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Transcript of science
The big bang theory is an explanation of how universe was created. The theory states our universe started with an explosion which expanded the universe. This occurrence was not a conventional explosion but rather an event filing all of space with all of the particles of the embryonic universe rushing away from each other. The big bang didn't explode like a bomb, instead lied the foundations for the universe.
The solar nebula theory, also known as the nebular hypothesis, explains the formation and evolution of our solar system. The Solar Nebular disk model (SNDM) is the most modern variant accepted. Stars form in massive, dense clouds of molecular clouds (GMC). These clouds are gravitationally unstable, and matter coalesces into smaller, denser clumps inside. These clouds collapse and form stars.
By: Emily Gramajo,
and Erica Torres
Creation of first matter:
there is very strong evidence that most of the matter in the universe is in the form of unseen or dark matter - matter that (at least so far) cannot be seen by standard methods, but whose presence can be inferred because it influences the universe gravitationally.
When a clump of interstellar gas and dust is small and dense enough, gravity plays a decisive role in turning that material into a new star.
An elliptical galaxy is a type of galaxy having and approximately ellipsoidal shape and a smooth nearly featureless brightness profile. Unlike the flt spiral galaxies with organization and structure, they are more three-dimensional, without much structure, and their stars are somewhat random orbits around the center. the stars found in a elliptical galaxy are much older then the stars in a spiral galaxy. most elliptical galaxies are composed of older, low-mas stars, with a sparse interstellar medium and minimal star formation activity, and they the virgo supercluster, and they are not the dominant type of galaxy in the universe overall.
A spiral galaxy a certain kind of galaxy originally described by Edwin Hubble in his 1936 work The Realm of the Nebulae and, as such, forms part of the Hubble sequence. Spiral galaxies consist of a flat, rotating disc containing stars, gas and dust, and a central concentration of stars known as the bulge. These are surrounded by a much fainter halo of stars, many of which reside in globular clusters. Our own Milky Way has recently (in the 1990s) been confirmed to be a barred spiral, although the bar itself is difficult to observe from our position within the galactic disk. The most convincing evidence for its existence comes from a recent survey, performed by the Spitzer Space Telescope, of stars in the galactic center.
A Galaxy that does not have a distinct regular shape, unlike a spiral or an elliptical galaxy. The shape of an irregular galaxy is uncommon – they do not fall into any of the regular classes of the Hubble sequence, and they are often chaotic in appearance, with neither a nuclear bulge nor any trace of spiral arm structure. Collectively they are thought to make up about a quarter of all galaxies. Some irregular galaxies were once spiral or elliptical galaxies but were deformed by disorders in gravitational pull. Irregular galaxies may contain abundant amounts of gas and dust. This is not necessarily true for Dwarf Irregulars.
There are three major types of irregular galaxies:
An Irr-I galaxy (Irr I) is an irregular galaxy that features some structure but not enough to place it cleanly into the Hubble sequence. Subtypes with some spiral structure are called Sm galaxies
Subtypes without spiral structure are called Im galaxies.
An Irr-II galaxy (Irr II) is an irregular galaxy that does not appear to feature any structure that can place it into the Hubble sequence.
A dI-galaxy (or dIrrs) is a dwarf irregular galaxy. This type of galaxy is now thought to be important to understand the overall evolution of galaxies, as they tend to have a low level of metallicity and relatively high levels of gas, and are thought to be similar to the earliest galaxies that populated the Universe. They may represent a local (and therefore more recent) version of the faint blue galaxies known to exist in deep field galaxy surveys.
Some of the irregular galaxies (especially of the Magellanic type) are small spiral galaxies that are being distorted by the gravity of a larger neighbor.
Our Solar System-Planetary Nebula
A planetary nebula, often abbreviated as PN or plural PNe, is a kind of emission nebula consisting of an expanding glowing shell of ionized gas ejected from old red giant stars late in their lives. The word 'nebula' is Latin for mist or cloud and the term 'planetary nebula' is a misnomer that originated in the 1780s with astronomer William Herschel because when viewed through his telescope, these objects appeared to him to resemble the rounded shapes of planets. Hershel's name for these objects was popularly adopted and has not been changed. They are a relatively short-lived phenomenon, lasting a few tens of thousands of years, compared to a typical stellar lifetime of several billion years. our solar system was formed from a planetary nebula.
