It’s What Makes the World Go ‘Round
Planet
A planet is an astronomical body orbiting a star or stellar remnant that is massive enough to be rounded by its own gravity, is not massive enough to cause thermonuclear fusion, and has cleared its neighbouring region of planetesimals. The term planet is ancient, with ties to history, astrology, science, mythology, and religion. Five planets in the Solar System are visible to the naked eye. These were regarded by many early cultures as divine, or as emissaries of deities. As scientific knowledge advanced, human perception of the planets changed, incorporating a number of disparate objects. In 2006, the International Astronomical Union (IAU) officially adopted a resolution defining planets within the Solar System. This definition is controversial because it excludes many objects of planetary mass based on where or what they orbit. Although eight of the planetary bodies discovered before 1950 remain planets under the modern definition, some celestial bodies, such as Ceres, Pallas, Juno and Vesta (each an object in the solar asteroid belt), and Pluto (the first trans-Neptunian object discovered), that were once considered planets by the scientific community, are no longer viewed as such. The planets were thought by Ptolemy to orbit Earth in deferent and epicycle motions. Although the idea that the planets orbited the Sun had been suggested many times, it was not until the 17th century that this view was supported by evidence from the first telescopic astronomical observations, performed by Galileo Galilei. At about the same time, by careful analysis of pre-telescopic observational data collected by Tycho Brahe, Johannes Kepler found the planets orbits were elliptical rather than circular. As observational tools improved, astronomers saw that, like Earth, each of
the planets rotated around an axis tilted with respect to its orbital pole, and some shared such features as ice caps and seasons. Since the dawn of the Space Age, close observation by space probes has found that Earth and the other planets share characteristics such as volcanism, hurricanes, tectonics, and even hydrology. Planets are generally divided into two main types: large lowdensity giant planets, and smaller rocky terrestrials. There are eight planets in the Solar System. In order of increasing distance from the Sun, they are the four terrestrials, Mercury, Venus, Earth, and Mars, then the four giant planets, Jupiter, Saturn, Uranus, and Neptune. Six of the planets are orbited by one or more natural satellites. Several thousands of planets around other stars (“extrasolar planets” or “exoplanets”) have been discovered in the Milky Way. As of 1 November 2018, 3,874 known extrasolar planets in 2,892 planetary systems (including 638 multiple planetary systems), ranging in size from just above the size of the Moon to gas giants about twice as large as Jupiter have been discovered, out of which more than 100 planets are the same size as Earth, nine of which are at the same relative distance from their star as Earth from the Sun, i.e. in the circumstellar habitable zone. On December 20, 2011, the Kepler Space Telescope team reported the discovery of the first Earth-sized extrasolar planets, Kepler-20e and Kepler-20f, orbiting a Sun-like star, Kepler-20. A 2012 study, analyzing gravitational microlensing data, estimates an average of at least 1.6 bound planets for every star in the Milky Way. Around one in five Sun-like stars is thought to have an Earth-sized planet in its habitable zone.
A season is a division of the year marked by changes in weather, ecology, and amount of daylight. On Earth, seasons result from Earth’s orbit around the Sun and Earth's axial tilt relative to the ecliptic plane. In temperate and polar regions, the seasons are marked by changes in the intensity of sunlight that reaches the Earth's surface, variations of which may cause animals to undergo hibernation or to migrate, and plants to be dormant. During May, June, and July, the Northern Hemisphere is exposed to more direct sunlight because the hemisphere faces the Sun. The same is true of the Southern Hemisphere in November, December, and January. It is Earth's axial tilt that causes the Sun to be higher in the sky during the summer months, which increases the solar flux. However, due to seasonal lag, June, July, and August are the warmest months in the Northern Hemisphere while December, January, and February are the warmest months in the Southern Hemisphere.
In temperate and subpolar regions, four calendar-based seasons are generally recognized: spring, summer, autumn or fall, and winter. Ecologists often use a six-season model for temperate climate regions: prevernal, vernal, estival, serotinal, autumnal, and hibernal. Many tropical regions have two seasons: the rainy, wet, or monsoon season and the dry season. Some have a third cool, mild, or harmattan season. Seasons often held special significance for agrarian societies, whose lives revolved around planting and harvesttimes, and the change of seasons was often attended by ritual. In some parts of the world, some other “seasons” capture the timing of important ecological events such as hurricane season, tornado season, and wildfire season. The most historically important of these are the three seasons–flood, growth, and low water–which were previously defined by the former annual flooding of the Nile in Egypt.
