A spacecraft is a vehicle or machine designed to fly in outer space. A type of artificial satellite, spacecraft are used for a variety of purposes, including communications, Earth observation, meteorology, navigation, space colonization, planetary exploration, and transportation of humans and cargo. All spacecraft except single-stage-to-orbit vehicles cannot get into space on their own, and require a launch vehicle (carrier rocket). On a sub-orbital spaceflight, a space vehicle enters space and then returns to the surface without having gained sufficient energy or velocity to make a full Earth orbit. For orbital spaceflights, spacecraft enter closed orbits around the Earth or around other celestial bodies. Spacecraft used for human spaceflight carry people on board as crew or passengers from start or on orbit (space stations) only, whereas those used for robotic space missions operate either autonomously or telerobotically. Robotic spacecraft used to support scientific research are space probes. Robotic spacecraft that remain in orbit around a planetary...

The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of Australia). The Moon is a planetary-mass object with a differentiated rocky body, making it a satellite planet under the geophysical definitions of the term and larger than all known dwarf planets of the Solar System. It lacks any significant atmosphere, hydrosphere, or magnetic field. Its surface gravity is about one-sixth of Earth's at 0.1654 g, with Jupiter's moon Io being the only satellite in the Solar System known to have a higher surface gravity and density. The Moon orbits Earth at an average distance of 384,400 km (238,900 mi), or about 30 times Earth's diameter. Its gravitational influence is the main driver of Earth's tides and very slowly lengthens Earth's day. The Moon's orbit around Earth has a sidereal period of 27.3 days. During each synodic period of 29.5 days, the amount of visible surface illuminated by the Sun varies...

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Science is a systematic endeavor that builds and organizes knowledge in the form of testable explanations and predictions about the universe.Science may be as old as the human species, and some of the earliest archeological evidence for scientific reasoning is tens of thousands of years old. The earliest written records in the history of science come from Ancient Egypt and Mesopotamia in around 3000 to 1200 BCE. Their contributions to mathematics, astronomy, and medicine entered and shaped Greek natural philosophy of classical antiquity, whereby formal attempts were made to provide explanations of events in the physical world based on natural causes.: 12  After the fall of the Western Roman Empire, knowledge of Greek conceptions of the world deteriorated in Western Europe during the early centuries (400 to 1000 CE) of the Middle Ages, but was preserved in the Muslim world during the Islamic Golden Age and later by the efforts of Byzantine Greek scholars who brought Greek manuscripts from the dying Byzantine Empire to Western Europe in the Renaissance. The recovery...

Orion is a prominent constellation located on the celestial equator and visible throughout the world. It is one of the most conspicuous and recognizable constellations in the night sky. It is named after Orion, a hunter in Greek mythology. Its brightest stars are the blue-white Rigel (Beta Orionis) and the red Betelgeuse (Alpha Orionis). Characteristics Orion is bordered by Taurus to the northwest, Eridanus to the southwest, Lepus to the south, Monoceros to the east, and Gemini to the northeast. Covering 594 square degrees, Orion ranks twenty-sixth of the 88 constellations in size. The constellation boundaries, as set by Belgian astronomer Eugène Delporte in 1930, are defined by a polygon of 26 sides. In the equatorial coordinate system, the right ascension coordinates of these borders lie between 04h 43.3m and 06h 25.5m , while the declination coordinates are between 22.87° and −10.97°. The constellation's three-letter abbreviation, as adopted by the International Astronomical Union in 1922, is "Ori".Orion is most...

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Ronald "Ronnie" Dean Coleman (born May 13, 1964) is an American retired professional bodybuilder. The winner of the Mr. Olympia title for eight consecutive years, he is widely regarded as either 'the greatest' or one of the two greatest bodybuilders of all time along-with Arnold Schwarzenegger and as the most dominant bodybuilding physique ever to grace the stage. Winner of 26 IFBB professional titles, he is also renowned for his combination of size and conditioning, dominant body-parts and extremely heavy workouts, making him the strongest bodybuilder and Mr. Olympia of all time. Early life Ronnie Dean Coleman was born in Monroe, Louisiana, on May 13, 1964. He graduated cum laude from Grambling State University in 1984 with a BSc in accounting. While there, he played football as a middle linebacker with the GSU Tigers under coach Eddie Robinson. After graduation, he failed to find work as an accountant and instead went to work at Domino's Pizza, where he would eat the complimentary pizza every day due to being so poor that he could barely afford to eat outside of work. He then became a police officer...

An X-ray, or, much less commonly, X-radiation, is a penetrating form of high-energy electromagnetic radiation. Most X-rays have a wavelength ranging from 10 picometers to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz (3×1016 Hz to 3×1019 Hz) and energies in the range 145 eV to 124 keV. X-ray wavelengths are shorter than those of UV rays and typically longer than those of gamma rays. In many languages, X-radiation is referred to as Röntgen radiation, after the German scientist Wilhelm Conrad Röntgen, who discovered it on November 8, 1895. He named it X-radiation to signify an unknown type of radiation. Spellings of X-ray(s) in English include the variants x-ray(s), xray(s), and X ray(s). The most familiar use of X-rays is checking for fractures (broken bones), but X-rays are also used in other ways. For example, chest X-rays can spot pneumonia. Mammograms use X-rays to look for breast cancer. ...

In archaeology, Cave paintings are a type of parietal art (which category also includes petroglyphs, or engravings), found on the wall or ceilings of caves. The term usually implies prehistoric origin, and the oldest known are more than 40,000 years old (art of the Upper Paleolithic) and found in the caves in the district of Maros (Sulawesi, Indonesia). The oldest are often constructed from hand stencils and simple geometric shapes. More recently, in 2021, cave art of a pig found in Sulawesi, Indonesia, and dated to over 45,500 years ago, has been reported.A 2018 study claimed an age of 64,000 years for the oldest examples of non-figurative cave art in the Iberian Peninsula. Represented by three red non-figurative symbols found in the caves of Maltravieso, Ardales and La Pasiega, Spain, these predate the appearance of modern humans in Europe by at least 20,000 years and thus must have been made by Neanderthals rather than modern humans.In November 2018, scientists reported the discovery of the then-oldest known figurative art painting, over 40,000 (perhaps as old as 52,000) years old, of an unknown animal, in the cave of Lubang Jeriji Saléh on the Indonesian...