The Sun is the star at the center of the Solar System. It is almost spherical and consists of hot plasma interwoven with magnetic fields. It has a diameter of about 1,392,684 km (865,374 mi), around 109 times that of Earth, and its mass (1.989×1030 kilograms, approximately 330,000 times the mass of Earth) accounts for about 99.86% of the total mass of the Solar System. Chemically, about three quarters of the Sun's mass consists of hydrogen, whereas the rest is mostly helium. The remaining 1.69% (equal to 5,600 times the mass of Earth) consists of heavier elements, including oxygen, carbon, neon and iron, among others.
The Sun produces energy by the nuclear fusion of hydrogen into helium in its core. What that means is that, since there is a huge amount of hydrogen in the core, these atoms stick together and fuse into a helium atom. This energy is then radiated out from the core and moves across the solar system
Just like practically all stars, the life cycle of the Sun starts with a large cloud of gas and dust composed mainly of hydrogen. If this large cloud of gas and dust is cool enough, it will contract due to the gravitational attraction between the particles that make up the cloud. Eventually, the continuous contraction will put a lot of pressure on the innermost region – the core. First, the electrons that were attached to the initially neutral gases would be stripped off, forcing the gas to become charged. A charged gas is called a plasma.
An The positively charged hydrogen nuclei in the core would then collide with one another with such tremendous forces that would allow them to fuse. This process, called nuclear fusion, results into the formation of helium. The energy released by nuclear fusion prevents the star from collapsing further. At this point, when nuclear fusion occurs, what was once a cloud of gas then becomes a star. In our case, the Sun.
In the entire life cycle of the Sun, it is at this point that we now exist. The Sun keeps on burning, i.e., through nuclear fusion. These nuclear reactions produce high-energy electromagnetic waves that travel for tens of thousands of years outward. Eventually, they reach the surface and are released to space in the form of lower-energy visible, ultraviolet, and infrared light.
The Terrestrial planets
An There are four terrestrial planets in our Solar System: Mercury, Venus, Earth, and Mars. The terrestrial planets in our Solar System are also known as the inner planets because these planets are the four closest to the Sun. Terrestrial planets are also called rocky planets or telluric planets. They differ from gas giants, the outer planets, in a number of ways. Terrestrial planets share a number of common features. They are all composed mostly of rock and heavy metals. These planets have a core made of heavy metals that is mostly iron; the core is surrounded by a mantle of silicate rock. Terrestrial planets are much smaller than gas giants. The terrestrial planets also have varied terrain such as volcanoes, canyons, mountains, and craters. Another common feature among the terrestrial planets is that they have few or no moons. Mercury and Venus have none while Earth has one. Mars has two small moons. Also, the terrestrial planets do not have planetary rings like the gas planets do. The atmosphere of planets can vary from Venus’ thick carbon dioxide atmosphere to almost nothing on Mercury.
The Jovian planets
An Jovian planets are also known as gas giants. There are four Jovian planets: Jupiter, Saturn, Uranus, and Neptune. These four planets also comprise the outer planets. The term Jovian came from Jupiter, describing the other gas giants in our Solar System as Jupiter-like. Despite common belief, gas giants are not composed entirely of gas. A rocky core exists somewhere within these balls of gas, but it is difficult if not impossible as of yet, to determine where this center is. Because of the intense high temperatures in the middle of these planets, the rocky core of a gas giant is actually believed to be liquid heavy compounds, such as nickel. Thus, it is sometimes misleading when astronomers refer to the rocky core of these planets. The Jovian planets are larger than the other planets of the Solar System and have dozens of moons.
The asteroid belt is the region of the Solar System located roughly between the orbits of the planets Mars and Jupiter. It is occupied by numerous irregularly shaped bodies called asteroids or minor planets. The asteroid belt is also termed the main asteroid belt or main belt to distinguish its members from other asteroids in the Solar System such as near-Earth asteroids and trojan asteroids. About half the mass of the belt is contained in the four largest asteroids, Ceres, Vesta, Pallas, and Hygiea. Vesta, Pallas, and Hygiea have mean diameters of more than 400 km, whereas Ceres, the asteroid belt's only dwarf planet, is about 950 km in diameter.
