Résultats Éditeur "Charles River Editors" dans Sciences exactes

The early history of our planet covers such vast stretches of time that years, centuries, and even millennia become virtually meaningless. Instead paleontologists and scientists who study geochronology divide time into periods and eras. The current view of science is that planet Earth is around 4.6 billion years old. The first four billion years of its development are known as the Precambrian period. For the first billion years or so, there was no life in Earth. Then the first single-celled life-forms, early bacteria and algae, began to emerge.

As the oft-repeated and invariably accurate pearl of wisdom goes, a dog truly is man's best friend. For a long time, people have almost universally loved dogs, and it seems to have been that way for at least tens of thousands of years. When affection is abundantly and consistently expressed, this pure, unspoken, wholesome love is one that is very much requited, and then some. This bond can be demonstrated by the mere existence of pet keepers who unironically refer to themselves as “dog parents,” not merely “dog owners”. 

As soon as man discovered writing, he began engaging in historiography (historical writing and philosophy), but paleoanthropology only really began in the late 1800s. As archaeologists began finding bones in European caves of a human race that was very different than any race in the modern world, the study of paleoanthropology was born. The race of those early humans who were found in the European caves were later termed Neanderthals, and for quite some time, they were believed to have been the race from which many modern humans were directly descended.

The evolutionary path from the original primates to modern man is a long one and has taken many twists and turns, but naturally, as the fossil record grows, scientists gain a more complete understanding of our own mental and physical history in terms of genetics and anatomy. However, the correct order and relationships of the various specimen types are difficult to pin down. 

On April 24, 1990, the Space Shuttle Discovery lifted off from Kennedy Space Center on the Space Shuttle Program’s 35th mission, but this was no ordinary mission. In its payload bay, Discovery was carrying the Hubble Space Telescope, with the objective of putting the telescope into orbit. By the time the Hubble telescope reached orbit, it was already the world’s most famous telescope, but it was also the most scorned. The telescope cost nearly $2 billion more to complete than anticipated, and to make matters worse, the first images it sent back were skewed. 

Project Mercury: The History and Legacy of America’s First Human Spaceflight Program examines the origins behind the missions, the people and spacecraft involved, and the historic results. Along with pictures of important people, places, and events, you will learn about Mercury like never before. 

When people look up into the night sky, the stars seem fixed and immutable, as unchanging as the darkness of space itself, but the truth is that stars are born, live, and die in a never-ending cycle of creation and annihilation. These cycles stretch over such vast spans of time that to short-lived humans, they seem to last forever. No one knows just how many stars there are, but their number is almost beyond comprehension.

Project Gemini is a neglected part of the US space program. Sandwiched between the excitement of Project Mercury and the sending of the first American astronauts to space and the euphoria of the Apollo Moon landings, Gemini was a step forward rather than a dramatic leap. However, this project achieved many important firsts, including the first spacewalk, the first rendezvous and docking between two spacecraft, the first flights of more than one week’s duration, and many more. 

The Pleistocene spans a period from around 2.5 million years ago (mya) to just over 12,000 years ago, and it was an epoch of enormous change on Earth, mainly characterized by climate changes involving fluctuations between periods of extreme heat and long periods of glaciation. This period is commonly known as the Ice Age, despite the fact there were actually a number of separate periods of cold. The Pleistocene Era: The History of the Ice Age and the Dawn of Modern Humans looks at the development of the era, what life on Earth was like, and the origins of archaic humans. 

The question of man’s place in the extended universe has been pondered by every known culture since the beginning of recorded history. Naturally, as technological advances and the creation of flying aircraft became realities, the sighting of UFOs increased, as did the interest in potential contact with aliens. While incidents like the one at Roswell led to conspiracies and a craze among those who insisted the government was hiding proof of extraterrestrials’ existence, governments across the world were actually secretly studying UFO sightings by the mid-20th century.

Mankind's obsession with felines is an enigma in and of itself. Unlike dogs, famously known as man's most excitable, trustworthy, and loyal friend, cats are oftentimes indifferent, guarded, and yet finicky little furry creatures that only yearn for attention and affection when one is neck-deep in work or otherwise preoccupied. And still, people adore them all the same.

The early history of our planet covers such vast stretches of time that years, centuries, and even millennia become virtually meaningless. Instead, paleontologists and scientists who study geochronology divide time into periods and eras. The current view of science is that planet Earth is around 4.6 billion years old. The first four billion years of its development are known as the Precambrian period.

Imagine a feline with the spirit of a lion, the sneakiness of a puma, the terrifying walk of a black bear, and the strong arms of a gorilla. This amazing creature was best known as the saber-toothed tiger, an animal so fearless, it could beat beasts even twice their size! After dinosaurs, few vanished animals are as famous as the woolly mammoths, or in 18th-century scientist George Cuvier’s words, "some kind of extinct elephant".

Today, the Space Race is widely viewed poignantly and fondly as a race to the Moon that culminated with Apollo 11 “winning” the race for the United States. In fact, it encompassed a much broader range of competition between the Soviet Union and the United States that affected everything from military technology to successfully launching satellites that could land on Mars or orbit other planets in the Solar System.

Today, the Space Race is widely viewed poignantly and fondly as a race to the Moon that culminated with Apollo 11 “winning” the race for the United States. In fact, it encompassed a much broader range of competition between the Soviet Union and the United States that affected everything from military technology to successfully launching satellites that could land on Mars or orbit other planets in the Solar System.

It is difficult to ignore the effortless cool of a saber-toothed tiger. The fanged feline was equipped with the savage strength of a lion, the lethal stealth of a puma, the intimidating gait of a black bear, and the strapping, muscular arms of a gorilla. Amazingly, however, those traits did not stand out as much as the long, dagger-like fangs that earned the Smilodon its famous nickname. The saber-toothed tiger, legend has it, was as ferocious as it was fearless, often tackling beasts twice its size. 

At one point or another, just about everyone has heard of the dodo bird, which is almost universally described as a cuddly, whimsical creature renowned for its alleged stupidity. This prehistoric avian had been known for hundreds of years, before it was made popular around the world in Lewis Carroll’s 1865 classic Alice's Adventures in Wonderland.

The acrid stench of asphalt and sulfur singes the hairs of people’s nostrils, and when the blustering winds subside, the potent miasma lingers in the air. To the untrained eye, the La Brea Tar Pits seem to be nothing more than simply pools of thick, viscous black sludge...The pit’s contents have spelled the doom for a countless number of creatures both large and small, from legions of insects to mighty mastodons, mammoths, and snarling saber-toothed cats from the Pleistocene Era. La Brea Tar Pits are considered by many scientists to be among the greatest finds in modern history.

Standing around 10 feet tall and weighing several tons, woolly mammoths seem like the stuff of legend, but ancient cave art indicated that unlike dinosaurs, woolly mammoths were contemporaries of early humans, with the last ones going extinct only about 4,000 years ago. All of that explains why people have long been fascinated by woolly mammoths and have even envisioned bringing them back to life via genetics sometime in the future.

Today, the Space Race is widely viewed poignantly and fondly as a race to the Moon that culminated with Apollo 11 "winning" the race for the United States. In fact, it encompassed a much broader range of competition between the Soviet Union and the United States that affected everything from military technology to successfully launching satellites that could land on Mars or orbit other planets in the solar system. Moreover, the notion that America "won" the Space Race at the end of the 1960s overlooks just how competitive the Space Race actually was in launching people into orbit.