Tuesday, March 24, 2009
Great Links!
Thanks for listening.
See you tonight. :)
http://www.windows.ucar.edu/tour/link=/earth/moons_and_rings.html
http://nssdc.gsfc.nasa.gov/planetary/planets/moonpage.html
http://www.nasa.gov/worldbook/moon_worldbook.html
Monday, March 23, 2009
Exploration!
The Cold War-inspired space race between the Soviet Union and the U.S. led to an acceleration of interest in me. Unmanned probes, both flyby and impact/lander missions, were sent almost as soon as launcher capabilities would allow it. The Soviet Union's Luna program was the first to reach me with an unmanned spacecraft.
Eclipses
Lunar eclipses are special events that only occur when certain conditions are met. First of all, Imust be in "full phase". Secondly, I have to be perfectly in a straight line with the Sun and the Earth. If both of these are met, then the Earth's shadow can block the Sun's light from hitting me.
There are three types of my eclipses. Which one we will see depends on the alignment of the three celestial objects. But first, you need to know that the Earth's shadow is broken up into two parts. The umbra is the darker part of the shadow, where no part of the Sun can been seen. The penumbra is lighter than the umbra, because part of the Sun can be seen.
So, when part of mepasses through the umbra, this is called a partial eclipse. When all of me passes through the umbra, this is called a total eclipse. Finally, when I only passes through the penumbra, this is called a penumbral eclipse.
Now that you know all about eclipses, you can step outside and enjoy the show! It is my time to shine! Well, maybe not so much 'shine'... but there are always s many of you looking up at me and it makes me feel special!
Remember that my eclipses are not dangerous to the human eye, so you don't need protection to watch. Just find a nice, cozy spot and enjoy!
Lunar Eclipses: 2000 through 2020-http://www.windows.ucar.edu/tour/link=/moon/lunar_eclipse_stats.html
I control your Ocean Tides!
Keep it Simple!
For those of you that are having a little trouble following all of the big words and how complicated I might be, this post is for you!!
The Earth's one natural satellite, ME, is more than one quarter the size of Earth itself (3,474 km diameter). Because of its smaller size, my gravity is one-sixth of the Earth's gravity!
While there are only two basic types of regions on my surface, there are many interesting surface features such as craters, mountain ranges, and lava plains.
The structure of my interior is more difficult to study. The Moon's top layer is a rocky solid, perhaps 800 km thick. Beneath this layer is a partially molten zone. Although it is not know for sure I may have a small iron core, even though I have no magnetic field.
By studying my surface and interior, geologists can learn about my history an formation.
The footprints left by Apollo astronauts will last for centuries because there is no wind on me!
The Moon does not possess any atmosphere, so there is no weather as we are used to on Earth. Because there is no atmosphere to trap heat, the temperatures here are extreme, ranging from 100° C at noon to -173° C at night!!
I do not produce its own light, but I look bright because I reflect light from the Sun. Think of the beautiful Sun as a light bulb, and me as a mirror, reflecting light from the light bulb. My 'lunar' phase changes as I orbit the Earth and different portions of its surface are illuminated by the Sun.
Hope this helps!
My Origin...?
Early speculation proposed that I broke off from the Earth's crust because of centrifugal forces, leaving a basin – presumed to be the Pacific Ocean – behind as a scar. This idea, however, would require too great an initial spin of the Earth; and, even had this been possible, the process should have resulted in my orbit following Earth's equatorial plane. This is not the case.
Capture hypothesis
Other speculation has centered me being formed elsewhere and subsequently being captured by Earth's gravity. However, the conditions believed necessary for such a mechanism to work, such as an extended atmosphere of the Earth in order to dissipate my energy, are improbable.
Co-formation hypothesis
The co-formation hypothesis proposes that the Earth and meformed together at the same time and place from the primordial accretion disk. I would have formed from material surrounding the proto-Earth, similar to the formation of the planets around the Sun. Some suggest that this hypothesis fails adequately to explain the depletion of metallic iron in me.
A major deficiency in all these hypotheses is that they cannot readily account for the high angular momentum of the 'Earth–Moon' system.
Giant Impact hypothesis
The prevailing hypothesis today is that the my system with the Earth formed as a result of a giant impact. A Mars-sized body (labelled "Theia") is believed to have hit the proto-Earth, blasting sufficient material into orbit around the proto-Earth to form me through accretion. As accretion is the process by which all planetary bodies are believed to have formed, giant impacts are thought to have affected most if not all planets. Computer simulations modelling a giant impact are consistent with measurements of the angular momentum of the 'Earth–Moon' system, as well as the small size of the lunar core.Unresolved questions regarding this theory concern the determination of the relative sizes of the proto-Earth and Theia and of how much material from these two bodies formed me!
Magnetic Field
it's Gravity, Man!
What am I made of?
Cheese?
Nope... sorry!
I am a 'differentiated body' composed of a distinct crust, mantle and core! My structure is believe to have resulted from the fraction crystallization of magma ocean shortly after my formation around 4.4 billion years ago!
My crust, in terms of elements is composed primarily of oxygen, silicon, magnesium, iron, calcium, and aluminum and is estimated to be about 50 km thick.
I have the density of 3346.4 kg/m cubed, making me the second densest moon in the Solar system, after my dear 'moon' friend Io.
