Moon Apogee & Perigee.

The point of closest approach (the point at which two bodies are the closest) is called the periapsis or pericentre, from Greek, peri, around, and κέντρον. The point of farthest excursion is called the apoapsis apó, from, apocentre or apapsis  before an unaspirated, or ἀφ-, aph-, before an aspirated vowel, respectively]), (the latter term, although etymologically more correct, is much less used). A straight line drawn through the periapsis and apoapsis is the line of apsides. This is the major axis of the ellipse, the line through the longest part of the ellipse.

Derivative terms are used to identify the body being orbited. The most common are perigee and apogee, referring to orbits around the Earth (Greek γῆ, gê, "earth"), and perihelion and aphelion, referring to orbits around the Sun (Greek ἥλιος, hēlios, "sun"). During the Apollo program, the terms pericynthion and apocynthion were used when referring to the moon.

The apoapsis of an orbit of one object around another is the point at which the one object is furthest away from the other object. Apoapsis is the general term for such a point, but there are also many specific terms for specific cases: the aphelion is the furthest point from the Sun in an orbit around the Sun. Likewise, apoastron is linked to other stars, apogee to the Earth, and apojove to Jupiter. The opposite is periapsis. The word apofocus is sometimes used instead of apoapsis, and apse instead of apsis.

The periapsis of an orbit of one object around another is the point at which the one object is closest to the other object. Periapsis is the general term for such a point, but there are also many specific terms for specific cases: the perihelion is the closest point to the Sun in an orbit around the Sun. Likewise, periastron is linked to other stars, perigeum to the Earth, and perijove to Jupiter.

                                     

                                                

A common misconception is that the sun is larger when it is near the horizon than when it is high overhead. However, this optical illusion is not true, for the apparent size of the sun is virtually the same when it is rising or setting near the horizon or when viewed overhead (in fact, it is very slightly smaller when viewed near the horizon due to refraction as well as the greater added distance in observing across the earth's radius). This illusion has been wrongly attributed to landmarks near the horizon, such as homes and trees, supposedly giving a sense of perspective and whereas the same perspective is lost when looking at the overhead sun bathed in an empty sky.

However, if we were approach the apparent size of the sun methodically by studying it during perihelion and aphelion, we can detect a small change using photographic equipment thanks to the elliptical orbit of our planet around the sun which leads to variations in distance (and apparent size) of the order of about 3.4%. More specifically, at perihelion each January, earth is approximately 147 million km away from the sun and whose apparent diameter is about 32.53' whereas, at aphelion each July, earth is approximately 152 million km away and the sun is characterized with an apparent diameter of about 31.46'. This difference of 5 million km between perihelion and aphelion leads to the slight change in the apparent diameter of the sun as illustrated by the two images of the sun below captured six months apart when the sun was near its minimum possible perihelion (Jan 2/2005) and maximum possible aphelion (Jul 5/2005) and while crossing the local meridian.

2011 Japan Earthquake and Tsunami

The 2011 Japan earthquake and tsunami which shattered the Northeast region Pacific Ocean offshore earthquake was a 9.0-magnitude undersea megathrust earthquake off the coast of Japan that occurred at 14:46 JST (05:46 UTC) on Friday 11 March 2011. The epicenter was approximately 72 kilometers (45 mi) east of the Oshika Peninsula of Japan, with the hypocenter at an underwater depth of approximately 32 km (19.9 mi).

Map of the Japan earthquake and aftershock

The earthquake triggered extremely destructive tsunami waves of up to 10 meters (33 ft) that struck Japan minutes after the quake, in some cases traveling up to 10 km (6 mi) inland,[9] with smaller waves reaching many other countries after several hours. Tsunami warnings were issued and evacuations ordered along Japan's Pacific coast and at least 20 other countries, including the entire Pacific coast of North America and South America.

