Galaxies:
Galaxies are nothing but collection of interstellar matters like Stars, Planets, Comets, Asteroids, Black holes, etc. Mostly collection of Stars is the termed used to describe Galaxy. We live in a galaxy called Milky way. Our Milky galaxy is nearly 1,00000 km in diameter and consists approximately 200 to 400 billion stars in it. Our Solar system is somewhat at the near center of the Milky way and we are so tiny in it..
Take a look at our galaxy....
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Know Some thing about Meteoroid which you wouldn't have known:
A meteoroid is a small sand to boulder-sized particle of debris in the Solar system. The visible path of a meteoroid that enters Earth's (or another body's) atmosphere is a meteor, commonly called a "shooting star" or "falling star". Many meteors are part of a meteor shower. The root word meteor comes from the Greek meteoros, meaning high in the air.
Larger than a meteoroid, the object is an asteroid; smaller than that, it is interplanetary dust. The current official definition of a meteoroid from the International Astronomical Union is "A solid object moving in interplanetary space, of a size considerably smaller than an asteroid and
Larger than a meteoroid, the object is an asteroid; smaller than that, it is interplanetary dust. The current official definition of a meteoroid from the International Astronomical Union is "A solid object moving in interplanetary space, of a size considerably smaller than an asteroid and
considerably larger than an atom."
A meteor is the visible event that occurs when a meteoroid or asteroid enters Earth's atmosphere and becomes brightly visible. For bodies with a size scale larger than the atmospheric mean free path (10 cm to several metres) the visibility is due to the heat produced by the ram pressure (not friction, as is commonly assumed) of atmospheric entry. Since the majority of meteors are from small sand-grain size meteoroid bodies, most visible signatures are caused by electron relaxation following the individual collisions between vaporized meteor atoms and atmospheric constituents. The meteor is simply the visible event rather than an object itself.
A fireball is brighter than a usual meteor. The International Astronomical Union defines a fireball as "a meteor brighter than any of the planets" (magnitude -4 or greater).[3] The International Meteor Organization (an amateur organization that studies meteors) has a more rigid definition. It defines a fireball as a meteor that would have a magnitude of -3 or brighter if seen at zenith. This definition corrects for the greater distance between an observer and a meteor near the horizon. For example, a meteor of magnitude -1 at 5 degrees above the horizon would be classified as a fireball because if the observer had been directly below the meteor it would have appeared as magnitude 6.
A fireball is brighter than a usual meteor. The International Astronomical Union defines a fireball as "a meteor brighter than any of the planets" (magnitude -4 or greater).[3] The International Meteor Organization (an amateur organization that studies meteors) has a more rigid definition. It defines a fireball as a meteor that would have a magnitude of -3 or brighter if seen at zenith. This definition corrects for the greater distance between an observer and a meteor near the horizon. For example, a meteor of magnitude -1 at 5 degrees above the horizon would be classified as a fireball because if the observer had been directly below the meteor it would have appeared as magnitude 6.
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How solar system formed?
In general in the Solar System, planetary formation is thought to have occurred via a process comparable to the long-standing nebular hypothesis: a cloud of interstellar dust and gas collapsed under the influence of gravity to form a rotating disk of material that then further condensed to form the Sun and planets. During the first few million years of the Solar System's history, an accretion process of sticky collisions caused the clumping of small particles, which gradually increased in size. Once the clumps reached sufficient mass, they could draw in other bodies through gravitational attraction and become planetesimals. This gravitational accretion led to the formation of the rocky planets and the gas giants.
Comet Fact:
Comets are small Solar System bodies that orbit the Sun and, when close enough to the Sun, exhibit a visible coma (or atmosphere) and/or a tail — both primarily from the effects of solar radiation upon the comet's nucleus. Comet nuclei are themselves loose collections of ice, dust and small rocky particles, measuring a few kilometres or tens of kilometres across.
Comets have a variety of different orbital periods, ranging from a few years, to hundreds of thousands of years, while some are believed to pass through the inner Solar System only once before being thrown out into interstellar space. Short-period comets are thought to originate in the Kuiper Belt, or associated scattered disc, which lie beyond the orbit of Neptune. Long-period comets are believed to originate at a very much greater distance from the Sun, in a cloud (the Oort cloud) consisting of debris left over from the condensation of the solar nebula. Comets are thrown from these outer reaches of the Solar System inwards towards the Sun by gravitational perturbations from the outer planets (in the case of Kuiper Belt objects) or nearby stars (in the case of Oort Cloud objects), or as a result of collisions.
