PEPPERIDGE FARM – THE SNACK THAT SMILES BACK…GOLDFISH:)

Adventures to the moon Meghan McDaniel’s daily reader

Special thanks to Rheagan Titsworth

3/5/2012

40 years ago, three human beings - with the help of many thousands of others - left our planet on a successful journey to our Moon, setting foot on another world for the first time. Apollo 11 was launched on July 16, 1969 with Engineer Neil A. Armstrong, command module pilot Michael Collins and Engineer Edwin E. "Buzz" Aldrin Jr. aboard. Armstrong and Aldrin walked on the Moon. The entire trip for the Astronauts lasted only 8 days, the time spent on the surface was less than one day, the entire time spent walking on the moon, a mere 2 1/2 hours - but they were surely historic hours. Scientific experiments were deployed (at least one still in use today), samples were collected, and photographs were taken to document the entire journey. Collected here are 40 images from that journey four decades ago, when, in the words of astronaut Buzz Aldrin: "In this one moment, the world came together in peace for all

mankind".

New Moon Waxing Crescent 1st Quarter

Waxing Gibbous Full Moon Waning Gibbous

3rd Quarter Waning Crescent

, then it starts all over.

Composition of the moon

Elements known to be present on the lunar surface include, among others, oxygen (O), silicon

(Si), iron (Fe), magnesium (Mg), calcium (Ca), aluminium (Al), manganese (Mn) and titanium

(Ti). Among the more abundant are oxygen, iron and silicon. The oxygen content is estimated at

45%. Carbon (C) and nitrogen (N) appear to be present only in trace quantities from deposition

by solar wind.

Neutron spectrometry data from the Lunar Prospector indicate the presence of hydrogen (H)

concentrated at the poles.[1]

Theories of how the moon was formed

Lunar capture

This hypothesis states that the Moon was captured, completely formed, by the gravitational field

of the Earth. This is unlikely, since a close encounter with the Earth would have produced either

a collision or an alteration of the trajectory of the body in question, so if it had indeed happened,

the Moon probably would never return to meet again with the Earth. For this hypothesis to

function, there would have to be a large atmosphere extended around the primitive Earth, which

would be able to slow the movement of the Moon before it could escape. This hypothesis is

considered to explain the irregular satellite orbits of Jupiter and Saturn.[3]

In addition, this

hypothesis has difficulty explaining the essentially identical oxygen isotope ratios of the two

worlds.[4]

[edit] Co-accretion hypothesis

This hypothesis states that the Earth and the Moon formed together as a double system from the

primordial accretion disk of the Solar System.[citation needed]

The problem with this hypothesis is

that it does not explain the angular momentum of the Earth-Moon system, nor why the Moon has

a relatively small iron core compared to the Earth (25% of its radius compared to 50% for the

Earth).[citation needed]

[edit] Giant impact theory

Main article: Giant impact theory

At present the most widely accepted explanation for the origin of the Moon involves a collision

of two protoplanetary bodies during the early accretional period of Solar System evolution. This

"giant impact theory", which became popular in 1984 (although Reginald Aldworth Daly, a

Canadian professor at Harvard college, originated it in the 1940s), satisfies the orbital conditions

of the Earth and Moon and can account for the relatively small metallic core of the Moon.

Collisions between planetesimals are now recognized to lead to the growth of planetary bodies

early in the evolution of the Solar System, and in this framework it is inevitable that large

impacts will sometimes occur when the planets are nearly formed.

The theory requires a collision between a body about 90% the present size of the Earth, and

another the diameter of Mars (half of the terrestrial radius and a tenth of its mass). The colliding

body has sometimes been referred to as Theia, the mother of Selene, the Moon goddess in Greek

mythology. This size ratio is needed in order for the resulting system to possess sufficient

angular momentum to match the current orbital configuration. Such an impact would have put

enough material into orbit about the Earth to have eventually accumulated to form the Moon.

Computer simulations of this event appear to show that the collision must occur with a somewhat

glancing blow. This will cause a small portion of the colliding body to form a long arm of

material that will then shear off. The asymmetrical shape of the Earth following the collision

then causes this material to settle into an orbit around the main mass. The energy involved in this

collision is impressive: trillions of tons of material would have been vaporized and melted. In

parts of the Earth the temperature would have risen to 10,000°C (18,000°F).

This formation theory helps explain why the Moon possesses only a small iron core (roughly

25% of its radius, in comparison to about 50% for the Earth). Most of the iron core from the

impacting body is predicted to have accreted to the core of the Earth. The lack of volatiles in the

lunar samples is also explained in part by the energy of the collision. The energy liberated during

the reaccreation of material in orbit about the Earth would have been sufficient to melt a large

portion of the Moon, leading to the generation of a magma ocean.

The newly formed moon orbited at about one-tenth the distance that it does today, and became

tidally-locked with the Earth, where one side continually faces toward the Earth. The geology of

the Moon has since been independent of the Earth. While this theory explains many aspects of

the Earth-Moon system, there are still a few unresolved problems facing this theory, such as the

Moon's volatile elements not being as depleted as expected from such an energetic impact.[5]

The moon’s size and distance from Earth

The diameter of the Moon is only 3,474 km across. Just for comparison, the diameter of the

Earth at the equator is 12,756 km. That’s only 27% the diameter of the Earth. The Moon is also

the 5th largest moon in the Solar System, after Ganymede, Titan, Callisto and Io.

In terms of volume, the Moon only contains 2.195 x 1010

km3. That sounds like a lot of cubic

kilometers of Moon, but again, that’s only 2% the volume of Earth.

The surface area of the Moon is 3.793 x 107 km

2. That’s about the same size as Russia, Canada

and the United States combined.

The circumference of the Moon is 10,921 km. Again, that’s only a little over a quarter the

circumference of the Earth.

The average distance between the Moon and the Earth is 384,403 kilometers (238,857 miles).

The moon's orbit is not a perfect circle, it is an ellipse; So the distance isn't constant ... there is a

minimum and a maximum. The distance fluctuates between 363,104 kilometers and 405,696 kilometers

(225,622 to 252,088 miles) due to the eccentricity of the Moon's orbit.

The Orbit of the moon

The Moon completes its orbit around the Earth in approximately 27.3 days (a sidereal month).

The Earth and Moon orbit about their barycentre (common centre of mass), which lies about

4700 km from Earth's centre (about three quarters of the Earth's radius). On average, the Moon is

at a distance of about 385000 km from the centre of the Earth, which corresponds to about 60

Earth radii. With a mean orbital velocity of 1,023 m/s[1]

, the Moon moves relative to the stars

each hour by an amount roughly equal to its angular diameter, or by about 0.5°. The Moon

differs from most satellites of other planets in that its orbit is close to the plane of the ecliptic,

and not to the Earth's equatorial plane. The lunar orbit plane is inclined to the ecliptic by about

5.1°, whereas the Moon's spin axis is inclined by only 1.5°.

The effects the moon has on the Earth

The gravitational attraction that the Moon exerts on Earth is the cause of tides in the sea. The tidal flow

period is synchronized to the Moon's orbit around Earth, but the phase isn't. The tidal bulges on Earth,

caused by the Moon's gravity, are carried ahead of the apparent position of the Moon by the Earth's

rotation, in part because of the friction of the water as it slides over the ocean bottom and into or out of

bays and estuaries. As a result, some of the Earth's rotational momentum is gradually being transferred

to the Moon's orbital momentum, resulting in the Moon slowly receding from Earth at the rate of

approximately 38 mm per year. At the same time the Earth's rotation is gradually slowing, the Earth's

day thus lengthens by about 15 µs every year.

Missions to the moon timeline