The Japanese National Police Agency has officially confirmed 9,811 deaths, 2,779 injured, and 17,541 people missing across eighteen prefectures, as well as over 125,000 buildings damaged or destroyed. The earthquake and tsunami caused extensive and severe structural damage in Japan, including heavy damage to roads and railways as well as fires in many areas, and a dam collapse. Around 4.4 million households in northeastern Japan were left without electricity and 1.5 million without water. Many electrical generators were taken down, and at least three nuclear reactors suffered explosions due to hydrogen gas that had built up within their outer containment buildings. On 18 March, Yukiya Amano—the head of the International Atomic Energy Agency—described the crisis as "extremely serious. Residents within a 20 km (12 mi) radius of the Fukushima I Nuclear Power Plant and a 10 km (6 mi) radius of the Fukushima II Nuclear Power Plant were evacuated.                                                     

Estimates of the Japan earthquake's magnitude make it the most powerful known earthquake to have hit Japan, and one of the five most powerful earthquakes in the world overall since modern record-keeping began in 1900. Japanese Prime Minister Naoto Kan said, "In the 65 years after the end of World War II, this is the toughest and the most difficult crisis for Japan." The earthquake moved Honshu 2.4 m (7.9 ft) east and shifted the Earth on its axis by almost 10 cm (3.9 in). Early estimates placed insured losses from the earthquake alone at US$14.5 to $34.6 billion. The Bank of Japan offered ¥15 trillion (US$183 billion) to the banking system on 14 March in an effort to normalize market conditions. On 21 March, the World Bank estimated damage between US$189 billion and $309 billion. Japan's government said the cost of the earthquake and tsunami that devastated the northeast could reach $309 billion, making it the world's most expensive natural disaster on record.

Tsunami hits the Sendai Bay area

2004 Indian Ocean earthquake and tsunami

The 2004 Indian Ocean earthquake was an undersea megathrust earthquake that occurred at 00:58:53 UTC on Sunday, December 26, 2004, with an epicentre off the west coast of Sumatra, Indonesia. The quake itself is known by the scientific community as the Sumatra-Andaman earthquake. The resulting tsunami is given various names, including the 2004 Indian Ocean tsunami, South Asian Tsunami, Indonesian Tsunami, and Boxing Day Tsunami.

The earthquake was caused by subduction and triggered a series of devastating tsunamis along the coasts of most landmasses bordering the Indian Ocean, killing over 230,000 people in fourteen countries, and inundating coastal communities with waves up to 30 meters (100 feet) high. It was one of the deadliest natural disasters in recorded history. Indonesia was the hardest hit, followed by Sri Lanka, India, and Thailand.

With a magnitude of between 9.1 and 9.3, it is the third largest earthquake ever recorded on a seismograph. This earthquake had the longest duration of faulting ever observed, between 8.3 and 10 minutes. It caused the entire planet to vibrate as much as 1 cm (0.4 inches) and triggered other earthquakes as far away as Alaska. Its hypocenter was between Simeulue and mainland Indonesia.

The plight of the many affected people and countries prompted a worldwide humanitarian response. In all, the worldwide community donated more than $14 billion (2004 U.S. dollars) in humanitarian aid.

Tsunami

What is Tsunami

A tsunami is a giant wave (or series of waves) created by an undersea earthquake, volcanic eruption or landslide. Tsunamis are often called tidal waves, but this is not an accurate description because tides have little effect on giant tsunami waves. Far out in the ocean, tsunami waves don’t get very high, but they move very fast. In fact, the National Oceanic and Atmospheric Administration (NOAA) reports that tsunami waves can travel as fast as a jet plane.

As a tsunami gets closer to land and the ocean depth decreases, the speed of the tsunami wave slows down and the height of the tsunami wave increases dramatically—along with its potential for destruction. One thing is certain about tsunamis: they are unpredictable. Once a tsunami makes landfall, the waves can last from five to 15 minutes and do not follow a set pattern. NOAA warns that the first wave may not be the largest, not all undersea earthquakes or other seismic events create tsunamis, which is why tsunamis are difficult to predict.