Comets are distinguished from asteroids by the presence of a coma and/or tail, though very old comets that have lost all their volatile materials may come to resemble asteroids. Asteroids are also believed to have a different origin from comets, having formed in the inner Solar System rather than the outer Solar System. Recent findings have, however, somewhat blurred the distinction between asteroids and comets.
Comet nuclei are in a range from 1/2 kilometer to 50 kilometers across and are composed of rock, dust, water ice, and frozen gases such as carbon monoxide, carbon dioxide, methane and ammonia. They are often popularly described as "dirty snowballs", though recent observations have revealed dry dusty or rocky surfaces, suggesting that the ices are hidden beneath the crust (see Debate over comet composition). Comets also contain a variety of organic compounds; in addition to the gases already mentioned, these may include methanol, hydrogen cyanide, formaldehyde, ethanol and ethane, and perhaps more complex molecules such as long-chain hydrocarbons and amino acids. Comet nuclei are irregularly shaped: they have insufficient mass (and hence gravity) to become spherical.
Comets have a variety of different orbital periods, ranging from a few years, to hundreds of thousands of years, while some are believed to pass through the inner Solar System only once before being thrown out into interstellar space. Short-period comets are thought to originate in the Kuiper Belt, or associated scattered disc, which lie beyond the orbit of Neptune. Long-period comets are believed to originate at a very much greater distance from the Sun, in a cloud (the Oort cloud) consisting of debris left over from the condensation of the solar nebula. Comets are thrown from these outer reaches of the Solar System inwards towards the Sun by gravitational perturbations from the outer planets (in the case of Kuiper Belt objects) or nearby stars (in the case of Oort Cloud objects), or as a result of collisions.
Comets are distinguished from asteroids by the presence of a coma and/or tail, though very old comets that have lost all their volatile materials may come to resemble asteroids. Asteroids are also believed to have a different origin from comets, having formed in the inner Solar System rather than the outer Solar System. Recent findings have, however, somewhat blurred the distinction between asteroids and comets.
Comet nuclei are in a range from 1/2 kilometer to 50 kilometers across and are composed of rock, dust, water ice, and frozen gases such as carbon monoxide, carbon dioxide, methane and ammonia. They are often popularly described as "dirty snowballs", though recent observations have revealed dry dusty or rocky surfaces, suggesting that the ices are hidden beneath the crust (see Debate over comet composition). Comets also contain a variety of organic compounds; in addition to the gases already mentioned, these may include methanol, hydrogen cyanide, formaldehyde, ethanol and ethane, and perhaps more complex molecules such as long-chain hydrocarbons and amino acids. Comet nuclei are irregularly shaped: they have insufficient mass (and hence gravity) to become spherical.
Asteroid Bel:
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 region is also termed the main belt to distinguish it from other concentrations of minor planets within the Solar System, such as the Kuiper belt and scattered disk.
During the early history of the Solar System, the asteroids melted to some degree, allowing elements within them to be partially or completely differentiated by mass. Some of the progenitor bodies may even have undergone periods of explosive volcanism and formed magma oceans. However, because of the relatively small size of the bodies, the period of melting was necessarily brief (compared to the much larger planets), and had generally ended about 4.5 billion years ago.
The current asteroid belt is believed to contain only a small fraction of the mass of the primordial belt. Computer simulations suggest that the original asteroid belt may have contained mass equivalent to the Earth. Primarily because of gravitational perturbations, most of the material was ejected from the belt within about a million years of formation, leaving behind less than 0.1% of the original mass. Since their formation, the size distribution of the asteroid belt has remained relatively stable: there has been no significant increase or decrease in the typical dimensions of the main belt asteroids.
When the main belt was first being formed, the temperatures at a distance of 2.7 AU from the Sun formed a "snow line" below the condensation point of water. Planetismals formed beyond this radius were able to accumulate ice. In 2006 it was announced that a population of comets had been discovered within the asteroid belt beyond the snow line, which may have provided a source of water for Earth's oceans. According to some models, there was insufficient outgassing of water during the Earth's formative period to form the oceans, necessitating an external source such as a cometary bombardment
During the early history of the Solar System, the asteroids melted to some degree, allowing elements within them to be partially or completely differentiated by mass. Some of the progenitor bodies may even have undergone periods of explosive volcanism and formed magma oceans. However, because of the relatively small size of the bodies, the period of melting was necessarily brief (compared to the much larger planets), and had generally ended about 4.5 billion years ago.
The current asteroid belt is believed to contain only a small fraction of the mass of the primordial belt. Computer simulations suggest that the original asteroid belt may have contained mass equivalent to the Earth. Primarily because of gravitational perturbations, most of the material was ejected from the belt within about a million years of formation, leaving behind less than 0.1% of the original mass. Since their formation, the size distribution of the asteroid belt has remained relatively stable: there has been no significant increase or decrease in the typical dimensions of the main belt asteroids.