Season
Hibernation is a state of inactivity and metabolic depression in endotherms. Hibernation refers to a season of heterothermy characterized by low body temperature, slow breathing and heart rate, and low metabolic rate. It is most commonly observed during the winter months. Although traditionally reserved for deep hibernators such as rodents, the term has been redefined to include animals such as bears and is now applied based on active metabolic suppression rather than any absolute decline in body temperature. Many experts believe that the processes of daily torpor and hibernation form a continuum and utilize similar mechanisms. The equivalent during the summer months is aestivation. Often associated with low temperatures, the function of hibernation is to conserve energy when sufficient food is unavailable. To achieve this energy saving, an endothermic animal decreases its metabolic rate and thereby its body temperature. Hibernation may last days, weeks, or months depending on the species, ambient temperature, time of year, and the individual’s body condition. Before entering hibernation, animals need to store enough energy to last through the duration of their dormant period, possibly as long as the entire winter. Larger species become hyperphagic,
eating a large amount of food and storing the energy in fat deposits. In many small species, food caching replaces eating and becoming fat. Some species of mammals hibernate while gestating young, which are born either while the mother hibernates or shortly afterwards. For example, female polar bears go into hibernation during the cold winter months in order to give birth to their offspring. The pregnant mothers significantly increase their body mass prior to hibernation, and this increase is further reflected in the weight of the offspring. The fat accumulation enables them to provide a sufficiently warm and nurturing environment for their newborns. During hibernation, they subsequently lose 15–27% of their pre-hibernation weight by using their stored fats for energy. True hibernation is restricted to endotherms; ectotherms by definition cannot hibernate because they cannot actively downregulate their body temperature or their metabolic rate. Still, many ectothermic animals undergo periods of dormancy which are sometimes confused with hibernation. Some reptile species are said to brumate, but possible similarities between brumation and hibernation are not firmly established. Many insects, such as the wasp Polistes exclamans, exhibit periods of dormancy which have often been referred to as hibernation, despite their ectothermy.
Hibernate
Rodent
Rodents (from Latin rodere, “to gnaw”) are mammals of the order Rodentia, which are characterized by a single pair of continuously growing incisors in each of the upper and lower jaws. About 40% of all mammal species are rodents; they are found in vast numbers on all continents except Antarctica. They are the most diversified mammalian order and live in a variety of terrestrial habitats, including human-made environments. Species can be arboreal, fossorial (burrowing), or semiaquatic. Well-known rodents include mice, rats, squirrels, prairie dogs, chipmunks, porcupines, beavers, guinea pigs, hamsters, gerbils and capybaras. Other animals such as rabbits, hares, and pikas, whose incisors also grow continually, were once included with them, but are now considered to be in a separate order, the Lagomorpha. Nonetheless, Rodentia and Lagomorpha are sister groups, sharing a most recent common ancestor and forming the clade of Glires. Most rodents are small animals with robust bodies, short limbs, and long tails. They use their sharp incisors to gnaw food, excavate burrows, and defend themselves. Most eat seeds or other
plant material, but some have more varied diets. They tend to be social animals and many species live in societies with complex ways of communicating with each other. Mating among rodents can vary from monogamy, to polygyny, to promiscuity. Many have litters of underdeveloped, altricial young, while others are precocial (relatively well developed) at birth. The rodent fossil record dates back to the Paleocene on the supercontinent of Laurasia. Rodents greatly diversified in the Eocene, as they spread across continents, sometimes even crossing oceans. Rodents reached both South America and Madagascar from Africa, and were the only terrestrial placental mammals to reach and colonize Australia. Rodents have been used as food, for clothing, as pets, and as laboratory animals in research. Some species, in particular, the brown rat, the black rat, and the house mouse, are serious pests, eating and spoiling food stored by humans, and spreading diseases. Accidentally introduced species of rodents are often considered to be invasive, and have caused the extinction of numerous species, such as island birds, previously isolated from land-based predators.
