Wednesday, August 3, 2022
Thursday, December 17, 2015
La Luna
La Luna es el satélite natural de el planeta Tierra y el único cuerpo astronómico que ha sido visitado por los seres humanos. En sus distantas faces, la luna refleja parte de los rayos solares y llega a ser el cuerpo celeste más brillante en el cielo oscuro cuando llega a su face de luna llena.
La Luna se encuentra a aproximadamente 384.400 km. de la tierra, tiene un diámetro de 3,476 km, y un radio 1737.4 km.Debido a que la Luna tiene menos masa que la Tierra, la fuerza gravitacional en su superficie es de 1/6 el de la tierra. Así, el peso de una persona en su superficie seria de 5/6 comparado con el de una persona en la tierra,A pesar de la fuerza de gravedad relativa de la Luna.
Esta esta lo suficientemente cerca como para producir las mareas del océano en la Tierra. No hay vida de ningún tipo sobre la Luna, al menos eso es lo que se sabe hasta ahora. El cielo en la luna esta siempre oscuro, incluso durante el día, y las estrellas son siempre visibles.Las áreas brillantes de la luna cuanod se observa con un telescopio contiene crateres y montañas. Estas formaciones han sido creadas a travez de miles de años por el impacto de meteoritos, asteroides y cometas.
Algunos cráteres en estas montañas superan los 4 km de diametro. El más grande impacto esta situado en el Polo Sur de la luna (Cuenca Aitken) y mide 2.500 kilometros de diametro y cerca de 12 km de profundidad.Las áreas oscuras en la superficie de la Luna son conocidos como mares lunares. El término se deriva de la similitud que tienen que los cuerpos de agua que existen en la tierra. Los mares lunares se distinguen por su color oscuro. Estos se crearon a lo largo de miles de años a causa de el choque de meteoritos, quienes crearon grandes cuancas de impacto; estos, posteriormente fueron inundados por magma originado del manto lunar.
Cuando la Luna está entre el Sol y la Tierra, su lado iluminado esta en oposición con la Tierra. Los astrónomos llaman a esto: "la cara oscura de la luna nueva". En la primera noche después de la luna llena, una pequeña porción de la Luna se ve iluminada a lo largo del borde oriental de la luna. Cada noche un observador en la Tierra puede ver gradualmente una porcion mas grande de la luna iluminada.
Así como el Sol, la Luna sale por el este y se mete en el oeste. Cuando la Luna alcanza su fase nueva, esta sale con el sol y viaja con el sol en el cielo. En cada día sucesivo, la Luna sale unos 50 minutos más tarde y asi en los dias sucesivos hasta completar un mes sinodico de 29.53 dias.
La Luna se encuentra a aproximadamente 384.400 km. de la tierra, tiene un diámetro de 3,476 km, y un radio 1737.4 km.Debido a que la Luna tiene menos masa que la Tierra, la fuerza gravitacional en su superficie es de 1/6 el de la tierra. Así, el peso de una persona en su superficie seria de 5/6 comparado con el de una persona en la tierra,A pesar de la fuerza de gravedad relativa de la Luna.
Esta esta lo suficientemente cerca como para producir las mareas del océano en la Tierra. No hay vida de ningún tipo sobre la Luna, al menos eso es lo que se sabe hasta ahora. El cielo en la luna esta siempre oscuro, incluso durante el día, y las estrellas son siempre visibles.Las áreas brillantes de la luna cuanod se observa con un telescopio contiene crateres y montañas. Estas formaciones han sido creadas a travez de miles de años por el impacto de meteoritos, asteroides y cometas.
Algunos cráteres en estas montañas superan los 4 km de diametro. El más grande impacto esta situado en el Polo Sur de la luna (Cuenca Aitken) y mide 2.500 kilometros de diametro y cerca de 12 km de profundidad.Las áreas oscuras en la superficie de la Luna son conocidos como mares lunares. El término se deriva de la similitud que tienen que los cuerpos de agua que existen en la tierra. Los mares lunares se distinguen por su color oscuro. Estos se crearon a lo largo de miles de años a causa de el choque de meteoritos, quienes crearon grandes cuancas de impacto; estos, posteriormente fueron inundados por magma originado del manto lunar.