My core is small, with a radius of only about 350km or less. This is therefore only 20% of me! As you can see, I am very different from other terrestrial bodies as their composition of core is around 50% of their make up.
Analysis of my time-variable rotation indicate that my core is at least partly molten.
Sunday, March 22, 2009
IMPACT CRATERS!
They say that my surface is marked by impact craters! It sure is! These impact craters form when asteroids and comets collide into me! Ouch*
There are about half a million craters on me with diameters greater than 1 km!
Since impact craters accumulate at a nearly constant rate, the number of craters per unit area superposed on a geologic unit can be used to estimate my age. Because there isn't much of an atmosphere around me, or weather... recent geological processes ensure that many of the craters on me have remained relatively well preserved in comparison to those on Earth.
My largest crater, which is known to be the largest crater in the Solar System, is called the 'South Pole-Aitken basin'. It is on my far side between the South Pole and equator and is 2,240 km in diameter and 13 km in depth!!
Terrae
The lighter-colored regions of my surface are called Terrae, or more commonly just highlands,since they are higher then most of the mare of my surface. Several prominent mountain ranges on the near side are found along the periphery of the giant impact basins, many of which have been filled by mare basalt. These are believed to be the surviving remnants of the impact basin's outer rims In contrast to the Earth, no major lunar mountains are believed to have formed as a result of tectonic events.
From images of my terrae taken by the Clementine mission in 1994, it appears that four mountainous regions on the rim of the 73 km-wide Peary crater at my north pole remain illuminated for the entire lunar day. These peaks of eternal light are possible because of the Moon's extremely small axial tilt to the ecliptic plane. No similar regions of eternal light were found at my south pole, although the rim of Shackleton crater illuminated for about 80% of the lunar day. Another consequence of my small axial tilt is regions that remain in permanent shadow to you on earth, at the bottoms of my polar craters.
Maria, Maria....
she definitely doesn't give me the shine that the Sun does, but she is an important feature of myself that you must know about!
The dark and relatively featureless lunar plans which can clearly be seen with your naked eye are called maria (singular mare), Latin for seas, since they were believe by ancient astronomers to be filled with water! pfft...
These are now know to be vast solidified pools of ancient basaltic lava. The majority of these lavas erupted of flowed with impact basics that formed by the collisions of meteors and comets with the lunar surface, Maria are found almost exclusively on the near side me, with the far side having only a few scattered patches covering about 2% of my surface, compared with about 31% on my near side.
The most likely explanation for this difference is related to a higher concentration of heat-producing elements on the near-side hemisphere, as has been demonstrated by geochemical maps obtained from the Lunar Prospector gamma-ray spectrometer, such a long name!
Several provinces containing shield volcanoes and volcanic domes are found within the near side maria.
This song was NOT created after the maria on my surface....
http://www.youtube.com/watch?v=6Ml3NUIDpFg
Two Side of Me
Okay,
So... I am in 'synchronous rotation', which means that I rotate about my axis in the about same time it takes to orbit the Earth. This results in keeping nearly the same face turned towards you on Earth at all times!
I used to rotate at a faster rate, but early in history, my rotation slowed and became locked in this orientation as a result of frictional effects associated with tidal deformations caused by the Earth.
Small variations in the angle of which you can see me on Earth allow for you to see about 59% of my surface, but only half at any instant.
It was the Russians who were the first to take photographs of my 'far side' through the Soviet Space Program, Luna 3 in 1958.
Link:
"The Unseen Side of the Moon":
http://www.youtube.com/watch?v=GTmovPeu3GM
The side of me that faces the Earth is called the "near side", and the opposite side, is called the "far side". The far side of me is often inaccurately called the "dark side" just like Pink Floyds' 1973 concept album "The Dark Side of the Moon"- http://www.youtube.com/watch?v=d78K4rCEfAo&feature=related, but in fact it is illuminated exactly as often as the near side: once, per lunar day.
A distinguishing feature of my "far side" is that its almost complete lack of maria.
Welcome
So let me begin,
I am The Moon (Latin: Luna).
I am the Earth's only natural satellite and the fifth largest satellite in the Solar System. I live about 384,403 km away from you, on Earth! I make a complete orbit around the Earth every 27.3 days, this is called my "orbital period". The periodic variations in the geometry of the Earth–Moon– and the Sun system are responsible for the 'lunar phases' that repeat every 29.5 days.I am much smaller then your planet, Earth. I am about a quarter of the Earth's diameter which is 3,474 kms. Therefore my surface area is less then 1/10th of the Earth!
I am the only celestial body to which humans, like you have traveled and upon which humans have performed a manned landing. The first artificial object to pass near me was the 'Soviet Union's Luna 1, the first artificial object to impact my surface was Luna 2 and the first photographs of the "far side of me" ("the far side of the Moon") were made by Luna 3 all in 1959!
The first space craft to perform a successful landing on my was Luna 9, and the first unmanned vehicle to orbit the Moon was Luna 10, both in 1966!
The Unite States Apollo program achieved the only manned mission to date, resulting in six landings and visit to me between 1969 and 1972
Human explorate of me ceased with the conclusion of the Apollo program, although a few robotic landers and orbiters have been sent to visit me since then. I liked it more when humans visited me!
I have heard talk that several countries have announced plans to return humans to the surface of the Moon in the 2020's. I can't wait!