Earthquakes, volcanic eruptions and other underwater explosions (including detonations of underwater nuclear devices), landslides and other mass movements, meteorite ocean impacts or similar impact events, and other disturbances above or below water all have the potential to generate a tsunami.

The Greek historian Thucydides was the first to relate tsunami to submarine earthquakes, but the understanding of a tsunami's nature remained slim until the 20th century and is the subject of ongoing research. Many early geological, geographical, and oceanographic texts refer to tsunamis as "seismic sea waves."

Some meteorological conditions, such as deep depressions that cause tropical cyclones, can generate a storm surge, called a meteotsunami, which can raise tides several metres above normal levels. The displacement comes from low atmospheric pressure within the centre of the depression. As these storm surges reach shore, they may resemble (though are not) tsunamis, inundating vast areas of land.

How Tsunami is generated:

The term tsunami comes from the Japanese composed of the two words tsu meaning "harbor" and  nami, meaning "wave".  Tsunami are sometimes referred to as tidal waves. In recent years, this term has fallen out of favor, especially in the scientific community, because tsunami actually have nothing to do with tides. The once-popular term derives from their most common appearance, which is that of an extraordinarily high tidal bore. 


Tsunami and tides both produce waves of water that move inland, but in the case of tsunami the inland movement of water is much greater and lasts for a longer period, giving the impression of an incredibly high tide. Although the meanings of "tidal" include "resembling" or "having the form or character of" the tides, and the term tsunami is no more accurate because tsunami are not limited to harbours, use of the term tidal wave is discouraged by geologists and oceanographers. There are only a few other languages that have an equivalent native word. 


In the Tamil language, the word is aazhi peralai. In the Acehnese language, it is ië beuna or alôn buluëk (Depending on the dialect. Note that in the fellow Austronesian language of Tagalog, a major language in the Philippines, alon means "wave".) On Simeulue island, off the western coast of Sumatra in Indonesia, in the Defayan language the word is smong, while in the Sigulai language it is emong.

Historic tsunami
As early as 426 B.C. the Greek historian Thucydides inquired in his book History of the Peloponnesian War about the causes of tsunami, and was the first to argue that ocean earthquakes must be the cause.[5][6]

The cause, in my opinion, of this phenomenon must be sought in the earthquake. At the point where its shock has been the most violent the sea is driven back, and suddenly recoiling with redoubled force, causes the inundation. Without an earthquake I do not see how such an accident could happen.[12]

The Roman historian Ammianus Marcellinus (Res Gestae 26.10.15-19) described the typical sequence of a tsunami, including an incipient earthquake, the sudden retreat of the sea and a following gigantic wave, after the 365 A.D. tsunami devastated Alexandria.

While Japan may have the longest recorded history of tsunamis, the sheer destruction caused by the 2004 earthquake and tsunami event mark it as the most devastating of its kind in modern times, killing around 230,000 people. The Sumatran region is not unused to tsunamis either, with earthquakes of varying magnitudes regularly occurring off the coast of the island.

Specifications:

Tsunamis cause damage by two mechanisms: the smashing force of a wall of water travelling at high speed, and the destructive power of a large volume of water draining off the land and carrying all with it, even if the wave did not look large.

While everyday wind waves have a wavelength (from crest to crest) of about 100 metres (330 ft) and a height of roughly 2 metres (6.6 ft), a tsunami in the deep ocean has a wavelength of about 200 kilometres (120 mi). Such a wave travels at well over 800 kilometres per hour (500 mph), but owing to the enormous wavelength the wave oscillation at any given point takes 20 or 30 minutes to complete a cycle and has an amplitude of only about 1 metre (3.3 ft). This makes tsunamis difficult to detect over deep water. Ships rarely notice their passage.