The asteroid belt formed from the primordial solar nebula as a group of planetesimals, the smaller precursors of the planets, which in turn formed protoplanets. Between Mars and Jupiter, however, gravitational perturbations from Jupiter imbued the protoplanets with too much orbital energy for them to accrete into a planet. Collisions became too violent, and instead of fusing together, the planetesimals and most of the protoplanets shattered. As a result, 99.9% of the asteroid belt's original mass was lost in the first 100 million years of the Solar System's history. Some fragments can eventually find their way into the inner Solar System, leading to meteorite impacts with the inner planets. Asteroid orbits continue to be appreciably perturbed whenever their period of revolution about the Sun forms an orbital resonance with Jupiter. At these orbital distances, a Kirkwood gap occurs as they are swept into other orbits.
Asteroids are small, airless rocky worlds revolving around the sun that are too small to be called planets. They are also known as planetoids or minor planets. In total, the mass of all the asteroids is less than that of Earth's moon. But despite their size, asteroids can be dangerous. Many have hit Earth in the past, and more will crash into our planet in the future. That's one reason scientists study asteroids and are eager to learn more about their numbers, orbits and physical characteristics.
Most asteroids lie in a vast ring between the orbits of Mars and Jupiter. This main asteroid belt holds more than 200 asteroids larger than 60 miles (100 kilometers) in diameter. Scientists estimate the asteroid belt also contains more than 750,000 asteroids larger than three-fifths of a mile (1 km) in diameter and millions of smaller ones. Not everything in the main belt is an asteroid — for instance, comets have recently been discovered there, and Ceres, once thought of only as an asteroid, is now also considered a dwarf planet.
Many asteroids lie outside the main belt. For instance, a number of asteroids called Trojans lie along Jupiter's orbital path. Three groups — Atens, Amors, and Apollos — known as near-Earth asteroids orbit in the inner solar system and sometimes cross the path
A comet is an icy body that releases gas or dust. They are often compared to dirty snowballs, though recent research has led some scientists to call them snowy dirtballs. Comets contain dust, ice, carbon dioxide, ammonia, methane and more. Astronomers think comets are leftovers from the gas, dust, ice and rocks that initially formed the solar system about 4.6 billion years ago. The solid nucleus or core of a comet consists mostly of ice and dust coated with dark organic material, according to NASA, with the ice composed mainly of frozen water but perhaps other frozen substances as well, such as ammonia, carbon dioxide, carbon monoxide and methane. The nucleus may have a small rocky core. As a comet gets closer to the sun, the ice on the surface of the nucleus begins turning into gas, forming a cloud known as the coma. Radiation from the sun pushes dust particles away from the coma, forming a dust tail, while charged particles from the sun convert some of the comet's gases into ions, forming an ion tail. Since comet tails are shaped by sunlight and the solar wind, they always point away from the sun. At first glance, comets and asteroids may appear very similar. The difference lies in the presence of the coma and tail. Sometimes, a comet may be misidentified as an asteroid before follow-up observations reveal the presence of either or both of these features.
A nebula is a cloud of gas (hydrogen) and dust in space. Nebulae are the birthplaces of stars. A star is a luminous globe of gas producing its own heat and light by nuclear reactions (nuclear fusion). They are born from nebulae and consist mostly of hydrogen and helium gas. Surface temperatures range from 2000�C to above 30,000�C, and the corresponding colours from red to blue-white. The brightest stars have masses 100 times that of the Sun and emit as much light as millions of Suns. They live for less than a million years before exploding as supernovae. The faintest stars are the red dwarfs, less than one-thousandth the brightness of the Sun. The smallest mass possible for a star is about 8% that of the Sun (80 times the mass of the planet Jupiter), otherwise nuclear reactions do not take place. A Red Giant is a large bright star with a cool surface. It is formed during the later stages of the evolution of a star like the Sun, as it runs out of hydrogen fuel at its center. Red dwarfs are very cool, faint and small stars, approximately one tenth the mass and diameter of the Sun. They burn very slowly and have estimated lifetimes of 100 billion years. White dwarfs are very small, hot star, the last stage in the life cycle of a star like the Sun. White dwarfs are the shrunken remains of normal stars, whose nuclear energy supplies have been used up.
