Celestial pole - Celestial pole The two celestial poles are the imaginary points where the Earth's spin axis intersects the celestial sphere. The sky appears to drift overhead from east to west, completing a full circuit around the sky in 24 (sideral) hours. This phenomenon is due to the spinning of the Earth on its axis. The Earth's spin axis intersects the celestial sphere at two points. These points are the celestial poles. As the Earth spins, they remain fixed in the sky, and all other points seem to rotate around them. The celestial poles are also the poles of the celestial equatorial coordinate system, meaning they have declinations of +90 degrees and -90 degrees (for the north and south celestial poles, respectively). The north celestial pole currently has.
Celestial sphere - Celestial sphere In astronomy and navigation, the celestial sphere is an imaginary rotating sphere of "gigantic radius", concentric with the Earth. All objects in the sky can be thought of as lying upon the sphere. Projected, from their corresponding terran equivalents, are the celestial equator and the celestial poles. Many ancient societies believed that the stars were equidistant from the Earth and that this sphere was a real model of the universe. This model is a useful abstraction, but not correct. Everything we see in the sky is so very far away, that their distances are impossible to gauge just by looking at them. Since their distances are indeterminate, you only need to know the direction toward the object to locate it in the sky. In.
Celestial navigation - Celestial navigation Celestial navigation was the first system devised to help sailors locate their positions accurately on a featureless ocean. Celestial navigation is based on angular measurements, typically measured between the horizon and a common celestial object, like the Sun, the Moon or known stars and planets. The basic concept of celestial navigation is that, at any given instant, any particular celestial object will be directly over some geographical position on the Earth. By measuring the actual angle to that object, and knowing the spot where that object is actually above, your own position relative to that known spot can be calculated. This "fixes" you on a circle of that angle around the spot, and several such measurements are taken to find the intersection of the.
Pole - Pole A magnetic pole is an end point of a magnet. The poles of the Earth, or other planet, are the points where its axis of rotation passes through its surface. See: geographical pole, North Pole, South Pole, polar region. The celestial poles are the ends of the celestial sphere. A pole is a long and straight stick, usually vertical or intended to be used vertically. See barber, pole vault, pole (object). In complex analysis, a pole of a function is a certain simple type of singularity. See pole (complex analysis). A pole is also a unit of length, also called a rod, equal to 5.5 yards or 16.5 feet (5.029 meters in SI units), see pole (length). A Pole is a native of Poland. See.
North Pole - North Pole The North Pole, the northernmost point on the Earth, can be defined in four different ways. Only the first two definitions are commonly used. However it is defined, the North Pole lies in the Arctic Ocean. The Geographic North Pole, also known as True North, is the northernmost point on the Earth as determined by the planet's rotation. It has a known fixed position, at latitude 90° North. The boundaries of Canada extend all the way to the Geographic North Pole. There is no land at this location, which is usually covered by sea ice. The Magnetic North Pole is the northern point at which the geomagnetic field points vertically, i.e. the dip is 90°. This definition was proposed by Sir William Gilbert, a courtier.
Horizontal coordinate system - coordinate system The horizontal coordinate system is a celestial coordinate system that uses the observer's local horizon as the fundamental plane. This conveniently divides the sky into the upper hemisphere that you can see, and the lower hemisphere that you can't (because the Earth is in the way). The pole of the upper hemisphere is called the zenith. The pole of the lower hemisphere is called the nadir. The angle of an object above or below the horizon is called the altitude (Alt for short). The angle of an object around the horizon (measured from the North point, toward the East) is called the azimuth. The horizontal coordinate system is sometimes also called the Alt/Az coordinate system. The horizontal coordinate system is fixed to the Earth, not the stars. Therefore, the.
Flag of Brazil - before). Actually, the current Brazilian Flag was inspired at the old Imperial Brazilian Flag. The two flags are almost identical, and the Green color represents the Bragança Royal Family of Pedro I, the first Emperor of Brazil; and the Yellow color representing the Castela e Lorena Royal Family of Leopoldina, Pedro's wife. The difference between the old Imperial Flag and the current Republican flag is the Royal Coat of Arms, that was substituted by the blue circle, which is a portrait of the sky over Rio de Janeiro on the morning of November 15, 1889 -- the day of the Declaration of the Republic. It is represented as seen from outside of the celestial sphere (i.e. the view is mirrored). Each of the 27 stars represents a different state and the.
