Polar Star is probably one of the most frequently mentioned bodies.To talk about it in the pages of fiction, in the notes of seafarers, research and development.His fame even popular star is obliged primarily to that which shows the direction of the North Star.Its unique position for several hundred years of helping travelers navigate both by sea and by land.Moreover, it plays a role in determining the distances to the expanse of space, and is therefore the subject of numerous scientific studies.But first things first.
Dancing Stars
answer to the question, which shows the direction of the North Star, is inextricably linked to place luminaries on the imaginary celestial sphere.If you watch the stars from Earth, it seems as if they are moving around the planet, then sinking below the horizon, it is surfacing again.The images taken by the camera with a slow shutter speed, you can see that the light moved on circular paths of different diameter.What they are smaller, the closer to the pole star of the celestial sphere.In the center of the circles formed by the movement of the stars in the Northern Hemisphere is a fixed point.This is the North Star, or, as it was called some people, North nail, funny star, or Heavenly Iron Count, Gold Pile.
Features provisions
Metaphor "nail" very well: if we continue imaginary metal rod from the "cap" is easy to understand which direction shows the North Star.This "nail" pierces the globe precisely at the North Pole, passes through all the inner layers of the planet and appears again at the South Pole.Thus, the North Star in the sky is located on the extension of the Earth's axis.From the North Pole it separates smaller 1ยบ.
should be noted that the North Star is moving in the same way as the rest of the luminaries.It is apparent to us recorded is connected with the place location on the continuation of the axis.It is actually quite a rapid movement of the stars is due not only to their own movement, but also the rotation of the planet.Making turns around its axis, the Earth turns to the stars is one, then the other side.And only light above the poles, always see the same part of the surface.By the way, at the South Pole also has a Polar Star - Sigma Octantis, but it is very faint compared to the other.However, after some time, things can change.
Post passed - the post took
North Star shows the direction to the north from the year 1100 AD.It will be as close to the pole of the world only in 2100, and then pulls away.So, from the beginning of time as head pointer is passed from one light to another.This is due to the proper motion of stars, as well as the phenomenon of the precession of the Earth's axis.Imaginary rod piercing the planet, is also moving: he slowly circled.The reason lies in the peculiarities of the form of the globe and the force of gravity.Axis takes one lap for nearly 26,000 years.
About 15 thousand years ago in the role of the Northern Nail acted Vega, the brightest point of the constellation Lyra.And after a little less than 11 thousand years, she again takes this position.In place of the North Star in the near future will Alrai (Gamma Cephei), it will be in the year 3200.In 5000, the Beta Alrai replace the same constellation Alfirk, and then, in 6500-m - Alderamin (Alpha Cephei).Between 8,500 and 13,000 years, the position of the Pole Star will take and Deneb in the constellation Cygnus Sadr.
How to find the North Star?
associated with North highlight one very persistent myth generated by its fame and popularity.It seems that the star that everyone's lips should be, if not the brightest in the sky, at least eclipsing many others.However, it is not.Polar Star is located in the constellation Ursa Minor and among the other stars in its structure really stands out.In the list of the most striking points of the entire night sky, it takes only 46th place.It is therefore important to know how to find the North Star.
main landmark - is the Big Dipper.Constellation is familiar to almost all with children.To detect the Northern Nail need to mentally connect the same line two end stars of the Big Dipper - Dubge and Merak.If you continue the line by a distance approximately equal to the five intervals between Dubge and Merak, then it will show end and the North Star.It is crowned by a tail of Ursa Minor.
How to navigate the terrain of the North Star?
Since then, as the North nail was in the vicinity of the poles of the world, it was used as a convenient guide.North Star indicates the direction of the north, and even more accurate than a compass.Identify the points of the compass at the same time simple enough.It is necessary to drop a perpendicular to the surface of the North Star.If you stand to face him, then south would definitely behind, east - on the right, the west - on the left.
Moreover Polaris shows the direction to the north, it is also an indication of the geographical latitude.In order to determine need to measure the height of the lights on the horizon.The lower the value, the closer to the equator.At the North Pole the Polar Star is located at the zenith.At the equator, as it almost merges with the horizon.That determining the angle between the North Star and the horizon in the direction of the north, the sailors of the past century to navigate the terrain, paved and adjust your route.