Cuando la Luna está entre el Sol y la Tierra, su lado iluminado esta en oposición con la Tierra. Los astrónomos llaman a esto: "la cara oscura de la luna nueva". En la primera noche después de la luna llena, una pequeña porción de la Luna se ve iluminada a lo largo del borde oriental de la luna. Cada noche un observador en la Tierra puede ver gradualmente una porcion mas grande de la luna iluminada.
Así como el Sol, la Luna sale por el este y se mete en el oeste. Cuando la Luna alcanza su fase nueva, esta sale con el sol y viaja con el sol en el cielo. En cada día sucesivo, la Luna sale unos 50 minutos más tarde y asi en los dias sucesivos hasta completar un mes sinodico de 29.53 dias.
Sunday, November 29, 2015
The Big Dipper (How to Locate stars)
The Big Dipper is one of the brightest and most recognizable asterisms (group of stars)
in the sky. This group of seven stars is located within the constellation Ursa Major in the night sky. and can be easily obserbed throughout the year, except fall, when it
lies low on the horizon. The group of stars in the Big Dipper forms part
of the circumpolar stars, named so because they remain near Polaris throughout the
year, therefore, they´re visible most of the times. Because the Big
Dipper is easily seen in the northern sky, it has been mentioned in the
tales of ancient cultures. Explorers and travelers often use the Big
dipper as a navigation aid.
The Big Dipper was used in ancient times as a navigation aid by sailors and other travelers. It was probably due to its brightness and to the fact that it is circumpolar to Polaris, the North Star. Depending on your location, circumpolar stars might be directly overhead for those living in the northern latitudes, and will remain visible throughout the entire year. The proximity of the Big Dipper to Polaris provides a major starting point from where to locate other stars in the sky. Indeed, Polaris is one of the major points from where to start searching stars, asterisms or constellations in the sky.
The Big Dipper, which is not a constellation by itself, forms part of the constellation of Ursa Major, and is composed of seven stars, with Dubhe, Merak, Phecda and Megrez, forming the bowl, and Alioth, Mizar and Alkaid forming the handle. While five of the stars of this asterism remain fixed within its group, the two stars at both ends, Dubhe and Alkaid are moving towards each other, and in 50,000 years from now, they will constitute the bowl of the new Big Dipper, while Phecda and Merak will become the handle.
For people living in the northern hemisphere, the Big Dipper is easily recognisible if just gazing at night sky on a clear night. The seven stars on the Big Dipper can be used to guide you into finding other stars and constellations. Polaris can be found extending an imaginary line from Merak to Dubhe, then extending these two stars distance five times straght ahead.
An imaginary line from Megrez to Phecda and about eight times that distance ahead leads to Regulus in the constellation of Leo. Another line from Megrez to Dubhe and continuing approximately seven times that distance leads to Capela in Auriga. Following the curve formed by Mizar and Alkaid leads to Arcturus in Bootes and continuing a bit further, in the same curved direction, one finds Spica in Virgo. A diagonal line from Phecda to Dubhe and stretching it to about 8 times its distance leads to Cassiopeia, easily recognisible for its five stars, forming the letter w.
Using this technique of drawing imaginary lines from star to star, it´s easy to navigate around the night sky. You may also use other asterisms or single stars to locate objects in the sky; for example, using Orion, one can locate Taurus, The Pleiades, Canis Minor, Sirius; gemini and other stars.
The Big Dipper has been known since ancient times. In the Bible, the Big Dipper is mentioned as the seven stars in Amos 5:8. In Hindu astronomy, it was known as Sapta Rishi, which means the seven great sages. In Mongolia it is known as the seven gods. In the British Isles, it is known as the Plough, although in Ireland, it is most referred as the Starry Plough. In Native American mythology, the bowl was considered as a giant bear, and the handle was a group of warriors chasing the bear.
The Big dipper never disappears from sight at latitudes of 40 degrees or more in the northern skies, and this asterism is portrayed on the Alaskan state flag, as well.