A supernova This is the explosive death of a star, and often results in the star obtaining the brightness of 100 million suns for a short time. There are two general types of Supernova:-
Type I These occur in binary star systems in which gas from one star falls on to a white dwarf, causing it to explode.
Type II These occur in stars ten times or more as massive as the Sun, which suffer runaway internal nuclear reactions at the ends of their lives, leading to an explosion. They leave behind neutron stars and black holes. Supernovae are thought to be main source of elements heavier than hydrogen and helium.
Neutron stars stars are composed mainly of neutrons and are produced when a supernova explodes, forcing the protons and electrons to combine to produce a neutron star. Neutron stars are very dense. Typical stars having a mass of three times the Sun but a diameter of only 20 km. If its mass is any greater, its gravity will be so strong that it will shrink further to become a black hole. Pulsars are believed to be neutron stars that are spinning very rapidly.
Black holes are believed to form from massive stars at the end of their life times. The gravitational pull in a black hole is so great that nothing can escape from it, not even light. The density of matter in a black hole cannot be measured. Black holes distort the space around them, and can often suck neighboring matter into them including stars.
After the sun spun to light, the planets of the solar system began to form. But it took another hundred million years for Earth's moon to spring into existence. The early solar system was a violent place, and a number of bodies were created that never made it to full planetary status. According to the giant impact hypothesis, one of these crashed into Earth not long after the young planet was created.
Known as Theia, the Mars-size body collided with Earth, throwing vaporized chunks of the young planet's crust into space. Gravity bound the ejected particles together, creating a moon that is the largest in the solar system in relation to its host planet. This sort of formation would explain why the moon is made up predominantly of lighter elements, making it less dense than Earth — the material that formed it came from the crust, while leaving the planet's rocky core untouched. As the material drew together around what was left of Theia's core, it would have centered near Earth's ecliptic plane, the path the sun travels through the sky, which is where the moon orbits today.
Moons around other planets
Astronomers have found at least 146 moons orbiting planets in our solar system. Another 27 moons are awaiting official confirmation of their discovery. This number does not include the six moons of the dwarf planets, nor does this tally include the tiny satellites that orbit some asteroids and other celestial objects. Of the terrestrial (rocky) planets of the inner solar system, neither Mercury nor Venus have any moons at all, Earth has one and Mars has its two small moons. In the outer solar system, the gas giants Jupiter and Saturn and the ice giants Uranus and Neptune have numerous moons. As these planets grew in the early solar system, they were able to capture objects with their large gravitational fields. Usually the term moon brings to mind a spherical object, like Earth's Moon. The two moons of Mars, Phobos and Deimos, are different. While both have nearly circular orbits and travel close to the plane of the planet's equator, they are lumpy and dark. Phobos is slowly drawing closer to Mars and could crash into the planet in 40 or 50 million years. Or the planet's gravity might break Phobos apart, creating a thin ring around Mars. Jupiter has 50 known moons (plus 17 awaiting official confirmation), including the largest moon in the solar system, Ganymede. Many of Jupiter's outer moons have highly elliptical orbits and orbit backwards (opposite to the spin of the planet). Saturn, Uranus and Neptune also have some irregular moons, which orbit far from their respective planets. Saturn has 53 known moons (plus 9 awaiting official confirmation). The chunks of ice and rock in Saturn's rings (and the particles in the rings of the other outer planets) are not considered moons, yet embedded in Saturn's rings are distinct moons or moonlets. These shepherd moons help keep the rings in line. Saturn's moon Titan, the second largest in the solar system, is the only moon with a thick atmosphere. Uranus has 27 known moons. The inner moons appear to be about half water ice and half rock. Neptune has 13 known moons. And Neptune's moon Triton is as big as the dwarf planet Pluto and orbits backwards compared with Neptune's direction of rotation.
Olympus Mon/other volcanically active bodies
The largest of the volcanoes in the Tharsis Montes region, as well as all known volcanoes in the solar system, is Olympus Mons. Olympus Mons is a shield volcano 624 km (374 mi) in diameter (approximately the same size as the state of Arizona), 25 km (16 mi) high, and is rimmed by a 6 km (4 mi) high scarp. A caldera 80 km (50 mi) wide is located at the summit of Olympus Mons. To compare, the largest volcano on Earth is Mauna Loa. Mauna Loa is a shield volcano 10 km (6.3 mi) high and 120 km (75 mi) across. The volume of Olympus Mons is about 100 times larger than that of Mauna Loa. In fact, the entire chain of Hawaiian islands (from Kauai to Hawaii) would fit inside Olympus Mons! The main difference between the volcanoes on Mars and Earth is their size; volcanoes in the Tharsis region of Mars are 10 to 100 times larger than those anywhere on Earth. The lava flows on the Martian surface are observed to be much longer, probably a result of higher eruption rates and lower surface gravity.