Dinosaurs are a diverse group of reptiles of the clade Dinosauria. carnivorous. Evidence suggests that egg-laying and nest-building They first appeared during the Triassic period, between 243 and are additional traits shared by all dinosaurs, avian and non-avian 233.23 million years ago, although the exact origin and timing of alike. the evolution of dinosaurs is the subject of active research. They While dinosaurs were ancestrally bipedal, many extinct groups became the dominant terrestrial vertebrates after the Triassic– included quadrupedal species, and some were able to shift betJurassic extinction event 201 million years ago; their dominance ween these stances. Elaborate display structures such as horns continued through the Jurassic and Cretaceous periods. Reverse or crests are common to all dinosaur groups, and some extinct genetic engineering and the fossil record both demonstrate that groups developed skeletal modifications such as bony armor birds are modern feathered dinosaurs, having evolved from earlier and spines. While the dinosaurs’ modern-day surviving avian theropods during the late Jurassic Period. As such, birds were the lineage (birds) are generally small due to the constraints of flight, only dinosaur lineage to survive the Cretaceous–Paleogene extin- many prehistoric dinosaurs (non-avian and avian) were largection event 66 million years ago. Dinosaurs can therefore be divided bodied—the largest sauropod dinosaurs are estimated to have into avian dinosaurs, or birds; and non-avian dinosaurs, which are reached lengths of 39.7 meters (130 feet) and heights of 18 meters all dinosaurs other than birds. This article deals primarily with non- (59 feet) and were the largest land animals of all time. Still, the avian dinosaurs. idea that non-avian dinosaurs were uniformly gigantic is a misconDinosaurs are a varied group of animals from taxonomic, morph- ception based in part on preservation bias, as large, sturdy bones ological and ecological standpoints. Birds, at over 10,000 living are more likely to last until they are fossilized. Many dinosaurs species, are the most diverse group of vertebrates besides perciwere quite small: Xixianykus, for example, was only about 50cm form fish. Using fossil evidence, paleontologists have identified (20in) long. over 500 distinct genera and more than 1,000 different species Since the first dinosaur fossils were recognized in the early 19th of non-avian dinosaurs. Dinosaurs are represented on every conti- century, mounted fossil dinosaur skeletons have been major attranent by both extant species (birds) and fossil remains. Through ctions at museums around the world, and dinosaurs have become the first half of the 20th century, before birds were recognized to an enduring part of world culture. The large sizes of some dinosaur be dinosaurs, most of the scientific community believed dino- groups, as well as their seemingly monstrous and fantastic nature, saurs to have been sluggish and cold-blooded. Most research have ensured dinosaurs regular appearance in best-selling books s conducted since the 1970 , however, has indicated that all dino- and films, such as Jurassic Park. Persistent public enthusiasm for saurs were active animals with elevated metabolisms and numerous the animals has resulted in significant funding for dinosaur science, adaptations for social interaction. Some were herbivorous, others and new discoveries are regularly covered by the media.
Dinosaur
Jurassic Park
rolled until May 1993, supervised by Spielberg in Poland as he filmed Schindler’s List. The dinosaurs were created with groundbreaking computergenerated imagery by Industrial Light & Magic and with life-sized animatronic dinosaurs built by Stan Winston’s team. To showcase the film’s sound design, which included a mixture of various animal noises for the dinosaur roars, Spielberg invested in the creation of DTS, a company specializing in digital surround sound formats. Following an extensive $65 million marketing campaign, which Jurassic Park is a 1993 American science fiction adventure film included licensing deals with 100 companies, Jurassic Park premdirected by Steven Spielberg and produced by Kathleen Kennedy iered on June 9, 1993 at the Uptown Theater in Washington, and Gerald R. Molen. The first installment in the Jurassic Park D.C., and was released on June 11 in the United States. It went franchise, it is based on the 1990 novel of the same name by on to gross over $914 million worldwide in its original theatrical Michael Crichton and a screenplay written by Crichton and run, becoming the highest-grossing film of 1993 and the highestDavid Koepp. The film is set on the fictional island of Isla Nublar, grossing film ever at the time, a record held until the release of located off Central America’s Pacific Coast near Costa Rica, where Titanic (1997). It was well received by critics, who praised its billionaire philanthropist John Hammond and a small team of special