“One small step for man, one giant leap for mankind” – this is what Neil Armstrong, an American and the first man to step on the surface of the Moon, had to say. Truly, the first steps of mankind on the Moon have been immortalized, literally and figuratively (since there’s no atmosphere on the Moon, the footprints of all the astronauts will be preserved for millions of years due to absence of erosion). This little satellite of our planet has been very popular among artists and scientists alike. Humans have found out a lot of information about the Moon and we are still sending unmanned voyages to the Moon to find out more – the latest being the ‘Chandrayaan’ by India.

Moon Formation

The Moon is estimated to have come into formation about 30-50 million years after the Solar System came into being. That makes the Moon more than 4.527 billion years old – the Earth itself is 4.54 billion years old. Some researchers and computer simulations suggest that in the initial days of the Earth, its spin was so great that the immense centrifugal force caused the fission of the Moon from the Earth’s crust. However, in order for the Earth to gravitionally capture the pre-formed Moon, its atmosphere would have had to be unfeasably extended from what exists today.

Another hypothesis takes into consideration the fact that in the early days of the Solar System, giant impacts between planets and huge asteroids or meteorites were very common, and this theory suggests that a similar giant impact was responsible for the formation of the Moon. Possibilities exists that a Mars-sized planet collided with the newly formed Earth, thus blasting material from the Earth into the orbit resulting in the formation of the Earth-Moon system.

Moon Atmosphere and Temperatures

It would be incorrect to say that the Moon has no atmosphere at all, though it is so insignificant that it is easier to ignore its presence. Total weight of the Moon’s atmosphere is about 10 metric tons; compare that with the Earth’s atmpsphere which is about 5 quadrillion tons. This causes the temperature ranges to be at extremes on the Moon and the Sun is the only factor which influences it. The temperature on the side of the Moon facing the Sun can go upto a maximum of 123°C (253°F) while the side in darkness can record temperatures as low as -153°C (-243°F). The poles and the perpetually dark craters can sometimes experience temperatures close to the absolute zero.

Moon Size and Speed

The Earth’s Moon is the second largest moon of the Solar Syste, when the relative size is taken into consideration. In other words, the relative size of the Earth and the Moon is quite large when compared to the relative sizes of planets like Jupiter and Saturn and their moons. The diameter of the Moon is 2,000 miles ( 3,476 kilometres). To give an idea of the surface area of the Moon, it is comparable to the size of the continent of Africa. The speed at which the Moon orbits the Earth differs according to its distance from the Earth at different points in its orbit. On an average, the Moon revolves around the Earth at 2,288 miles per hour (3,683 kilometres per hour).

Moon Distance to Earth and Lunar Month

The center of the Moon is at a distance of 250,000 miles (384,400 kilometres) from the center of the Earth. A beam of light from the surface of the Earth to the surface of the Moon would take about 1.26 seconds to travel this distance. The Moon takes 27 days, 7 hours, 43 minutes, 11.6 seconds to complete one orbit around the Earth. It should be noted that the Lunar month (time between two new moons) is considered to be 29 days, 12 hours, 43 minutes, 11.6 seconds long. Though the two are basically based on the same phenomenon – i.e. the completion of one orbit around the Earth – the difference in time arises since the Earth is constantly moving around the Sun and thus the Moon has to cover more than 360 degrees to complete one revolution around the Earth.

The Moon has quite a few influences on the Earth and a lot of changes would affect the Earth if the Moon was to be taken out of the picture. For example, the gravitational pull of the Moon causes the water of the oceans to move away from the polar regions. Without the Moon, the water would redistribute itself near the polar regions and cause the sea levels to change a little. The spin of the Earth is slowed down by the Moon and without the Moon we would experience shorter days. Also, the axis of rotation of the Earth is said to be stabilized due to the Moon.

Though only two countries have so far reached the Moon, an international treaty has been signed which declares the Moon as a property of the whole of mankind. This restricts countries from using the Moon for anything other than peaceful purposes.

Related Articles about Solar System Moons

[images: nasa.gov]

The first planet in the habitable zone around a Sun-like star was discovered by the Kepler telescope. The new object was named Kepler 22-b. It revolves around a star, which is located at a distance of 600 light years away from Earth. The star belongs to the G spectral class (which is the same spectral class as our Sun), but it is slightly smaller and cooler than the Sun – the brightness of the star is about ¾ of our Sun’s.