The Big Dipper was used in ancient times as a navigation aid by sailors and other travelers. It was probably due to its brightness and to the fact that it is circumpolar to Polaris, the North Star. Depending on your location, circumpolar stars might be directly overhead for those living in the northern latitudes, and will remain visible throughout the entire year. The proximity of the Big Dipper to Polaris provides a major starting point from where to locate other stars in the sky. Indeed, Polaris is one of the major points from where to start searching stars, asterisms or constellations in the sky.
The Big Dipper, which is not a constellation by itself, forms part of the constellation of Ursa Major, and is composed of seven stars, with Dubhe, Merak, Phecda and Megrez, forming the bowl, and Alioth, Mizar and Alkaid forming the handle. While five of the stars of this asterism remain fixed within its group, the two stars at both ends, Dubhe and Alkaid are moving towards each other, and in 50,000 years from now, they will constitute the bowl of the new Big Dipper, while Phecda and Merak will become the handle.
For people living in the northern hemisphere, the Big Dipper is easily recognisible if just gazing at night sky on a clear night. The seven stars on the Big Dipper can be used to guide you into finding other stars and constellations. Polaris can be found extending an imaginary line from Merak to Dubhe, then extending these two stars distance five times straght ahead.
An imaginary line from Megrez to Phecda and about eight times that distance ahead leads to Regulus in the constellation of Leo. Another line from Megrez to Dubhe and continuing approximately seven times that distance leads to Capela in Auriga. Following the curve formed by Mizar and Alkaid leads to Arcturus in Bootes and continuing a bit further, in the same curved direction, one finds Spica in Virgo. A diagonal line from Phecda to Dubhe and stretching it to about 8 times its distance leads to Cassiopeia, easily recognisible for its five stars, forming the letter w.
Using this technique of drawing imaginary lines from star to star, it´s easy to navigate around the night sky. You may also use other asterisms or single stars to locate objects in the sky; for example, using Orion, one can locate Taurus, The Pleiades, Canis Minor, Sirius; gemini and other stars.
The Big Dipper has been known since ancient times. In the Bible, the Big Dipper is mentioned as the seven stars in Amos 5:8. In Hindu astronomy, it was known as Sapta Rishi, which means the seven great sages. In Mongolia it is known as the seven gods. In the British Isles, it is known as the Plough, although in Ireland, it is most referred as the Starry Plough. In Native American mythology, the bowl was considered as a giant bear, and the handle was a group of warriors chasing the bear.
The Big dipper never disappears from sight at latitudes of 40 degrees or more in the northern skies, and this asterism is portrayed on the Alaskan state flag, as well.
Saturday, November 28, 2015
The Solar Cycle
The Sun is a big ball of fire that has a magnetic field, like oither astronomical objects in the solar system. The Sun´s magnetic field causes tremendous solar activity,
including solar flares, sunspots and solar wind reaching the entire
solar system. Every 11 years the Sun´s magnetic poles flip over,
producing periods of great solar activity (solar maximum) followed by
periods of least solar activity (solar minimum). During a solar maximum, the Sun´s activity
increases with a quantitative number of sunspots on its surface,
including solar flares blowing out into space and billions of tons of
electrified gases blasted into space, as well.
The solar cycle has been observed since the invention of the telescope, and it has been continuously observed by astronomers, to date. Astronomers have been able to discover the sun´s cycle by counting the number of sun spots appearing on the sun on a given monthly period and this indicates that the sun goes from periods of inactivity and activity during an 11-year cycle. The time period from 1645-1766 was a time during which very few sunspots were observed. This period is known as the Maunder minimum.
Sunspots may remain visible anywhere from a few days to a couple of months; however, they eventually fade away, releasing strong magnetic flux in the solar photosphere, generating the Sun´s magnetic field. The polarity of sunspots in one hemisphere is opposite to that of the sunspots of the other hemisphere, and the polarities interchange from one cycle to the next. The dipolar component of the Sun´s magnetic field reverses the polarity just about the time of the solar maximum.