effects, John Williams’ musical score, and Spielberg’s genetic scientists have created a wildlife park of de-extinct dinosaurs. When industrial sabotage leads to a catastrophic shutdown direction. Following its 3D re-release in 2013 to celebrate its of the park’s power facilities and security precautions, a small group 20th anniversary, Jurassic Park became the seventeenth film in history to surpass $1 billion in ticket sales. of visitors, along with Hammond’s grandchildren, struggle to The film won more than twenty awards, including three Acadsurvive and escape the perilous island. emy Awards for its technical achievements in visual effects and Before Crichton’s novel was published, four studios put in bids for its film rights. With the backing of Universal Studios, Spiel- sound design. Jurassic Park is considered a landmark in the development of computer-generated imagery and animatronic visual berg acquired the rights for $1.5 million before its publication in effects, and was followed by four commercially successful sequels, 1990; Crichton was hired for an additional $500,000 to adapt the novel for the screen. Koepp wrote the final draft, which left out The Lost World: Jurassic Park (1997), Jurassic Park III (2001), much of the novel’s exposition and violence and made numerous Jurassic World (2015) and Jurassic World: Fallen Kingdom (2018), changes to the characters. Filming took place in California and with a fifth and final sequel, currently titled Jurassic World 3, Hawaii between August and November 1992, and post-production scheduled for a 2021 release.
Science Fiction Film
Science fiction film (or sci-fi film) is a genre that uses speculative, fictional science-based depictions of phenomena that are not fully accepted by mainstream science, such as extraterrestrial lifeforms, alien worlds, extrasensory perception and time travel, along with futuristic elements such as spacecraft, robots, cyborgs, interstellar travel or other technologies. Science fiction films have often been used to focus on political or social issues, and to explore philosophical issues like the human condition. In many cases, tropes derived from written science fiction may be used by filmmakers ignorant of or at best indifferent to the standards of scientific plausibility and plot logic to
which written science fiction is traditionally held. The genre has existed since the early years of silent cinema, when Georges Melies’ A Trip to the Moon (1902) employed trick photography effects. The next major example in the genre was the film Metropolis (1927) - being the first feature length science fiction movie. From the 1930s to the 1950s, the genre consisted mainly of low-budget B movies. After Stanley Kubrick’s landmark 2001: A Space Odyssey (1968), the science fiction film genre was taken more seriously. In the late 1970s, big-budget science fiction films filled with special effects became popular with audiences after the success of Star Wars and paved the way for the blockbuster hits of subsequent decades.
Star Wars (later retitled Star Wars: Episode IV – A New Hope) is a 1977 American epic space opera film written and directed by George Lucas. It is the first film in the original Star Wars trilogy and the beginning of the Star Wars franchise. The galaxy is in the midst of a civil war. Rebel spies have stolen plans to the Galactic Empire’s Death Star, a colossal space station capable of destroying an entire planet. Princess Leia, one of the rebellion’s leaders, has the plans, but her ship is captured by Imperial forces under the command of the ruthless Darth Vader. Before she is captured, Leia hides the plans in the memory of an astromech droid, R2-D2, along with a holographic recording. R2-D2 flees in an escape pod to the desert planet Tatooine with C-3PO, a protocol droid. The droids are captured by Jawa traders, who sell them to farmers Owen and Beru Lars and their nephew Luke Skywalker. While cleaning R2-D2, Luke accidentally triggers part of Leia’s message, in which she requests help from Obi-Wan Kenobi. The next morning, Luke finds R2-D2 missing, and meets Ben Kenobi, an old hermit who reveals himself as Obi-Wan. Obi-Wan tells Luke of his days as one of the Jedi Knights, former Galactic Republic peacekeepers with supernatural powers derived from an energy called the Force, who were all but wiped out by the Empire. Contrary to his uncle’s statements, Luke learns that his father fought alongside Obi-Wan as a Jedi Knight. Obi-Wan tells Luke that Vader who was a former pupil of his, turned to the dark side of the Force and murdered Luke’s father. Obi-Wan presents Luke with his father’s weapon: a lightsaber. Obi-Wan views Leia’s complete message, in which she begs him to take the Death Star plans to her home planet of Alderaan and give them to her father for analysis. Obi-Wan invites Luke to acco-