Kepler 22-b revolves around its star in 290 days. The radius of the planet is about 2.4 times larger than the Earth. Scientists do not know the mass of the planet, so it is not possible to estimate its density and hence the approximate composition. It is quite possible that the planet may consist almost entirely of gas.

The planet is also known as Christmas Planet. It got it’s nickname because it took three snapshots for the Kepler telescope to determine the planet was really there, and the snapshots had to be taken 290 days apart (the length of planet’s year). The last of those three encounters happened during the 2010 holiday season.

According to the scientists, to date, Kepler telescope has found 54 candidates for a potentially habitable planet.  Habitable zone around a star is a region where the planet’s surface (if it exists) can potentially have liquid water.

Space telescope Kepler was launched into space in March 2009. It continuously scans the area in the sky, containing about 4.5 million stars, which is located between Cygnus and Lyra constellations. Scientists find extrasolar planets by monitoring changes in star brightness caused by the passage of a body across the disk of a star (so-called transit method).

[images - nasa.gov]

Few days ago we all witnessed the last space shuttle launch. The 30 years of shuttle history, starting with Columbia’s first flight in 1981 was a remarkable tale of achievement… and tragedy.

Based on an idea mooted by NASA’s German-born early space pioneer Wernher von Braun, the shuttle was a brilliant concept: a low-earth orbit, reusable spacecraft that could carry seven astronauts and almost 23,000 kg of cargo in its hold.

The shuttle’s ingenuity was its ability to dock with a space station orbiting Earth, deliver and retrieve goods, deploy satellites, carry out repairs, conduct experiments and return to Earth for repeated use by landing like a jet airliner.

The shuttle has performed these operations and returned safely 132 times by always had its limitations: as a low-orbit spacecraft it could never venture far from Earth. It was essentially a workhorse, not a vehicle for pursuing NASA’s broader objective of exploring deep space.

Cost was also an issue. The bill for each shuttle trip has remained close to $US1.5 billion despite early dreams of a drastically deduced sum once launches became a regular event.

NASA also faced dealing with an ageing fleet: Atlantis, the last shuttle in operation for last week’s final 135th launch, was commissioned in 1985. At some point, if the program had continued, NASA would have needed a fleet overhaul. The shuttle’s most nagging problem, however, had been a design flaw that contributed directly to the loss of two spacecraft and deaths of 14 astronauts.

In 1986, when a flame leak from the solid rocket booster ignited the external fuel tank, the shuttle Challenger exploded 73 seconds after lift-off, killing all seven crew on board.

And Columbia disintegrated during re-entry in 2003, also killing its crew of seven, after a mishap went undetected during lift-off: a chunk of foam insulation broke away from the external fuel tank and damaged a heat-shield tile on the shuttle’s wing.

These malfunctions were linked to having the shuttle attached to the sides of the external fuel tank, and two rocket boosters at launch time. The shuttle’s configuration – different to the old Apollo capsules – effectively guaranteed that if the fuel tank and rocket boosters experienced anomalies, the piloted shuttle was in immediate harm’s way.

The Columbia disaster forced a temporary shutdown of the program and ultimately its demise. President George W. Bush endorsed a replacement program in 2004 called Constellation that sought to gradually phase out the three surviving shuttles and redirect NASA funds into new missions: a resumption of moon landing and the first manned flight to Mars.
 

When Obama took over as President in 2009, the constellation program was behind schedule because of under-funding by Congress and technical difficulties associated with developing Ares 1, a proposed powerful new rocket. Obama’s solution, after a review uncovered a huge funding shortfall, was to cancel Constellation last year.

He kept the program’s long-term goal of deep space exploration using heavy lift rocket boosters but dumped moon landings. While short on detail, Obama says he expect manned missions to nearby asteroids by mid-2020’s and flights to orbit Mars by the mid-2030’s. “A landing on Mars will follow, and I expect to be around to see it,” he says.

[images - www.nasa.gov]

Related Earth Articles

Related Articles About Space Missions

Earth’s surface is the outermost layer of the planet. It includes the hydrosphere, the crust, and the biosphere.