Magnetic fields are stretched out and wrap around the Sun by the change in rotation rate (differential rotation). The Sun´s differential rotation can make a north-south oriented magnetic field wrap around the Sun in approximately 8 months. This twisting of the magnetic field lines is produced by the Sun´s rotation. The Sun rotates every 24 hours at the equator, and takes 35 days to rotate at the poles. The twist makes the magnetic field reverse from one sunspot cycle to the next.
The flow of material along meridian lines from the equator to the both sides of the poles through the surface and from both poles to the equator below the surface are thought to play an important role in the Sun´s magnetic dynamo. At the surface the flow is slow; however, below the surface, the flow is slower due to a higher density. This slow flow would transport material from the mid-latitudes to the poles in approximately 11 years, suggesting that the variations observed in the meridional circulation are the cause of variations in sunspot cycle.
The latest prediction for the Sun´s 11 year cycle 24 was a solar maximum in 2013; however, solar cycles are not regular and sometimes may take from 9 to 14 years to complete.Solar storms due to soalr activity can damage satellites and other space craft on the outer space eand within the earth´s atmosphere.
The solar cycle has been observed since the invention of the telescope, and it has been continuously observed by astronomers, to date. Astronomers have been able to discover the sun´s cycle by counting the number of sun spots appearing on the sun on a given monthly period and this indicates that the sun goes from periods of inactivity and activity during an 11-year cycle. The time period from 1645-1766 was a time during which very few sunspots were observed. This period is known as the Maunder minimum.
Sunspots may remain visible anywhere from a few days to a couple of months; however, they eventually fade away, releasing strong magnetic flux in the solar photosphere, generating the Sun´s magnetic field. The polarity of sunspots in one hemisphere is opposite to that of the sunspots of the other hemisphere, and the polarities interchange from one cycle to the next. The dipolar component of the Sun´s magnetic field reverses the polarity just about the time of the solar maximum.
Magnetic fields are stretched out and wrap around the Sun by the change in rotation rate (differential rotation). The Sun´s differential rotation can make a north-south oriented magnetic field wrap around the Sun in approximately 8 months. This twisting of the magnetic field lines is produced by the Sun´s rotation. The Sun rotates every 24 hours at the equator, and takes 35 days to rotate at the poles. The twist makes the magnetic field reverse from one sunspot cycle to the next.
The flow of material along meridian lines from the equator to the both sides of the poles through the surface and from both poles to the equator below the surface are thought to play an important role in the Sun´s magnetic dynamo. At the surface the flow is slow; however, below the surface, the flow is slower due to a higher density. This slow flow would transport material from the mid-latitudes to the poles in approximately 11 years, suggesting that the variations observed in the meridional circulation are the cause of variations in sunspot cycle.
The latest prediction for the Sun´s 11 year cycle 24 was a solar maximum in 2013; however, solar cycles are not regular and sometimes may take from 9 to 14 years to complete.Solar storms due to soalr activity can damage satellites and other space craft on the outer space eand within the earth´s atmosphere.
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| Public Domain via Wikimedia Commons |
Geminid Meteor Shower
Meteor showers are caused by small fragments of cosmic fragments left out by the orbits of comets. These small fragments are encountered when the Earth´s orbit passes through that orbit, producing intense streams of light which very quickly disintegrate when they enter the Earth´s atmosphere. Intense meteor showers are commonly known as, meteor outbursts or meteor storms. Meteor showers are usually named after the constellations from which they appear to radiate; for example, the Geminid Meteor Shower, which seems to radiate froom the constellation of Gemini.
The brightest meteors can be observed even from light polluted cities, at night; however, it is preferable to find a place that is as far away from city lights, especially those dark places where you can stare better the night sky without being interrupted by the glow of any light.
An observing spot, behind a building or mountain can block any glow and allow you to observe the meteors better. If observing from your house, it is recomendable to turn off any lights and also to close curtains and use blankets to prevent any infiltration of light.