Another reason why the volcanoes on Mars are so massive is because the crust on Mars doesn't move the way it does on Earth. On Earth, the hot spots remain stationary but crustal plates are moving above them. The Hawaiian islands result from the northwesterly movement of the Pacific plate over a stationary hotspot producing lava. As the plate moves over the hotspot, new volcanoes are formed and the existing ones become extinct. This distributes the total volume of lava among many volcanoes rather than one large volcano. On Mars, the crust remains stationary and the lava piles up in one, very large volcano.
Evidence of past volcanic activity has been found on most planets in our solar system and on many of their moons. Our own moon has vast areas covered with ancient lava flows. Mars has Olympus Mons and Tharsis Rise, the largest volcanic features in our solar system. The surface of Venus is covered with igneous rocks and hundreds of volcanic features.
A solar flare is a sudden flash of brightness observed over the Sun's surface or the solar limb, which is interpreted as a large energy release of up to 6 × 1025 joules of energy. They are often, but not always, followed by a colossal coronal mass ejection. The flare ejects clouds of electrons, ions, and atoms through the corona of the sun into space. These clouds typically reach Earth a day or two after the event. The term is also used to refer to similar phenomena in other stars, where the term stellar flare applies. Solar flares affect all layers of the solar atmosphere (photosphere, chromosphere, and corona), when the plasma medium is heated to tens of millions of kelvins the electrons, protons, and heavier ions are accelerated to near the speed of light. They produce radiation across the electromagnetic spectrum at all wavelengths, from radio waves to gamma rays, although most of the energy is spread over frequencies outside the visual range and for this reason the majority of the flares are not visible to the naked eye and must be observed with special instruments. Flares occur in active regions around sunspots, where intense magnetic fields penetrate the photosphere to link the corona to the solar interior. Flares are powered by the sudden (timescales of minutes to tens of minutes) release of magnetic energy stored in the corona. The same energy releases may produce coronal mass ejections (CME), although the relation between CMEs and flares is still not well established. X-rays and UV radiation emitted by solar flares can affect Earth's ionosphere and disrupt long-range radio communications. Direct radio emission at decimetric wavelengths may disturb the operation of radars and other devices that use those frequencies. Solar flares were first observed on the Sun by Richard Christopher Carrington and independently by Richard Hodgson in 1859 as localized visible brightenings of small areas within a sunspot group. Stellar flares can be inferred by looking at the lightcurves produced from the telescope or satellite data of variety of other stars.
Discovered in 1930, Pluto was originally classified as the ninth planet from the Sun. Its status as a major planet fell into question following further study of it and the outer Solar System over the next 75 years. Starting in 1977 with the discovery of the minor planet Chiron, numerous icy objects similar to Pluto with eccentric orbits were found. The most notable of these is the scattered disc object Eris, discovered in 2005, which is 27% more massive than Pluto. The understanding that Pluto is only one of several large icy bodies in the outer Solar System prompted the International Astronomical Union (IAU) to formally define “planet” in 2006. This definition excluded Pluto and reclassified it as a member of the new "dwarf planet" category (and specifically as a plutoid). Astronomers who oppose this decision hold that Pluto should have remained classified as a planet, and that other dwarf planets and even moons should be added to the list of planets along with Pluto. Pluto has five known moons: Charon (the largest, with a diameter just over half that of Pluto), Nix, Hydra, Kerberos, and Styx. Pluto and Charon are sometimes described as a binary system because the barycenter of their orbits does not lie within either body. The IAU has yet to formalise a definition for binary dwarf planets, and Charon is officially classified as a moon of Pluto. On July 14, 2015, the Pluto system is due to be visited by spacecraft for the first time. The New Horizons probe will perform a flyby during which it will attempt to take detailed measurements and images of Pluto and its moons. Afterwards, the probe may visit several other objects in the Kuiper belt.