Hydrosphere

The hydrosphere consists of the bodies of water that cover 71 percent of Earth’s surface. The largest of these are the oceans, which contain over 97 percent of all water on Earth. Glaciers and the polar ice caps contain just over 2 percent of Earth’s water in the form of solid ice. Only about 0.6 percent is under the surface as groundwater. Nevertheless, groundwater is 36 times more plentiful than water found in lakes, inland seas, rivers, and in the atmosphere as water vapor. Only 0.017 percent of all the water on Earth is found in lakes and rivers. And a mere 0.001 percent is found in the atmosphere as water vapor. Most of the water in glaciers, lakes, inland seas, rivers, and groundwater is fresh and can be used for drinking and agriculture. Dissolved salts compose about 3.5 percent of the water in the oceans, however, making it unsuitable for drinking or agriculture unless it is treated to remove the salts.

Crust

The crust consists of the continents, other land areas, and the basins, or floors, of the oceans. The dry land of Earth’s surface is called the continental crust. It is about 15 to 75 km (9 to 47 mi) thick. The oceanic crust is thinner than the continental crust. Its average thickness is 5 to 10 km (3 to 6 mi). The crust has a definite boundary called the Mohorovi.

Oceanic crust and continental crust differ in the type of rocks they contain. There are three main types of rocks: igneous, sedimentary, and metamorphic. Igneous rocks form when molten rock, called magma, cools and solidifies. Sedimentary rocks are usually created by the breakdown of igneous rocks. They tend to form in layers as small particles of other rocks or as the mineralized remains of dead animals and plants that have fused together over time. The remains of dead animals and plants occasionally become mineralized in sedimentary rock and are recognizable as fossils. Metamorphic rocks form when sedimentary or igneous rocks are altered by heat and pressure deep underground.

Oceanic crust consists of dark, dense igneous rocks, such as basalt and gabbro. Continental crust consists of lighter-colored, less dense igneous rocks, such as granite and diorite. Continental crust also includes metamorphic rocks and sedimentary rocks.

Biosphere

The biosphere includes all the areas of Earth capable of supporting life. The biosphere ranges from about 10 km (about 6 mi) into the atmosphere to the deepest ocean floor. For a long time, scientists believed that all life depended on energy from the Sun and consequently could only exist where sunlight penetrated. In the 1970s, however, scientists discovered various forms of life around hydrothermal vents on the floor of the Pacific Ocean where no sunlight penetrated. They learned that primitive bacteria formed the basis of this living community and that the bacteria derived their energy from a process called chemosynthesis that did not depend on sunlight. Some scientists believe that the biosphere may extend relatively deep into Earth’s crust. They have recovered what they believe are primitive bacteria from deeply drilled holes below the surface.

Changes to Earth’s Surface

Earth’s surface has been constantly changing ever since the planet formed. Most of these changes have been gradual, taking place over millions of years. Nevertheless, these gradual changes have resulted in radical modifications, involving the formation, erosion, and re-formation of mountain ranges, the movement of continents, the creation of huge supercontinents, and the breakup of supercontinents into smaller continents.

The weathering and erosion that result from the water cycle are among the principal factors responsible for changes to Earth’s surface. Another principal factor is the movement of Earth’s continents and seafloors and the buildup of mountain ranges due to a phenomenon known as plate tectonics. Heat is the basis for all of these changes. Heat in Earth’s interior is believed to be responsible for continental movement, mountain building, and the creation of new seafloor in ocean basins. Heat from the Sun is responsible for the evaporation of ocean water and the resulting precipitation that causes weathering and erosion. In effect, heat in Earth’s interior helps build up Earth’s surface while heat from the Sun helps wear down the surface.

Weathering

Weathering is the breakdown of rock at and near the surface of Earth. Most rocks originally formed in a hot, high-pressure environment below the surface where there was little exposure to water. Once the rocks reached Earth’s surface, however, they were subjected to temperature changes and exposed to water. When rocks are subjected to these kinds of surface conditions, the minerals they contain tend to change. These changes constitute the process of weathering. There are two types of weathering: physical weathering and chemical weathering.

Physical weathering involves a decrease in the size of rock material. Freezing and thawing of water in rock cavities, for example, splits rock into small pieces because water expands when it freezes.

Chemical weathering involves a chemical change in the composition of rock. For example, feldspar, a common mineral in granite and other rocks, reacts with water to form clay minerals, resulting in a new substance with totally different properties than the parent feldspar. Chemical weathering is of significance to humans because it creates the clay minerals that are important components of soil, the basis of agriculture. Chemical weathering also causes the release of dissolved forms of sodium, calcium, potassium, magnesium, and other chemical elements into surface water and groundwater. These elements are carried by surface water and groundwater to the sea and are the sources of dissolved salts in the sea.