Observing from outside the house, such as in a city park can be a great idea, only you must try to find a spot that has many trees and place your sky viewing devices in between them. Once you´ve found the right spot to oberve a meteor shower, you may sit comfortable with your gaze straight to where the point of radiation is. If the sky is clear and nothing perturbes the observation, you might be able to observe many meteors.
The Geminid meteor shower occurs in the month of December on the 13-15. The meteors radiate from the constellation of Gemini near Castor and Pollux. On this days, the waxing crescent moon will be setting just after sunset, and the sky usually remains clear, so you might be able to observe from 50-100 meteors per hour.
The brightest meteors can be observed even from light polluted cities, at night; however, it is preferable to find a place that is as far away from city lights, especially those dark places where you can stare better the night sky without being interrupted by the glow of any light.
An observing spot, behind a building or mountain can block any glow and allow you to observe the meteors better. If observing from your house, it is recomendable to turn off any lights and also to close curtains and use blankets to prevent any infiltration of light.
Observing from outside the house, such as in a city park can be a great idea, only you must try to find a spot that has many trees and place your sky viewing devices in between them. Once you´ve found the right spot to oberve a meteor shower, you may sit comfortable with your gaze straight to where the point of radiation is. If the sky is clear and nothing perturbes the observation, you might be able to observe many meteors.
The Geminid meteor shower occurs in the month of December on the 13-15. The meteors radiate from the constellation of Gemini near Castor and Pollux. On this days, the waxing crescent moon will be setting just after sunset, and the sky usually remains clear, so you might be able to observe from 50-100 meteors per hour.
The Gas Giant Planets (The Govian Planets)
The gas giant planets, also known as the Jovian Planets, includes the four outer planets in the solar system: Jupiter, Saturn, Uranus and Neptune.
These planets are composed of gas; however, only Jupiter and Saturn are composed mostly of hydrogen and
helium, while Uranus and Neptune, which are composed mostly of methane,
ammonia and water, are known as ice giants; However, they also contain hydrogen and helium. The gas giants do not have a solid surface, but the
gases comprising these planets become thinner with increased distance
from their solid rocky cores. Even though the giant planets are larger
and more massive than the Earth they´re less dense.
Gas giant planets lack a solid surface; however, they´re thought to have a solid metallic or rocky core due to the high pressures and temperatures in their cores. Their density increases with increasing depth to their interior. Hydrogen and helium constitute most of the atmospheres of Jupiter and Saturn, while Uranus and Neptune are composed primarily of methane, ammonia and water, with an outer envelope of hydrogen and helium. All the gas giant planets share a characteristic that differentiates them from the inner rocky planets. They all have rings and numerous moons orbiting them.
Jupiter- the largest planet in the solar system- is around 300 times more massive than the Earth. It´s composed of approximately 90 percent hydrogen (H), 9 percent helium (He) and 1 percent traces of other elements. These gases become liquid with increasing pressure and temperature. Liquid hydrogen at its core behaves like a molten metal with free electrons conducting electricity, creating Jupiter´s magnetosphere. Its rocky core is believed to be of a diameter the size of the Earth. More than 60 moons orbit Jupiter, including the Galilean moons: Ganymede, Calisto, Io and Europa.
Jupiter can be easily observed during a cloudless, moonless night with a small telescope, including the bands across its atmosphere and the Great Red Spot, which is a swirling hurricane of about twice the size of the Earth.
Saturn is the second largest planet in the solar system and the sixth planet from the Sun. The atmosphere of Saturn is similar to the one on Jupiter with about 92.4 percent hydrogen and 7.4 percent helium, with traces of ammonia and methane. Its internal, metallic hydrogen layer is thinner than Jupiter´s, while its core might be larger. Saturn´s internal pressure and temperature are less extreme than in Jupiter. The rapid rate of rotation and the conductive metallic hydrogen in Saturn´s core are thought to generate its magnetic field. Saturn´s ring system consists of nine rings composed mainly of ice, dust and rocks. 62 known moons orbit the planet. Saturn can be easily observed with the naked eye during moonless, clear nights, but a four-inch aperture telescope will enable you to observe Saturn´s rings and moons.