mpany him to Alderaan and learn the ways of the Force. Luke declines, but changes his mind after discovering that Imperial stormtroopers have destroyed the farm, killing his aunt and uncle. Obi-Wan and Luke travel to Mos Eisley, where they meet smuggler Han Solo and his Wookiee first mate Chewbacca in a cantina. After a series of brief confrontations, they agree to join forces and board Han's ship, the Millennium Falcon. The group discovers that Alderaan has been destroyed by the Death Star’s super laser on order of the commanding officer, Grand Moff Tarkin, as a show of power. The Falcon is captured by the Death Star's tractor beam. While Obi-Wan goes to disable the tractor beam, Luke discovers that Leia is imprisoned on the Death Star, and rescues her with the help of Han and Chewbacca. After several escapes, the group makes its way back to the Falcon. ObiWan sacrifices himself in a lightsaber duel with Darth Vader, and the Falcon escapes amid a fierce dogfight. The Empire has planted a tracking beacon aboard the ship, and follows the Falcon to the rebels hidden base on Yavin 4. The rebels analyze the Death Star plans and identify an exhaust port that connects to the main reactor; the Death Star can be destroyed through a chain reaction. Luke joins the Rebel fighter squadron, while Han collects his payment for the transport and intends to leave. In the ensuing battle, the rebels suffer heavy losses after several unsuccessful runs. Vader leads a squadron of TIE fighters and prepares to attack Luke's X-wing fighter, but Han returns and fires at the Imperials, sending Vader spiraling away. Guided by Obi-Wan’s spirit, Luke uses the Force to destroy the Death Star seconds before it can fire on the Rebel base. On Yavin 4, Leia awards Luke and Han with medals for their heroism.
Star Wars
Space opera is a subgenre of science fiction that emphasizes space warfare, melodramatic adventure, interplanetary battles, chivalric romance, and risk-taking. Set mainly or entirely in outer space, it usually involves conflict between opponents possessing advanced abilities, futuristic weapons, and other sophisticated technology. The term has no relation to music, but is instead a play on the terms “soap opera” and “horse opera”, the latter of which was coined during the 1930s to indicate clichéd and formulaic Western movies. Space operas emerged in the 1930s and continue to be produced in literature, film, comics, television and video games. An early film which was based on space opera comic strips was Flash Gordon (1936) created by Alex Raymond. In the late 1970s, the Star Wars franchise (1977–present) created by George Lucas brought a great deal of attention to the subgenre. After the convention-breaking “New Wave”, followed by the enormous success of the Star Wars films, space opera became once again a critically acceptable subgenre. Throughout 1982-2002, the Hugo Award for best science fiction novel was often given to a space opera nominee.
Space Opera
Space Warfare
Space warfare is combat that takes place in outer space. The scope of space warfare therefore includes ground-to-space warfare, such as attacking satellites from the Earth, as well as space-to-space warfare, such as satellites attacking satellites. In the early 1960s the U.S. military produced a film called Space and National Security which depicted space warfare. From 1985 to 2002 there was a United States Space Command, which in 2002 merged with the United States Strategic Command, leaving Air Force Space Command as the primary American military space force. The Russian Space Force, established on August 10, 1992, which became an independent section of the Russian military on June 1, 2001, was replaced by the Russian Aerospace Defence Forces starting December 1, 2011, but was reestablished as a component of the Russian Aerospace Forces on August 1, 2015. Only a few incidents of space warfare have occurred in world history, and all involved training missions, as opposed to actions against real opposing forces. In 1985 a USAF pilot in an F-15 successfully shot down the P78-1, an American research satellite, in a 345-mile (555 km) orbit. In 2007 China used a missile system to destroy one of its obsolete satellites, and in 2008 the United States similarly destroyed its malfunctioning satellite USA-193. As of 2018 there have been no human casualties resulting from conflict in space. International treaties are in place that regulate conflicts in space and limit the installation of space weapon systems, especially nuclear weapons.
Outer Space
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 back-ground radiation from the Big Bang, is 2.7 kelvins (−270.45°C; −454.81°F). 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 metreand a temperature of millions of kelvins; 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. 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. 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, an altitude of 100km (62 mi)
above sea level, 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 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.