Ursa Minor - constellation in the northern sky, whose name means the "Lesser Bear" in Latin. It is one of the 88 modern constellations, and was also one of the 48 listed by Ptolemy. It is notable as the location of the north celestial pole, although this will change after some centuries due to the effects of precession. Table of contents showTocToggle("show","hide") 1 Notable features 2 Mythology 3 History Notable features Ursa Minor contains an asterism colloquially known as the "Little Dipper" because its brightest stars seem to form a ladle, or dipper shape. The star at the end of the dipper handle is Polaris, the "North" or "Pole Star". Polaris, can also be found by following a line through the two stars which form the end of the "bowl" of the Big Dipper,.
Declination - the equatorial coordinate system. Dec is comparable to latitude, projected unto the celestial sphere, and is measured in degrees north of the celestial equator. Therefore, points north of the celestial equator have positive declination, while those to the south have negative declination. Clarification An object on the celestial equator has a dec of 0°. An object above the north pole has a dec of 90°. An object above the south pole has a dec of -90°. See also: right ascension Declination is used in some contexts that rule out astronomical declination, to mean the same as magnetic declination. Declination is occasionally and erroneously used to refer to the linguistic term declension..
Alrai - is the naked-eye star that will follow Polaris as the Earth's northern pole star, due to the precession of the equinoxes. Alrai will become closer to the northern celestial pole than Polaris in approximately 3000 AD, and be at its closest approach around 4000 AD. The "title" will pass to Iota Cephei some time around 5200 AD. It is a K1 III-IV class star, approximately 50 light years away. It is of magnitude 3. Its name derives from the Arabic Al-ra'i, meaning "the shepherd". Note that the star Beta Ophiuchi is sometimes also called Alrai, but it is more commonly known as Celbalrai or Kelb Alrai..
Capella - inhabited northern latitudes and the sixth-brightest star in the sky. It is closer to the north celestial pole than any other bright star (Polaris is quite dim by comparison) and as a result has played a significant role in many mythological writings. A tablet dating back to 2000 BC refers to Capella. Astrologically, Capella portended civic and military honors and wealth. Astronomically, Capella's interest lies in the fact that it is an easily-studied spectroscopic binary star with a period of 104 days. It is a giant G-class star. (You may be looking for A cappella, a term in music.).
Cassiopeia (constellation) - was the wife of Cepheus and the mother of Andromeda. It is one of the 88 modern constellations, and was also one of the 48 listed by Ptolemy. Notable features Five of the stars of Cassiopeia form a W shape, which is one of the most distinctive patterns in the northern sky. Since it is close to the north celestial pole, it remains in the sky all night long in most northern countries. It is frequently used as a rough indicator of sidereal time; the leading bright star of the W, β Cassiopeiae, called Caph, lies almost at zero hours right ascension and hence a line drawn through Polaris and β Cassiopeiae must pass close to the vernal equinox. The hour angle of this line must be equal to sidereal time..
Circumpolar star - those stars which are located near the poless of the celestial sphere. As the Earth rotates, the sky appears to rotate; and most stars will be hidden below the horizon at some point in their circular paths. If, from a certain location, a star is near enough to the celestial pole that it never appears to go "under the horizon"; it will therefore be visible (from said location) for the entire night, on every day of the year. Some of the most circumpolar stars do not seem to engage in diurnal motion, at all. Such a definition implies that different stars can be defined as circumpolar at different Earth latitudes. For example, to an observer place right at the Earth's North or South Pole, virtually all the stars are circumpolars. For.
Crux - the most famous. It is surrounded on three sides by the constellation Centaurus while to the south lies the Fly (Musca). Table of contents showTocToggle("show","hide") 1 Notable features 2 Notable deep sky objects 3 History Notable features With the lack of a significant pole star in the southern sky (σ Octantis is closest to the pole, but is so faint as to be useless for the purpose), two of the stars of Crux (Alpha and Gamma, Acrux and Gacrux respectively) are commonly used to mark south. Following the line defined by the two stars for approximately 4.5 times the distance between them leads to a point close to the Southern Celestial Pole. Alternatively, if a line is constructed perpendicularly between α Centauri (Toliman) and β Centauri, the point where the above line and.
