Cusanus speculated that the Universe lacked a center and a circumference. He believed that the Universe, while not infinite, could not be held as finite as it lacked any bounds within which it could be contained.[16] These ideas led to speculations as to the infinite dimension of space by the Italian philosopher Giordano Bruno in the 16th century. He extended the Copernican heliocentric cosmology to the concept of an infinite Universe filled with a substance he called aether, which did not resist the motion of heavenly bodies.[17] English philosopher William Gilbert arrived at a similar conclusion, arguing that the stars are visible to us only because they are surrounded by a thin aether or a void.[18] This concept of an aether originated with ancient Greek philosophers, including Aristotle, who conceived of it as the medium through which the heavenly bodies move.[19]
The concept of a Universe filled with a luminiferous aether remained in vogue among some scientists until the early 20th century. This form of aether was viewed as the medium through which light could propagate.[20] In 1887, the Michelson–Morley experiment tried to detect the Earth's motion through this medium by looking for changes in the speed of light depending on the direction of the planet's motion. However, the null result indicated something was wrong with the concept. The idea of the luminiferous aether was then abandoned. It was replaced by Albert Einstein's theory of special relativity, which holds that the speed of light in a vacuum is a fixed constant, independent of the observer's motion or frame of reference.[21][22]
The first professional astronomer to support the concept of an infinite Universe was the Englishman Thomas Digges in 1576.[23] But the scale of the Universe remained unknown until the first successful measurement of the distance to a nearby star in 1838 by the German astronomer Friedrich Bessel. He showed that the star 61 Cygni had a parallax of just 0.31 arcseconds (compared to the modern value of 0.287″). This corresponds to a distance of over 10 light years.[24] In 1917, Heber Curtis noted that novae in spiral nebulae were, on average, 10 magnitudes fainter than galactic novae, suggesting that the former are 100 times further away.[25] The distance to the Andromeda Galaxy was determined in 1923 by American astronomer Edwin Hubble by measuring the brightness of cepheid variables in that galaxy, a new technique discovered by Henrietta Leavitt.[26] This established that the Andromeda galaxy, and by extension all galaxies, lay well outside the Milky Way.[27]
The earliest known estimate of the temperature of outer space was by the Swiss physicist Charles É. Guillaume in 1896. Using the estimated radiation of the background stars, he concluded that space must be heated to a temperature of 5–6 K. British physicist Arthur Eddington made a similar calculation to derive a temperature of 3.18 K in 1926. German physicist Erich Regener used the total measured energy of cosmic rays to estimate an intergalactic temperature of 2.8 K in 1933.[28]
The modern concept of outer space is based on the "Big Bang" cosmology, first proposed in 1931 by the Belgian physicist Georges Lemaître.[29] This theory holds that the universe originated from a very dense form that has since undergone continuous expansion. The background energy released during the initial expansion has steadily decreased in density, leading to a 1948 prediction by American physicists Ralph Alpher and Robert Herman of a temperature of 5 K for the temperature of space.[28]
The term outward space was used in 1842 by the English poet Lady Emmeline Stuart-Wortley in her poem "The Maiden of Moscow".[30] The expression outer space was used as an astronomical term by Alexander von Humboldt in 1845.[31] It was later popularized in the writings of H. G. Wells in 1901.[32] The shorter term space is older, first used to mean the region beyond Earth's sky in John Milton's Paradise Lost in 1667.[33]
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Post by Teruteru Hanamura on Sept 5, 2018 6:06:12 GMT
On this day in 1957, 15-year-old Elizabeth Eckford encountered an angry mob when she attempted to enter Little Rock Central High School in Little Rock, Arkansas. Eckford was one of nine teenagers, known as the Little Rock Nine, who became the first African American students to attend the previously all-white Little Rock Central High School after the U.S. Supreme Court ruled school segregation unconstitutional in its famous Brown v. Board of Education decision. While the nine students had planned to enter the school together, the meeting place was changed the night before and Eckford, whose family did not have a telephone, did not learn about the change of plans. As a result, she attempted to enter the school alone through a mob of 400 angry segregationists and a blockage by the Arkansas National Guard, which the pro-segregationist governor, Orval Faubus, had ordered to block the students in violation of the Supreme Court decision. Due to the line of soldiers blockading the school and threats from the crowd, Eckford was forced to flee to a bus stop. As she sat at the bus stop crying, New York Times reporter Benjamin Fine consoled the scared girl, telling her "don't let them see you cry." Civil rights activist Grace Lorch, who had learned that Eckford had arrived separately from the other students, then arrived to escort her home. In response to Eckford and the other students being blocked from the school, Little Rock Mayor Woodrow Wilson Mann asked President Eisenhower to send federal troops to protect the students. To enforce desegregation, Eisenhower sent the US Army's 101st Airborne Division to Little Rock and federalized the entire Arkansas National Guard to remove control from the governor. The Little Rock Nine were able to start school by the end of September. Although soldiers were deployed at the school for the entire year, many of the students experienced physical and verbal abuse, including Eckford who at one point was pushed down the stairs. The governor continued to fight integration and, the following year -- in what came to be known as the "Lost Year" -- ordered Little Rock's four high schools closed rather than allow it to continue. As a result, Eckford did not graduate from Central High but took correspondence courses to complete her degree. Eckford and the rest of the Little Rock Nine were awarded the Spingarn Medal by the NAACP and she later received a BA in history at Central State University in Wilberforce, Ohio. The famous photograph pictured here shows Elizabeth Eckford on September 4, 1957 as she walked alone through a mob to Central High. Taken by Will Counts, it was a runner-up for the Pulitzer Prize for Photography. The young woman shouting in the photo, Hazel Massery, apologized to Eckford and the two made amends at a 40th anniversary celebration of the school's integration. |
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