Uranus is believed to have a rocky core similar in size to Jupiter´s, surrounded by a layer of water clouds and ammonia. Spectroscopic studies have revealed that Uranus contains about 82 percent hydrogen and 14 percent helium in its atmosphere, with about 2 percent methane and 1 percent ammonia, along with traces of hydrocarbons. Methane absorbs red light and reflects blue, which is what gives Uranus a blue-green color. Uranus has a ring system, a magnetosphere and various moons, like the other gas giants. Its axis of rotation is tilted 98º sideways, resulting in extreme seasonal conditions at the poles, with 42 years of continuous sunlight, followed by another 42 years of continuous darkness at the other pole.
Neptune is the eighth farthest planet from the Sun. Neptune is the most dense gas giant, with about 17 times the mass of the Earth. Neptune was discovered on September 23, 1846, due to variations in the orbit of Uranus, which led astronomers to the prediction of another planet in its vicinity. Neptune´s outer envelope is composed primarily of hydrogen and helium, while methane and ammonia constitute most of its interior. There are traces of hydrocarbons, as well. Neptune´s core is composed principally of ices and rock. The small quantities of methane give Neptune its bluish appearance. Neptune has one of the coldest temperatures, -218 ºC (55 K), in the solar system.
Among the gas giant, Jupiter is the planet that astronomers refer to as a model to the rest of the Jovian planets.
Gas giant planets lack a solid surface; however, they´re thought to have a solid metallic or rocky core due to the high pressures and temperatures in their cores. Their density increases with increasing depth to their interior. Hydrogen and helium constitute most of the atmospheres of Jupiter and Saturn, while Uranus and Neptune are composed primarily of methane, ammonia and water, with an outer envelope of hydrogen and helium. All the gas giant planets share a characteristic that differentiates them from the inner rocky planets. They all have rings and numerous moons orbiting them.
Jupiter- the largest planet in the solar system- is around 300 times more massive than the Earth. It´s composed of approximately 90 percent hydrogen (H), 9 percent helium (He) and 1 percent traces of other elements. These gases become liquid with increasing pressure and temperature. Liquid hydrogen at its core behaves like a molten metal with free electrons conducting electricity, creating Jupiter´s magnetosphere. Its rocky core is believed to be of a diameter the size of the Earth. More than 60 moons orbit Jupiter, including the Galilean moons: Ganymede, Calisto, Io and Europa.
Jupiter can be easily observed during a cloudless, moonless night with a small telescope, including the bands across its atmosphere and the Great Red Spot, which is a swirling hurricane of about twice the size of the Earth.
Saturn is the second largest planet in the solar system and the sixth planet from the Sun. The atmosphere of Saturn is similar to the one on Jupiter with about 92.4 percent hydrogen and 7.4 percent helium, with traces of ammonia and methane. Its internal, metallic hydrogen layer is thinner than Jupiter´s, while its core might be larger. Saturn´s internal pressure and temperature are less extreme than in Jupiter. The rapid rate of rotation and the conductive metallic hydrogen in Saturn´s core are thought to generate its magnetic field. Saturn´s ring system consists of nine rings composed mainly of ice, dust and rocks. 62 known moons orbit the planet. Saturn can be easily observed with the naked eye during moonless, clear nights, but a four-inch aperture telescope will enable you to observe Saturn´s rings and moons.
Uranus is believed to have a rocky core similar in size to Jupiter´s, surrounded by a layer of water clouds and ammonia. Spectroscopic studies have revealed that Uranus contains about 82 percent hydrogen and 14 percent helium in its atmosphere, with about 2 percent methane and 1 percent ammonia, along with traces of hydrocarbons. Methane absorbs red light and reflects blue, which is what gives Uranus a blue-green color. Uranus has a ring system, a magnetosphere and various moons, like the other gas giants. Its axis of rotation is tilted 98º sideways, resulting in extreme seasonal conditions at the poles, with 42 years of continuous sunlight, followed by another 42 years of continuous darkness at the other pole.
