What happened is called air burst today. At the time, the energy involved was estimated to be between 10 and 30 megatons of TNT, depending on the height in which the air burst happened. Simulations that have been done with modern computers have found that the energy involved was probably between 3 and 5 megatons of TNT. Taking 15 megatons, this would mean that the energy involved was 1.000 times that of the atomic bomb dropped on Hiroshima, in 1945. The shock wave is considered to be that of an earthquake with a magnitude of 5.0 on the Richter scale. For these reasons, the Tunguska event is considered the largest impact event on Earth in recorded history.
At first, there was no interest in the event. Over a decade after the event, Leonid Kulik, a Russian mineralogist led an expedition to the area. In his expedition of 1921 and 1922, he only got to Kansk, which is away from the "epicenter" of the event. In 1927, Kulik reached the region where the event happened, in 1938 he ordered aerial photos be taken.
Kulik's expedition is the first recorded expedition to the area. Since then, there were many expeditions; over 1,000 articles have been published on the event; most of them are in Russian language.
There were two other expeditions to the area: one in 1958, the other in 1963.
Today, there is no definite explanation for what caused the explosions, or for what happened. There are different theories, though.
A meteorite hit the area. The most probable is an asteroid or comet of low density, and a diameter of between and . The object exploded in a height of 7 to 14 km above ground; for this reason there is no impact crater. The problem with this theory is that meteorites of this type usually do not reach low levels of the atmosphere. Meteoroids, which contain more iron have a higher chance of reaching low levels of the atmosphere, but they do not cause such devastating explosions.
Lake Cheko is a small freshwater lake, about from the center of the event. The lake does not show on maps of the area which are older than about 1928. Before 1908, it seems to be unknown. The lake is rectangular; it is 708 metres long, 364 m wide, and about 50 m deep. In 1999, Luca Gasperini did a study on the sediments in the lake, and found that the lake predates the event of 1908. In 2007, National Geographic cites him as he states that it is possible the lake formed as an impact crater.This is disputed due to the spread of trees, destroyed from the widely accepted Meteorite explosion.
The other theory is that the event has a geophysical cause: About 10 million ton of natural gas exploding would have the effect that was observed. The problem with this theory is that eyewitnesses spoke of a very bright light that could be seen from very far away. A natural gas explosion does not produce a bright light.
Grand jury
A grand jury is a legal body which has the power to conduct official proceedings to investigate possible criminal conduct. They also decide whether criminal charges should be brought. A grand jury may subpoena evidence and may compel the sworn testimony of witnesses who appear before it. Grand juries are made up of from 16 to 23 people in the United States. They meet for a period of one month up to a year. However, jurors may only have to meet for a few days each month. The juries meet in private. The suspected person, called a suspect, is not usually present. About half the state in the US do not regularly use grand juries. A preliminary hearing may be used instead. The Fifth Amendment to the United States Constitution requires the use of grand juries by the federal legal system for all capital and "infamous crimes" (cases involving treason, certain felonies or gross moral turpitude).
In 1166 an enactment of King Henry II of England, called the Assize of Clarendon, called for "the oath of *twelve men from every hundred and four men from every vill" to meet and decide who was guilty of robbery, theft or murder. It was the early ancestor of the jury system and of the grand jury. The United Kingdom abolished grand juries in 1933. Many of their former colonies including
Canada, Australia and New Zealand have also stopped using them. The United States is one of the few remaining countries that uses the grand jury.
Grand juries are called by a federal judge and are required to supervise them. But judges almost never interfere. The grand jury is led by a federal prosecutor. He cannot testify or be present while the jury deliberates. But most federal grand juries will return any indictment presented to it. This led to the famous saying "a prosecutor can get a grand jury to indict a ham sandwich." They can subpoena anything they want with very few restrictions. In United States v. R. Enterprises, Inc., 498 U.S. 292 (1991), the Supreme Court of the United States ruled "federal grand jury subpoenas are presumed to be reasonable and the burden of showing unreasonableness is on the recipient."
A grand jury, state or federal, has two functions. The first is to go over all evidence of criminal wrongdoing and to issue an indictment only if there is enough evidence. Their other purpose is to investigate and help the prosecutor gather evidence. Critics claim grand juries have failed to do both.
Vault (gymnastics)
A vault is an apparatus that male and female gymnasts perform on. A vault is included in gymnastics competitions such as the olympics. The gymnasts first run before they flip on the vault. Either the male or female gymnast perform a flip in the air and land on the floor. When the gymnast lands on the floor, he or she has to be in balance.
Early forms of the vault were invented by German Friedrich Ludwig Jahn. The apparatus itself originated as a "horse", much like the pommel horse but without the handles. It was sometimes called a "vaulting horse". The horse was set up with its long side perpendicular to the run for women, and parallel for men. The vaulting horse was the apparatus used in the Olympics for over a century It began with the 1896 Summer Olympics and ending with the Gymnastics at the 2000 Summer Olympics.
Following a number of problems, International Gymnastics Federation (FIG) changed the apparatus. They did it for both safety reasons and for better acrobatics. The 2001 World Artistic Gymnastics Championships were the first international competition to make use of the "vaulting table". This was an apparatus made by Dutch gymnastics equipment company Janssen-Fritsen since the mid-1990s. It features a flat, larger, and more cushioned surface almost parallel to the floor. It slopes downward at the end closest to the springboard. Gymnasts nicknamed it the "tongue".
Web design
Web design is a profession where a person designs a web page or a web site. The web page can have graphics, music, animations, and many other things on it. Some web design is done for businesses, and some is done for individual people. Some web designs are used a lot and have standard templates that are free for people to use.
People who design web pages are called web designers. Web designers use HTML or Dynamic HTML ("DHTML"), Cascading Style Sheets ("CSS"), JavaScript, and many other technologies to make their pages. Web designers can make their pages on the Internet using website building software, or offline on their computer. Web designers in the United States of America can earn between $31,650 and $69,510 a year, with a median salary of $46,327.
Web design includes layouts, colors, graphics, fonts, and content.