Erosion

Glacial Erosion Glaciers erode the earth’s surface through processes such as abrasion, crushing, and fracturing of the material in the glacier’s path. Glaciers move by growing or shrinking, depending on the climate. Moving glaciers erode and transport large quantities of rocks, sand, and other particles along their path. The icy path shown here is a moraine formed by a glacier in Switzerland.

Erosion is the process that removes loose and weathered rock and carries it to a new site. Water, wind, and glacial ice combined with the force of gravity can cause erosion.

Erosion by running water is by far the most common process of erosion. It takes place over a longer period of time than other forms of erosion. When water from rain or melted snow moves downhill, it can carry loose rock or soil with it. Erosion by running water forms the familiar gullies and V-shaped valleys that cut into most landscapes. The force of the running water removes loose particles formed by weathering. In the process, gullies and valleys are lengthened, widened, and deepened. Often, water overflows the banks of the gullies or river channels, resulting in floods. Each new flood carries more material away to increase the size of the valley. Meanwhile, weathering loosens more and more material so the process continues.

Erosion by glacial ice is less common, but it can cause the greatest landscape changes in the shortest amount of time. Glacial ice forms in a region where snow fails to melt in the spring and summer and instead builds up as ice. For major glaciers to form, this lack of snowmelt has to occur for a number of years in areas with high precipitation. As ice accumulates and thickens, it flows as a solid mass. As it flows, it has a tremendous capacity to erode soil and even solid rock. Ice is a major factor in shaping some landscapes, especially mountainous regions. Glacial ice provides much of the spectacular scenery in these regions.

Wind is an important cause of erosion only in arid (dry) regions. Wind carries sand and dust, which can scour even solid rock.

Many factors determine the rate and kind of erosion that occurs in a given area. The climate of an area determines the distribution, amount, and kind of precipitation that the area receives and thus the type and rate of weathering. An area with an arid climate erodes differently than an area with a humid climate. The elevation of an area also plays a role by determining the potential energy of running water. The higher the elevation the more energetically water will flow due to the force of gravity. The type of bedrock in an area (sandstone, granite, or shale) can determine the shapes of valleys and slopes, and the depth of streams.

A landscape’s geologic age—that is, how long current conditions of weathering and erosion have affected the area—determines its overall appearance. Relatively young landscapes tend to be more rugged and angular in appearance. Older landscapes tend to have more rounded slopes and hills. The oldest landscapes tend to be low-lying with broad, open river valleys and low, rounded hills. The overall effect of the wearing down of an area is to level the land; the tendency is toward the reduction of all land surfaces to sea level.

Plate Tectonics

Opposing this tendency toward leveling is a force responsible for raising mountains and plateaus and for creating new landmasses. These changes to Earth’s surface occur in the outermost solid portion of Earth, known as the lithosphere. The lithosphere consists of the crust and another region known as the upper mantle and is approximately 65 to 100 km (40 to 60 mi) thick. Compared with the interior of the Earth, however, this region is relatively thin. The lithosphere is thinner in proportion to the whole Earth than the skin of an apple is to the whole apple.

Scientists believe that the lithosphere is broken into a series of plates, or segments. According to the theory of plate tectonics, these plates move around on Earth’s surface over long periods of time. Tectonics comes from the Greek word, tektonikos, which means “builder.”

According to the theory, the lithosphere is divided into large and small plates. The largest plates include the Pacific plate, the North American plate, the Eurasian plate, the Antarctic plate, the Indo-Australian plate, and the African plate. Smaller plates include the Cocos plate, the Nazca plate, the Philippine plate, and the Caribbean plate. Plate sizes vary a great deal. The Cocos plate is 2,000 km (1,000 mi) wide, while the Pacific plate is nearly 14,000 km (nearly 9,000 mi) wide.

These plates move in three different ways in relation to each other. They pull apart or move away from each other, they collide or move against each other, or they slide past each other as they move sideways. The movement of these plates helps explain many geological events, such as earthquakes and volcanic eruptions as well as mountain building and the formation of the oceans and continents.

Related Earth Articles
Related Articles about Solar System Planets