Neptune is the eighth farthest planet from the Sun. Neptune is the most dense gas giant, with about 17 times the mass of the Earth. Neptune was discovered on September 23, 1846, due to variations in the orbit of Uranus, which led astronomers to the prediction of another planet in its vicinity. Neptune´s outer envelope is composed primarily of hydrogen and helium, while methane and ammonia constitute most of its interior. There are traces of hydrocarbons, as well. Neptune´s core is composed principally of ices and rock. The small quantities of methane give Neptune its bluish appearance. Neptune has one of the coldest temperatures, -218 ºC (55 K), in the solar system.
Among the gas giant, Jupiter is the planet that astronomers refer to as a model to the rest of the Jovian planets.
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| Public Domain via Wikimedia commons |
Tuesday, May 26, 2015
Big Distances in the Universe (Light years, parsecs, paralax)
Measuring distances is very important, so as to know the physical characteristics of an
object, for instance, the width of a street, the height of a building,
or the area of a lake. To measure distances on earth, man makes use of
units of measurement, such as centimeters, meters, kilometers, miles
etc. However, in the vast spaces between stars, such units arenot adequate. To measure big distances in outer space, it is necessary to
find other reliable methods. Astronomers utilize units of measurement,
such as the astronomical unit (AU), the parallax method, the parsec, and
the light year.
The astronomical unit (AU):
To measure distances within the solar system, astronomers make use of the astronomical unit (AU) which is the distance that separates the earth from the sun (159 million kilometers;). Mercury is 0.390 AU (58 million km) from the sun, Venus is 0.72 AU (108.2 million km) from the sun, Mars is 1.5 AU (228 million km) from the sun, Jupiter is 5.2 AU (778 million km) from the sun, Saturn is 9.5 AU; Uranus is 19 AU; Neptune is 30 AU; and Pluto is 39 AU from the sun. Eris, which is a dwarf planet, is approximately 68 AU from the sun.
The method of trigonometric parallax:
The method of trigonometric parallax is based on the fact that a small triangle can be related to a big triangle, thus using the AU as the base of the triangle, the angles which are formed can be measured. If one star is observed against the background of other stars on July the 14th and the same star is observed six months later (January the 14th) against the background of other stars when the earth will have traveled right to the other side of the sun, the star will seem to have moved with respect to the background stars in what is known as stellar parallax.
Using this movement and some trigonometry, the parallax angle, which corresponds to a small shift in apparent position in the celestial sphere, can be measured and the rules of trigonometry can be used to determine the distance to the star. Trigonometric parallax permits to measure distances directly by measuring the parallaxes of nearby stars. The parallax of Proxima Centaury is 0.742 arcs seconds = 278.46 AU. In the 1990´s the hipparcos satellite measured parallaxes with a precision of a thousand of an arc second for one hundred thousand stars.
The parsec:
Unfortunately, ground-based telescopes can only measure parallaxes for stars that are a few hundred light years. Telescopes in orbit around the earth are able to measure smaller parallaxes and consequently greater distances; nevertheless, the most distant stars for which parallax can be determined are just a few thousand light years away.
Another unit of distance derived from parallax is the parsec which is short for parallax second. The parsec if equal to 1/ parallax in arc seconds. When the parallax angle of a star measures one arc second, which is equivalent to one sixteenth of an arc minute which in turn equals one sixteenth of one degree, the distance to the star is one parsec. One parsec is equivalent to 206,265 AU. Proxima Centaury is 0.742 arcs seconds = 1.35 parsecs = 278,457 AU.
The light year:
The light year is the distance that the light travels in one year at a speed of 300,000 km/sec. One light year is equivalent to 63, 270 AU or 0.31 parsecs. A beam of light would take 1 ¼ of a second to cross the orbit of the moon; four hours to reach the planet Neptune; and 4.4 years to reach the nearest star (proxima centaury). To obtain the distance of a star in light
years, it is necessary to first measure the parallax, turn it into parsecs and then multiply the parsecs by 3.26.
Fifty million light years separate the earth from the galaxy M87 in the Virgo cluster. The Milky Way galaxy is approximately 100,000 light years in diameter. The Milky Way galaxy is 100,000 light years across. The Virgo cluster is about 59 megalight years away. The distance from the earth to the edge of the visible universe is approximately 46.5 gigalight years.