Cruising - distant bank can be painful, sometimes taking up to 3 weeks for a check or letter-of-credit to clear. It helps to be in a large city, and bank at a large bank in a famous city of your home country. Get money no more often than every six months, as small, $10 traveler's checks. Perform haul-outs, bottom painting and other maintenance while waiting for the money. Also, plan to wait somewhere pleasant and inexpensive. How to start Try it out in little steps. Many people are attracted to the romance of cruising, but find that they dislike the reality. First, take a class in sailing. This will teach you the basics, and you'll see if you like to sail at all. Next, buy a small dinghy (6-11 feet) with sails. Sail.
Zenith - when you look 'straight up' from the ground. More precisely, it is the point on the sky with an altitude of +90 Degrees; it is the pole of the horizontal coordinate system. Geometrically, it is the point on the celestial sphere intersected by a line drawn from the center of the Earth through your location on the Earth's surface. The zenith is, by definition, a point along the local meridian. This article originates from Jason Harris' Astroinfo which comes along with KStars, a Desktop Planetarium for Linux/KDE. See http://edu.kde.org/kstars/index.phtml This word can also be referring to Zenith Electronics Company or Zenith Data Systems. Zenith is also the fictional town that forms the setting for Babbitt, Arrowsmith, and other novels by Sinclair Lewis. It is located in the fictional state of Winnemac,.
True north - is a navigation term referring to the direction of the North Pole relative to the navigator's position. True north is compared to: Magnetic North Grid north The direction of true north is marked in the skies by the celestial north pole. For most practical purposes, this is the position of Polaris. However, due to the precession of the Earth's axis, true north rotates in an arc that takes approximately 25,000 years to complete. Currently, in 2002, Polaris is at its closest approach to the celestial north pole. 2,000 years ago, the closest star to the celestial north pole was Vega. On maps issued by the United States military, the U.S. Geographical Survey, and the U.S. Navy, true north is marked with a line terminating in a five-pointed star..
Season - the seasons. Note that, regardless of the time of day (i.e. the Earth's rotation on its axis), the North Pole will be dark, and the South Pole will be illuminated; see also arctic winter. In addition to the density of incident light, the dissipation of light in the atmosphere is greater when it falls at a shallow angle. Fig. 2 As the Earth revolves around the Sun, the seasons in the northern and southern hemispheres are opposite. A season is one of the major divisions of the year. Typically, the year is divided into four seasons: spring, summer, autumn (fall), and winter. Some cultures may have a different number of seasons; for instance, some indigenous peoples in Australia's Northern Territory use six seasons. In tropical regions it is common to speak.
Sundial - Most honest sundials are made to 45 degrees north. A sundial can be adjusted to another latitude by tilting it so its gnomon(s) is (are) parallel the Earth's axis of rotation. That is, the end of a gnomon should point at the north celestial pole in the northern hemisphere, or the south celestial pole in the southern hemisphere. A sundial can be rotated around its gnomon (which must still point at the celestial pole) a maximum of 7.5 degrees to the east or west to adjust to the local standard time zone (time zones are 360 degrees/24 hours = 15 degrees wide). Tilt the sundial so that it is oriented as if it were at the longitude of the center of your local time zone. To correct for daylight savings time,.
Palomar Observatory - to 1957). This survey was performed using (14 inch)2 or (6 degree)2 photographic plates in both blue and red (separately) on the 48 inch Schmidt reflecting telescope. The survey covered the sky from a declination of +90 degrees (celestial north pole) to -24 degrees (plate centers) and all right ascensions and had a sensitivity to +22 magnitudes. Until the completion of the Two Micron All Sky Survey (2MASS), POSS was the most extensive all-sky survey ever. When completed, the Sloan Digital Sky Survey will surpass both. POSS also exists in digitized form (i.e., the photographic plates were scanned), as the Digital Sky Survey (DSS) [1]. Current research One of the current ongoing research programs at Palomar is Near-Earth Asteroid Tracking. External Links Caltech Astronomy The SBO Palomar Sky Survey Prints This.
