One is called Nautical, another one is called Astronomical
135835
Civil twilight is when the sun is between 0 and 6 degrees below the horizon.\nNautical twilight is when the sun is between 6 and 12 degrees below the horizon.\nAstronomical twilight is when the sun is between 12 and 18 degrees below the horizon.
557160
Two I have seen are AU where 1 AU or Astronomical Unit is the distance between the Earth and Sun, and LD which is the Lunar Distance, approx 250000 miles.\n\nLargest? Parsec: A unit of astronomical length based on the distance from Earth at which stellar parallax is one second of arc and equal to 3.258 light-years, 3.086 × 10^13 kilometers, or 1.918 × 10^13 miles.
330772
True. It is called the coriolis effect. It causes moving objects to drift sideways on their courses. This causes hurricanes to rotate. In the Northern hemisphere, the shift is to the right, in the Southern hemisphere it is to the left.
84694
I think you are looking for astrology not astronomy.
9613
Astrology is not considered to be a science, but is more appropriately an art, and is separate from astronomy, the scientific study of outer space. The calculations performed in astrology involve arithmetic and simple geometry and serve to locate the apparent location of heavenly bodies on desired dates and times based on tables constructed by astronomers. There have been astrologers who claim to try to put astrology on a sound scientific basis, but for most it is an art that merges calculations with their own intuitive perceptions. For most astrologers the purported relationship between the celestial bodies and events on earth need not be causal, nor even scientific.
106062
A clock and a sundial?
276331
It is called an ANAEROID BAROMETER
605908
The only way that the two ships would have the same orientation or definition of up is if they are using a common reference system.  Astronomers use a galactic coordinate system that is based on the fact that most of the galaxies lie close to a plane.  In 1959, the galactic coordinate system was defined based on the orientation of the Milky Way creating a common "north" or "up" reference that is used to define the location of astronomical bodies.\n\nWhen we eventually get to the point that we have multiple spaceships travelling through regions of space away from reference points such as planets, there will likely be a common reference system in place that will tell the ships and their crews which way "up" is.
182799
Not his original, but the image in the middle of the first link I'm listing is pretty close to Descartes' from De Meteorologica.  The second source has several modern takes on the image as well as a nice physical explanation of what is going on.
87298
The seas, ocaena, rivers, and lakes of the world are all composed of similar material to different degrees. For example the Atlantic, Pacific and Indian Ocean all have different amounts of salt in them. When the Panama canal was built a division between the regions was seen. Not so much with eyes but with equipment. True, those who named regions of water may not have had any idea that they were slightly different but they are. On a ship it'll be pretty hard to tell which ocean you're in if you awoke from a concussion and just stared out at sea. Maritime borders are only used as a political tool. Every second some of teh ATlantic mixes with the Pacific and vice versa.
84732
1)In the space there is no direction.So it matters not what direction you call by what name.\n2) On the Earth , on the other hand , it does matter and matters a lot; and the reasons are too obvious to quote.\n3) On the earth the bearings are taken with the help of fixed stars in the Sky and it has no racial bias.\n4) In this context the POLAR STAR acquires importance. The North pole of the earth is directly pointing towards this unmoving star in the sky. So much so that if you are standing exactly on the north pole, the Pole star or the North Star will be directly above you and the angular distance between you and the star will be Zero. That is exactly how the polar expedition leaders find out if they have reached their goal correctly or not.\nAs you move towards the South pole the angular distance increases to reach 180 degrees and the pole star disappears from your sight.
222798
NORTHERN HEMISPHERE CONSTELLATIONS -\nhttp://cybnet.co.za/northern.htm\n\nSOUTHERN HEMISPHERE CONSTELLATIONS -\nhttp://www.vb-tech.co.za/southern.htm
330875
North and south geographic poles. A compass points towards the North magnetic pole, which is why you must correct for your magnetic declination to find true north using a compass. \n\nSince probably 1000 AD, navigation, however has relied on watching the skies more than watching a compass. Therefore, due north or south  is always the direction to that point in the sky that all the stars circle, projected down to the surface of the earth, and those positions in the sky are projections of the geographic pole (Polaris is actually about 0.8 degrees off the north celestial pole. If north was based on polaris, north would change by as much as 1.6 degrees depending on what time it is!)
538937
One answer = B or D\n\nTwo answers = Both B and D.\n\nCyclones in the northern hemisphere rotate counter-clockwise (coriolis effect) and as part of the rotation of a "low" pressure system, the surface currents, being wind driven and rotating in a counter-clockwise fashion, will cause a convergence at the center of lowest pressure inducing an upwelling of the sea surface. \nUpon landfall this is seen as "storm surge"
17123
Many of the obvious celestial bodies have names which are carried over from tradition and history.  Examples include Terra (the Earth), Luna (the moon), Sol (the sun), Neptune, Venus, Mars, etc.  You'll note many of these carry the names of Greek gods.  However, today the International Astronomical Union uses a variety of naming conventions to assign proper names to the objects in our universe.  When a new object is observed, the Union uses its rules to name it so that scientists around the world can use a 'common language' when discussing it.  Examples of star names include Polaris (the North Star, located at the Celestial North Pole), Proxima Centauri (the closest known star) and Wolf 359, a real star system that was chosen as the site for a legendary battle with the Borg in the 'Star Trek' universe.  You might read the link in the 'sources' section for more information.\nPS: Websites that let you 'name a star' are purely cosmetic and the assigned names are in no way recognized by the Union or printed in academic star charts.  You would be better off using a desktop publishing program and designing a nice 'plaque' yourself if you wanted to make a gag gift.
62651
Many. They are called orreries. There is one on the internet too (see reference). The first reference has a picture of one at the Smithsonian. \n\nBefore the orrery, there was something similar called the armillary sphere, invented by Eratosthenes (aka spherical astrolabe, armilla, or armil).\n\nThe tellurian is similar to orrery. Sometimes an orrery was called a planetarium.
194604
this is not a question about astronomy.\n\nhttp://en.wikipedia.org/wiki/astronomy