The cosmic distance ladder (extragalactic distance scale) is a series of methods that astronomers use today to determine the distances of astronomical objects beyond the Milky Way galaxy, which are not easily obtained with conventional methods. Some of these methods make use of the properties of these objects, such as its luminosity. A direct distance measurement is only possible for objects that are within 100 parsecs, for objects that are further beyond, it is necessary to associate the methods that provide close distances with methods that make available larger distances.
The astronomical unit (AU):
To measure distances within the solar system, astronomers make use of the astronomical unit (AU) which is the distance that separates the earth from the sun (159 million kilometers;). Mercury is 0.390 AU (58 million km) from the sun, Venus is 0.72 AU (108.2 million km) from the sun, Mars is 1.5 AU (228 million km) from the sun, Jupiter is 5.2 AU (778 million km) from the sun, Saturn is 9.5 AU; Uranus is 19 AU; Neptune is 30 AU; and Pluto is 39 AU from the sun. Eris, which is a dwarf planet, is approximately 68 AU from the sun.
The method of trigonometric parallax:
The method of trigonometric parallax is based on the fact that a small triangle can be related to a big triangle, thus using the AU as the base of the triangle, the angles which are formed can be measured. If one star is observed against the background of other stars on July the 14th and the same star is observed six months later (January the 14th) against the background of other stars when the earth will have traveled right to the other side of the sun, the star will seem to have moved with respect to the background stars in what is known as stellar parallax.
Using this movement and some trigonometry, the parallax angle, which corresponds to a small shift in apparent position in the celestial sphere, can be measured and the rules of trigonometry can be used to determine the distance to the star. Trigonometric parallax permits to measure distances directly by measuring the parallaxes of nearby stars. The parallax of Proxima Centaury is 0.742 arcs seconds = 278.46 AU. In the 1990´s the hipparcos satellite measured parallaxes with a precision of a thousand of an arc second for one hundred thousand stars.
The parsec:
Unfortunately, ground-based telescopes can only measure parallaxes for stars that are a few hundred light years. Telescopes in orbit around the earth are able to measure smaller parallaxes and consequently greater distances; nevertheless, the most distant stars for which parallax can be determined are just a few thousand light years away.
Another unit of distance derived from parallax is the parsec which is short for parallax second. The parsec if equal to 1/ parallax in arc seconds. When the parallax angle of a star measures one arc second, which is equivalent to one sixteenth of an arc minute which in turn equals one sixteenth of one degree, the distance to the star is one parsec. One parsec is equivalent to 206,265 AU. Proxima Centaury is 0.742 arcs seconds = 1.35 parsecs = 278,457 AU.
The light year:
The light year is the distance that the light travels in one year at a speed of 300,000 km/sec. One light year is equivalent to 63, 270 AU or 0.31 parsecs. A beam of light would take 1 ¼ of a second to cross the orbit of the moon; four hours to reach the planet Neptune; and 4.4 years to reach the nearest star (proxima centaury). To obtain the distance of a star in light
years, it is necessary to first measure the parallax, turn it into parsecs and then multiply the parsecs by 3.26.
Fifty million light years separate the earth from the galaxy M87 in the Virgo cluster. The Milky Way galaxy is approximately 100,000 light years in diameter. The Milky Way galaxy is 100,000 light years across. The Virgo cluster is about 59 megalight years away. The distance from the earth to the edge of the visible universe is approximately 46.5 gigalight years.
The cosmic distance ladder (extragalactic distance scale) is a series of methods that astronomers use today to determine the distances of astronomical objects beyond the Milky Way galaxy, which are not easily obtained with conventional methods. Some of these methods make use of the properties of these objects, such as its luminosity. A direct distance measurement is only possible for objects that are within 100 parsecs, for objects that are further beyond, it is necessary to associate the methods that provide close distances with methods that make available larger distances.
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| By Azcolvin429 CC-BY-SA-30 via Wikimedia Commons |
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