Little Bits of History


Posted in History by patriciahysell on November 30, 2015
The Earth-Moon system

The Earth-Moon system

November 30, 3340 BC: An eclipse is recorded. At least that is a theory proposed by Paul Griffin who argues a stone in Ireland records the event. Records of solar eclipses have been kept since ancient times as the event was seen as a propitious omen. A Syrian clay tablet records the event in the Ugaritic language and tells of a solar eclipse which took place on March 5, 1223 BC (using the Gregorian calendar). The Babylonians also recorded the events and their records from the 13th century BC may have been used to help the Greeks find all three lunar motions to an extremely precise degree. They were able to calculate synodic, anomalistic, and draconitic motions to about one part in a million. The Chinese have been recording solar eclipses for about 4,000 years and these have been used to calculate the changes in the Earth’s rate of spin.

An eclipse is an astronomical event which takes place when one object is temporarily obscured by the passing of another body or by the passing of the shadow of another body across it. The word eclipse comes from the Greek ékleipsis which means “the abandonment”, “the downfall”, or “the darkening of a heavenly body”. This gives a rather ominous flavor to the word. There are different types of eclipses, but the term when left to stand alone usually refers to a solar eclipse which happens with the Moon passes between the Earth and the Sun. This only works when there is a new moon and when the Sun and the Moon are in conjunction as seen from Earth. Since orbits are not completely in alignment, this is not a monthly occurrence.

A lunar eclipse takes place when the Moon passes behind the Earth and is covered by the shadow it casts. Again, all three entities, Sun, Moon, and Earth, have to be perfectly aligned for this to happen, something called syzygy. A lunar eclipse can only take place on the night of a full moon. Other differences between the two types of eclipses is that a lunar eclipse lasts for hours rather than the few minutes a solar eclipse lasts. And a lunar eclipse can be seen from anywhere on the night side of Earth. A total solar eclipse can only been seen on a small portion of the planet. It is safe for anyone to gaze up into the night sky to witness a lunar eclipse and they will not damage their eyes. However, eye protection is needed if one is to look directly at a solar eclipse.

There are three parts of the Moon’s shadow in a solar eclipse. The umbra is the part where the Moon completely covers the sun. Because of the sizes of the bodies involved, it is possible, at times, for the Moon to seem to completely block the sun. The umbra moves eastward at a rate of 1050 mph and is seen along a track 155 miles wide. It can last up to 7 minutes and 31 seconds under the most favorable circumstances, that is when everything is perfectly aligned. It is interesting to note that astronauts in space can witness an eclipse unlike anything we can see on Earth. They have witnessed an eclipse of the Earth over the Sun. The Cassini probe was able to see Saturn eclipse the Sun in 2006.

There is no science in this world like physics. Nothing comes close to the precision with which physics enables you to understand the world around you. It’s the laws of physics that allow us to say exactly what time the sun is going to rise. What time the eclipse is going to begin. What time the eclipse is going to end. – Neil deGrasse Tyson

All Science is necessarily prophetic, so truly so, that the power of prophecy is the test, the infallible criterion, by which any presumed Science is ascertained to be actually & verily science. The Ptolemaic Astronomy was barely able to prognosticate a lunar eclipse; with Kepler and Newton came Science and Prophecy. – Samuel Taylor Coleridge

I have always read that the world, both land and water, was spherical, as the authority and researches of Ptolemy and all the others who have written on this subject demonstrate and prove, as do the eclipses of the moon and other experiments that are made from east to west, and the elevation of the North Star from north to south. – Christopher Columbus

The earth together with its surrounding waters must in fact have such a shape as its shadow reveals, for it eclipses the moon with the arc of a perfect circle. – Copernicus

Also on this day: I’ll Take Television for $200, Alex – In 2004, Ken Jennings finally lost at Jeopardy! after winning over $2.5 million.
100 Miles Per Hour – In 1934, the Flying Scotsman reached a speed of 100 mph.
Lucy – In 1974, Australopithecus was discovered.
Penal Reform – In 1786, the death penalty was outlawed for the first time.
Crystal Palace – In 1936, the palace burned to the ground.

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