As the tsunami approaches the coast and the waters become shallow, wave shoaling compresses the wave and its velocity slows below 80 kilometres per hour (50 mph). Its wavelength diminishes to less than 20 kilometres (12 mi) and its amplitude grows enormously. Since the wave still has the same very long period, the tsunami may take minutes to reach full height. Except for the very largest tsunamis, the approaching wave does not break, but rather appears like a fast-moving tidal bore. Open bays and coastlines adjacent to very deep water may shape the tsunami further into a step-like wave with a steep-breaking front.

When the tsunami's wave peak reaches the shore, the resulting temporary rise in sea level is termed run up. Run up is measured in metres above a reference sea level. A large tsunami may feature multiple waves arriving over a period of hours, with significant time between the wave crests. The first wave to reach the shore may not have the highest run up.

bolides.


How Tsunami is Detected:

To help identify and predict the size of a tsunami, scientists can look at the size and type of the underwater earthquake that precedes it. That is often the first information they receive, because seismic waves travel faster than tsunamis.


This information is not always helpful, however, because a tsunami can arrive within minutes after the earthquake that triggered it. And not all earthquakes create tsunamis, so false alarms can and do happen.


That’s where special open-ocean tsunami buoys and coastal tide gauges can help—by sending real-time information to tsunami warning centers in Alaska and Hawaii. In areas where tsunamis are likely to occur, community managers, educators and citizens are being trained to provide eye-witness information that is expected to aid in the prediction and detection of tsunamis.

Obama Administration Revokes Last-Minute Bush Assault on Endangered Species Act

The Obama administration today revoked a controversial last-minute rule imposed by the Bush administration, which effectively gutted the Endangered Species Act and ended vital protections for threatened and endangered species.

The Bush rule made it unnecessary for federal agencies to consult with professional scientists at the U.S. Fish and Wildlife Service or the National Marine Fisheries Service—the two agencies that administer the Endangered Species Act—before taking any action that might affect threatened or endangered species. Today’s action by the Obama administration restores those important safeguards by reinstating the mandatory consultation procedure.

U.S. Commerce Secretary Gary Locke and Interior Secretary Ken Salazar announced their joint decision to revoke the Bush rule that undermined the ESA.

“By rolling back this 11th-hour regulation, we are ensuring that threatened and endangered species continue to receive the full protection of the law,” Salazar said. “Because science must serve as the foundation for decisions we make, federal agencies proposing to take actions that might affect threatened and endangered species will once again have to consult with biologists at the two departments.”

On March 3, President Obama directed Locke and Salazar to review the Bush administration’s Section 7 regulation of the Endangered Species Act, which governs interagency consultation. Congress, in the 2009 Omnibus Appropriations Act, specifically authorized the two secretaries to revoke the regulation.

Locke and Salazar also said their two departments will conduct a joint review of the 1986 consultation regulations to determine if any improvements should be proposed.

The decision by Locke and Salazar was hailed as a victory by environmentalists.

"The Bush rules would have allowed agencies with little or no wildlife expertise to make decisions that could mean life or death for animals like the polar bear,” said Sierra Club Executive Director Carl Pope in a statement. “Today's decision restores the important protections for species and their habitats offered by one of our nation's most fundamental environmental laws.”

Five Ways to Help Save the Planet in 30 Minutes or Less

Every day you hear more and more about the environmental problems mankind is facing. You wonder what you can do to help, and how you'll ever find the time.

Take heart. You may not be able to reduce global warming, end pollution and save endangered species single-handedly, but by choosing to live an earth-friendly lifestyle you can do a lot every day to help achieve those goals. And it won't require you to give up your job or ignore your family.

To get you started, here are five simple things you can do—in 30 minutes or less—to help protect the environment and save this little blue ball we call home.

And if you've already adopted green living, how about sharing your ideas with us? Look for Readers Respond: How have you adopted green living? at the end of "Five Ways to Help Save the Planet in 30 Minutes or Less." Your ideas could encourage others to follow your green living path.