User:NatureA16/1 (2007)
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January to February 2007
The featured things
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[edit] Big Bang
December 31 - January 6
In physical cosmology, the Big Bang is the scientific theory that concerns the early development and shape of the universe. The central idea is that the theory of general relativity can be combined with the observations on the largest scales of galaxies receding from each other to extrapolate the conditions of the universe back or forward in time. A natural consequence of the Big Bang is that in the past the universe had a higher temperature and a higher density. The term "Big Bang" is used both in a narrow sense to refer to a point in time when the observed expansion of the universe (Hubble's law) began, and in a more general sense to refer to the prevailing cosmological paradigm explaining the origin and evolution of the universe. The term "Big Bang" was coined in 1949 by Fred Hoyle during a BBC radio program, The Nature of Things. Hoyle did not subscribe to the theory and intended to mock the concept. In current physical models, the universe 13.7 billion years ago would have had the form of a gravitational singularity, at which all time and distance measurements become meaningless and temperatures and pressures become infinite.
Recently featured: Nature - Tyrande Whisperwind - Warcraft III
[edit] Star
January 7 - January 13
A star is a massive, compact body of plasma in outer space that is held together by its own gravity and is sufficiently massive to sustain nuclear fusion in a very dense, hot core region. This fusion of atomic nuclei generates the energy that is continuously radiated from the outer layers of the star during much of its life span. Astronomers can determine many of the properties of a star by observing its spectrum and luminosity. Individual stars differ in their total mass, chemical composition, and age. The total mass of a star is the principal determinant in its evolution and eventual fate. Other characteristics of a star that are determined by its evolutionary history include the diameter, rotation, movement and temperature. A plot of the star's temperature against luminosity, known as a Hertzsprung-Russell diagram, allows the current age and evolutionary state of the star to be determined. Binary and multi-star systems consist of two or more stars that are gravitationally bound, and generally move around each other in stable orbits. When two such stars have a relatively close orbit, their gravitational interaction can have a significant impact on their evolution.
Recently featured: Big Bang - Nature - Tyrande Whisperwind
[edit] Photon
January 14 - January 20
The photon is the elementary particle responsible for electromagnetic phenomena. It mediates electromagnetic interactions and is the fundamental constituent of all forms of electromagnetic radiation, that is, light. The photon has zero rest mass and, in empty space, travels at a constant speed c; in the presence of matter, it can be slowed or even absorbed, transferring energy and momentum proportional to its frequency. The modern concept of the photon was developed gradually by Albert Einstein to explain experimental observations that seemed anomalous by the classical wave model of light. The photon concept has led to many advances in experimental and theoretical physics, such as lasers, Bose–Einstein condensation, quantum field theory, and the probabilistic interpretation of quantum mechanics.
Recently featured: Star - Big Bang - Nature
[edit] Hydrogen
January 21 - January 27
Hydrogen is a chemical element in the periodic table that has the symbol H and atomic number 1. At standard temperature and pressure it is a colorless, odorless, nonmetallic, univalent, tasteless, highly flammable diatomic gas. With an atomic mass of 1.00794 g/mol, hydrogen is the lightest element. It is also the most abundant, constituting roughly 75% of the universe's elemental matter. Stars in their main sequence are overwhelmingly composed of hydrogen in its plasma state. Elemental hydrogen is relatively rare on Earth, and is industrially produced from hydrocarbons, after which most free hydrogen is used "captively" (meaning locally at the production site), with the largest markets about equally divided between fossil fuel upgrading (e.g. hydrocracking) and in ammonia production (mostly for the fertilizer market). The most common naturally occurring isotope of hydrogen contains one electron and an atomic nucleus of one proton. Hydrogen can form compounds with most elements and is present in water and all organic compounds. It plays a particularly important role in acid-base chemistry, in which many reactions involve the exchange of protons between soluble molecules.
