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frame Galileo GalileiGalileo Galilei ( Pisa, February 15, 1564 Arcetri, January 8, 1642), was a Tuscan astronomer, philosopher, and physicist who is closely associated with the scientific revolution. His great achievements include perfecting the telescope, a variety of astron (1564-1642) crafted his own telescope and discovered that our Moon had craters, that Jupiter had moons, that the Sun had spots, and that Venus had phases like our Moon. Galileo claimed these observations were comprehensible only within the Copernican system, in which the planets revolved around the Sun and not the Earth, as was commonly believed then.
Ancient astronomers were able to differentiate between stars and planets; as Stars remain relatively fixed over the centuriesA century is one hundred of something, usually one hundred consecutive years, or 100 runs in cricket, or a bicycle ride of 100 miles in a day. In all dating systems, Centuries are numbered ordinally. Thus, one speaks of the First Century of the Common Era, while planets will move an appreciable amount during a comparatively short time.
Early cultureThe word culture comes from the Latin root colere (to inhabit, to cultivate, or to honor). In general it refers to human activity; different definitions of culture reflect different theories for understanding, or criteria for valuing, human activity.s identifed celestial objects with godThis article is about a system of myths. For the 1942 book Mythology see its author Edith Hamilton. A mythology is a relatively cohesive set of myths: stories that comprise a certain religion or belief system. What is mythology? Myths are generally stories and spiritA spirit or spiritual being is a non-corporeal entity found in many religions and belief systems throughout the world. The word has many connections to the concept of the soul, with the difference that a spirit is not necessarily linked to a human or othes. They related these objects (and their movements) to phenomena such as rain, drought, seasons, and tides. It is generally believed that the first "professional" astronomers were priests ( Magi), and that their understanding of the " heavens" was seen as " divine", hence astronomy's ancient connection to what is now called astrology. Ancient constructions with astronomical alineation s (such as Stonehenge) probably fulfilled both astronomical and religious functions.
Calendars of the world have usually been set by the Sun and Moon (measuring the day, month and year), and were of importance to agricultural societies, in which the harvest depended on planting at the correct time of year. The most common modern calendar is based on the Roman calendar, which divided the year into twelve months of alternating thirty and thirty-one days apiece. Various Roman emperors altered the calendar subsequently. Julius Caesar instigated calendar reform and created the leap year.Greeks made some important contributions to astronomy, but the progress was mostly stagnant in medieval Europe, but flourished meanwhile in the Arab world. The late 9th century Islamic astronomer al-Farghani (Abu'l-Abbas Ahmad ibn Muhammad ibn Kathir al-Farghani) wrote extensively on the motion of celestial bodies. His work was translated into Latin in the 12th century. In the late 10th century, a huge observatory was built near Tehran, Iran, by the astronomer al-Khujandi who observed a series of meridian transits of the Sun, which allowed him to calculate the obliquity of the ecliptic. In Persia, Omar Khayyam (Ghiyath al-Din Abu'l-Fath Umar ibn Ibrahim al-Nisaburi al-Khayyami) compiled many tables and performed a reformation of the calendar that was more accurate than the Julian and came close to the Gregorian.
The renaissance came to astronomy with the work of Copernicus, who proposed a heliocentric system. His work was defended, expanded upon and corrected by the likes of Galileo Galilei and Kepler. The latter of these was the first to provide a system which described correctly the details of the motion of the planets with the Sun at the center. He didn't understand the reasons behind the laws he wrote down, however, and it was left to Newton's invention of celestial dynamics and his law of gravitation, the final explanation of the motions of the planets. Astrophysics was only possible once it was understood that the elements that made up the "celestial objects" were the same that made up the Earth, and that the same laws of physics applied.
Stars were found much later to be far away objects, and with the advent of spectroscopy it was proved that they were similar to our own sun, but with a range of temperatures, masses and sizes. The existence of our galaxy, the Milky Way, as a separate group of stars was only proven in the 20th century, along with the existence of "external" galaxies, and soon after, the expansion of the universe seen in the recession of most galaxies from us.
Cosmology, a discipline that has a large intersection with astronomy, made huge advances during the 20th century, with the model of the hot big bang heavily supported by the evidence provided by astronomy and physics, such as the cosmic microwave background radiation, Hubble's law and cosmological abundances of elements.