When the main belt was first being formed, the temperatures at a distance of 2.7 AU from the Sun formed a "snow line" below the condensation point of water. Planetismals formed beyond this radius were able to accumulate ice. In 2006 it was announced that a population of comets had been discovered within the asteroid belt beyond the snow line, which may have provided a source of water for Earth's oceans. According to some models, there was insufficient outgassing of water during the Earth's formative period to form the oceans, necessitating an external source such as a cometary bombardment
Know Something about Asteroids:
Asteroids, also called minor planets or planetoids, are Solar System bodies smaller than planets but larger than meteoroids (which are commonly defined as being 10 meters across or less), and that are not comets.
The distinction between asteroids and comets is made on visual appearance when discovered: comets must show a perceptible coma (a fuzzy "atmosphere"), while asteroids do not.
Asteroids vary greatly in size, from a few hundreds of kilometres in diameter down to rocks just tens of metres across. A few of the largest are roughly spherical and are very much like miniature planets.
The vast majority, however, are much smaller and are irregularly shaped.
The physical composition of asteroids is varied and in many cases poorly understood. Some are solid rocky bodies, with a greater or lesser metallic content, while others are piles of rubble held together loosely by gravity. Only one asteroid—Vesta—is visible to the naked eye, and this only in very dark skies when it is favourably positioned.
The first named minor planet, Ceres, was discovered in 1801 by Giuseppe Piazzi, and was originally considered a new planet. This was followed by the discovery of other similar bodies, which with the equipment of the time appeared to be points of light, like stars, showing little or no planetary disc (though readily distinguishable from stars due to their apparent motions). The vast majority of known asteroids are found within the main asteroid belt, between the orbits of Mars and Jupiter, generally in relatively low-eccentricity (i.e., not very elongated) orbits. This belt is estimated to contain more than 750,000 asteroids larger than 1 kilometer across, and millions of smaller ones. It is thought that these asteroids are remnants of the protoplanetary disk, and in this region the accretion of planetesimals into planets during the formative period of the solar system was prevented by large gravitational perturbations by Jupiter. Some asteroids have moons or are found in co-orbiting pairs known as binary systems. Minor planets have more recently been found to cross the orbits of planets, from Mercury to Neptune—with hundreds of trans-Neptunian objects (TNOs) now known to exist well past Neptune's orbit. (Using indirect methods, the total number of TNOs has been estimated in the hundreds of millions or even billions.)
Asteroids are given a provisional designation by year in the order of discovery, and a designation (a sequential number) and name if their existence is well established and an orbit has been determined.
The distinction between asteroids and comets is made on visual appearance when discovered: comets must show a perceptible coma (a fuzzy "atmosphere"), while asteroids do not.
Asteroids vary greatly in size, from a few hundreds of kilometres in diameter down to rocks just tens of metres across. A few of the largest are roughly spherical and are very much like miniature planets.
The vast majority, however, are much smaller and are irregularly shaped.
The physical composition of asteroids is varied and in many cases poorly understood. Some are solid rocky bodies, with a greater or lesser metallic content, while others are piles of rubble held together loosely by gravity. Only one asteroid—Vesta—is visible to the naked eye, and this only in very dark skies when it is favourably positioned.
The first named minor planet, Ceres, was discovered in 1801 by Giuseppe Piazzi, and was originally considered a new planet. This was followed by the discovery of other similar bodies, which with the equipment of the time appeared to be points of light, like stars, showing little or no planetary disc (though readily distinguishable from stars due to their apparent motions). The vast majority of known asteroids are found within the main asteroid belt, between the orbits of Mars and Jupiter, generally in relatively low-eccentricity (i.e., not very elongated) orbits. This belt is estimated to contain more than 750,000 asteroids larger than 1 kilometer across, and millions of smaller ones. It is thought that these asteroids are remnants of the protoplanetary disk, and in this region the accretion of planetesimals into planets during the formative period of the solar system was prevented by large gravitational perturbations by Jupiter. Some asteroids have moons or are found in co-orbiting pairs known as binary systems. Minor planets have more recently been found to cross the orbits of planets, from Mercury to Neptune—with hundreds of trans-Neptunian objects (TNOs) now known to exist well past Neptune's orbit. (Using indirect methods, the total number of TNOs has been estimated in the hundreds of millions or even billions.)
Asteroids are given a provisional designation by year in the order of discovery, and a designation (a sequential number) and name if their existence is well established and an orbit has been determined.
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