Recently featured: Photon - Star - Big Bang
[edit] Planetary habitability
January 28 - February 3
Planetary habitability is the measure of an astronomical body's potential for developing and sustaining life. It may be applied both to planets and to the natural satellites of planets. The only absolute requirement for life is an energy source (usually but not necessarily solar energy), but the notion of planetary habitability implies that many other geophysical, geochemical, and astrophysical criteria must be met before an astronomical body is able to support life. The idea that planets beyond Earth might host life is an ancient one, though historically it was framed by philosophy as much as physical science. The late 20th century saw two breakthroughs in the field. To begin with, the observation and robotic exploration of other planets and moons within the solar system has provided critical information on defining habitability criteria and allowed for substantial geophysical comparisons between the Earth and other bodies. The discovery of extrasolar planets—beginning in 1995 and accelerating thereafter—was the second milestone. It confirmed that the Sun is not unique in hosting planets and expanded the habitability research horizon beyond our own solar system.
Recently featured: Hydrogen - Photon - Star
[edit] Blue Whale
February 4 - February 10
The Blue Whale is a marine mammal belonging to the suborder of baleen whales. Blue Whales are believed to be the largest animal ever to have lived, at up to 30 metres in length and 140 tonnes or more in weight. Blue Whales were abundant in most oceans around the world up until the beginning of the twentieth century. For the first 40 years of that century they were hunted by whalers almost to extinction. Hunting of the species was outlawed by the international community in 1966. The current world population is between three and four thousand individuals. These are located in four (or possibly five) groups. The largest is in the North-East Pacific. There are two groups in the North Atlantic and one in Antarctic waters. Blue Whales found in the Indian Ocean may or may not be part of the Antarctic group.
Recently featured: Planetary habitability - Hydrogen - Photon
[edit] Death acceptance
February 11 - February 17
"I do not fear death. I had been dead for billions and billions of years before I was born, and had not suffered the slightest inconvenience from it." - Neural
Recently featured: Blue Whale - Planetary habitability - Hydrogen
[edit] Mount Pinatubo
February 18 - February 25
Mount Pinatubo is an active volcano located on the island of Luzon in the Philippines, at the intersection of the borders of the provinces of Zambales, Bataan, and Pampanga. Before 1991, the mountain was inconspicuous and heavily eroded. It was covered in dense forest which supported a population of several thousand indigenous people, the Aeta, who had fled to the mountains from the lowlands when the Spanish conquered the Philippines in 1565. The volcano's most recent eruption in June 1991 came after 500 years of dormancy, and produced one of the largest and most violent eruptions of the 20th century. Successful predictions of the onset of the climactic eruption led to the evacuation of tens of thousands of people from the surrounding areas, saving many lives, but the surrounding areas were severely damaged by pyroclastic flows, ash deposits, and later, lahars caused by rainwater remobilising earlier volcanic deposits, and thousands of houses were destroyed. The effects of the eruption were felt world-wide. It injected large amounts of aerosols into the stratosphere—more than any eruption since that of Krakatoa in 1883. Global temperatures dropped by about 0.5 °C (0.9 °F), and ozone destruction increased substantially.
Recently featured: Death acceptance - Blue Whale - Planetary habitability
[edit] Albert Einstein
February 26 - March 4
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Albert Einstein was a theoretical physicist who is widely regarded as the greatest scientist of the 20th century. He proposed the theory of relativity and also made major contributions to the development of quantum mechanics, statistical mechanics, and cosmology. He was awarded the 1921 Nobel Prize for Physics for his explanation of the photoelectric effect and "for his services to Theoretical Physics." After his general theory of relativity was formulated, Einstein became world-famous, an unusual achievement for a scientist. In his later years, his fame exceeded that of any other scientist in history, and in popular culture, Einstein has become a byword for great intelligence or even genius. His is also one of the world's most recognizable faces.
Recently featured: Mount Pinatubo - Death acceptance - Blue Whale
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