Difference between revisions of "Astronomy"

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== Vernal and Autumnal Equinox ==
 
== Vernal and Autumnal Equinox ==
  
The point in time when the tilt of the earth is at a 90 degree angle with the sun and the sun is exactly above the equator at a 90 degree angle is called an equinox.  At high noon at the highest sun peak of the day the sun should be at exactly south.  This is also the median of the day between sunrise and sunset.  Photographing the sun for a year every day and showing the path of the sun is called an [http://http://antwrp.gsfc.nasa.gov/apod/ap061223.html analemma] and where the path of sun crosses itself is where the equinoxes cross.  Vernal Equinox is on March 20th, and Autumnal Equinox is on September 23rd.
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The point in time when the tilt of the earth is at a 90 degree angle with the sun and the sun is exactly above the equator at a 90 degree angle is called an equinox.  At high noon at the highest sun peak of the day the sun should be at exactly south.  This is also the median of the day between sunrise and sunset.  Photographing the sun for a year every day and showing the path of the sun is called an [http://antwrp.gsfc.nasa.gov/apod/ap061223.html analemma] and where the path of sun crosses itself is where the equinoxes cross.  Vernal Equinox is on March 20th, and Autumnal Equinox is on September 23rd.
 
 
  
 
== The Sky Sweeper ==
 
== The Sky Sweeper ==

Revision as of 13:15, 12 March 2007

Astronomy is the study and graphing/plotting of skyward objects such as stars, planets and other object that are found in our heavens. Astronomy also is important for timekeeping and global positioning when all electronics fail. Since the earth is a sphere rotating around a star and itself spinning, simple geometry can help figure out ones position globally.

Summer/Winter Solstice

The Solstice indicates an extreme point in the elevation of the sun relative to the viewing horizon. The earth is tilted 23.45 degrees and the tilt is fixed into a certain direction in space. As we complete an orbit around the sun the sun at high noon will appear to shift higher and lower. The highest point is called the summer solstice and the lowest point the winter solstice. It is vice versa south of the equator (australia for example). Summer solstice is usually on June 23rd and Winter Solstice is usually on December 20th.

Vernal and Autumnal Equinox

The point in time when the tilt of the earth is at a 90 degree angle with the sun and the sun is exactly above the equator at a 90 degree angle is called an equinox. At high noon at the highest sun peak of the day the sun should be at exactly south. This is also the median of the day between sunrise and sunset. Photographing the sun for a year every day and showing the path of the sun is called an analemma and where the path of sun crosses itself is where the equinoxes cross. Vernal Equinox is on March 20th, and Autumnal Equinox is on September 23rd.

The Sky Sweeper

You could use a fisheye lens to map the entire path of the sun with a webcam. But if you mistrust sillycon (glass) and want to approach the problem from the perspective of a honeybee then perhaps the following idea may work for you as posted on the [centroid.eu blog/xlog].

Imagine the following scenario. The earths magnetic field fails and navigation systems on cars, airplanes and ships fail, when they don't rely on GPS. Or instead of failing the poles reverse direction for the entire earth. This scenario was predicted by some scientists who I read were studying the moving north pole in northern Canada. How do you get an exact bearing? I have thought of a machine that can track objects such as the sun and the moon across the entire sky and determine their angle, and do this relatively cheap.

File:Sky-sweeper.jpg

As you can see there is 2 axiis. One can be a used turntable/record phonograph that spins at 33 revolutions per minute. The other could be a bike wheel with a mounted USB camera which serves 30 frames per second. There is two permanent light sources that the camera passes these are mounted at a known angle (preferably 90 degrees) to any axis. As the camera passes these light points it knows exactly how long a full revolution (or period) will take, a computer connected to the USB cable records this. Every frame then represents a certain degree as the camera spins around the given axiis. When a large light source such as the moon or the sun pass the camera, this gets recorded and because a revolution is not completed it's able to pinpoint exactly that this is another light source, and then determine the angle.

So what good is knowing the angle of the sun or moon? Once you have measured where the sun is at its highest point in the sky (the peak) you know that it is noon (or high noon) and you also know that the sun must be exactly south in the northern hemisphere and exactly north in the southern hemisphere. This gives you a bearing. You can also use this as a clock now. Mapping the 2 yearly solstices and equinoxes now is not that hard, and it is automated meaning you don't have to attend it all the time. This isn't the only good function. Pretend the camera is infrared, or ultraviolet or other rays that are emitted by our sun not visible to the eye. You can now track the sun behind cloud cover (at least theoretically), this is important for regions that are overcast often (some parts of europe perhaps?). Once you plotted the sun and the moon you should be able to plot your own position to be absolutely sure where on earth you are, without requiring GPS, and doing it in a very reliable manner. If the camera picks up stars, or bright planets as well that's a bonus. I have purchased a few cameras on ebay to see this idea become a reality in time. When this construct is finished I'll give you an update.

PS: You can have GPS, but if GPS fails then your reliance is left to the elements. Similarily a GPS system can be encrypted at will by the USA, or the sun may cause such a solar storm that knocks out the electronics on all or partially all GPS satellites. You can fake electromagnetic sources with electricity, so a compass may not help much. One can pollute the atmosphere with smoke or steam in order to cover up the sun or moon but there will be times when wasting energy on such a level isn't always available. Sun and moon cannot so easily be moved by any invention of mankind, and this solidifies where you are, without reliance and dependance on others. The use of this is extremely important.