On other planets
In the vastness of space has many similarities to our North Star.The rotation axis is an inherent property of all the planets, but because if you watch the movement of the stars with their surface, easy to find fixed points, indicating the North and South poles.For Mercury, for example, the polar star - Omicron Ophiuchi, its southern counterpart - Alpha constellation Painter.Is North nails and the Moon - a Delta Doradus.
value for astronomy
North Star, or Alpha Ursa Minor, has a whole range of features that make it unique.Among them - the periodic pulsations, allowing light to be attributed to the class of Cepheids.They are characterized by brightness changes, temperature, and size.The period of pulsation of the North Star - 3.97 days.In this light variation from the Earth invisible.
Studies have shown that there is a link between the pulsation period of Cepheids and luminosity.It was found that the longer the period, the greater and luminosity.This ratio is used in astronomy to determine the distance to the remote object.And as the North Star - the closest to the solar system Cepheid, its role in the calculations can not be overestimated, especially when you consider that with increasing distance from the star of the periodic data accuracy is reduced.
Custom
This property of the North Star riveted the attention of many researchers.During the study it became known that North nail - Cepheid difficult.Its ripples are characteristic: they gradually die out.At the end of the last century was common assumption is that in the early 2000s, star may cease to be a Cepheid, which has never happened in the history of science.However, this did not happen: in 1993, changes in the amplitude fluctuations suspended.In addition, during this time the star became brighter by 15%.
Cosmic Infinity
to determine the distance to distant objects use data on the luminosity and the location of all nearby Cepheids.Using this method, in the first quarter of the last century, the famous Edwin Hubble determined the distance to the Andromeda nebula, and proved the existence of other galaxies.Today, based on the methodology to calculate the size of many stellar "Commonwealth".It is based on the extent of the current understanding of the universe.
small "but"
catch is that to date there is no general consensus on the distance up to the North Star.The accepted figure is 400 with a small light-years, received satellite "Hipparcos" in 1990.However, at the beginning of this century, this estimate underwent changes: first, it was reduced to 330, then increased to 359 light-years.Finally, in 2012, David Turner put forward a new suggestion - 323 light-years.
As already noted, the North Star - the closest to the solar system Cepheid.With the decrease or increase the distance to it, and changes our understanding of the cosmic scale.Reducing the value of not only making a little closer stars and galaxies, but also affects the assessment of the size of the universe.Clarification of the distance to the North Star will make its own changes in the understanding of the scale of the cosmos, make overestimate the value of the mass of dark matter, could lead to a review of some aspects of the theory of the expanding universe.
Astronomical features
That shows what direction the North Star, in general, depends little on some of its space characteristics.However, they can be said to compensate for modesty shine so important for land navigation lights.
Polar Star is brighter and more sun.It belongs to a class of supergiants, it has a radius greater than the sun 46 times.Northern Nail Luminosity 2500 times greater than the similar parameter of our star.
But that's not all: not a single Pole Star.It is part of a system of three stars, which differ in size and brightness.A Pole - center of the system, the same supergiant on the impressive distance away is the Polar B. This star is much smaller and its weight - only 1.39 Solar (mass of Polaris A - 4.5 solar).Very close to the supergiant is his companion, Polaris Ab (1,26 solar masses).Due to the small distance separating the two luminaries, "the humble companion" for a long time could not detect.He managed to get an image only with a telescope "Hubble".
turns out, not only that which shows the North Star, makes it unique in the sky.Custom Cepheid and triple system, it occupies the minds of many astronomers.And it looks very symbolic.For a long time in the history of the direction of the North Star (indicate its path) to help navigate through the night across the ocean, or in an unfamiliar area.
Today, instead of natural indicators still often use different tools and gadgets, Polaris is a landmark in space.Although North nail in his new role does not indicate the direction and distance helps determine its value and importance to man and science as a whole is not reduced.And because the researchers are working on the precise definition of how the North Star was removed from the Sun why it fades ripple, and do not disregard this little nondescript, and even, in the opinion of a simple observer on earth, the star.
