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The History Of Astronomy : How Humans First Mapped The Night Sky
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The History Of Astronomy : How Humans First Mapped The Night Sky

Who Are We and Where Do We Come From?

Introduction to Astronomy

  • Astronomy seeks to answer fundamental questions about humanity's existence, the universe's origins, and celestial bodies' movements.
  • The science of astronomy has captivated human imagination since ancient times, intertwining with religious and cosmological beliefs.

Early Observations and Developments

  • The first astronomers distinguished planets from stars through careful observations, leading to early predictions about celestial events.
  • Humanity's curiosity was sparked by natural phenomena like sunrises, sunsets, lunar phases, comets, and eclipses. These were seen as divine occurrences in ancient times.

Ancient Greek Contributions to Astronomy

Understanding Earth's Shape

  • By the 6th century BCE, Greek philosophers provided evidence that Earth is spherical based on varying night skies observed from different locations.
  • They accurately calculated Earth's circumference using shadow measurements at two locations; their estimate was approximately 46,250 kilometers compared to the actual value of 40,075 kilometers.

Supernova Observations

  • In 185 CE, Chinese astronomers documented a supernova explosion; notable ones include a bright event in 1054 CE visible even during daylight hours.
  • The concept of galaxies beyond the Milky Way emerged only in the last century; earlier views considered them as parts of our galaxy rather than separate entities.

The Shift from Geocentric to Heliocentric Models

Historical Perspectives on Celestial Mechanics

  • Before the 16th century, the geocentric model placed Earth at the solar system's center; this view conflicted with certain astronomical observations like retrograde motion of planets.
  • Nicolaus Copernicus proposed a heliocentric model in 1543 where planets orbit around the Sun—this explained previously confusing planetary paths effectively.

Renaissance Advances in Astronomy

  • The Renaissance period saw revolutionary ideas emerge regarding planetary motions thanks to Tycho Brahe and Johannes Kepler’s work which laid groundwork for Newton’s gravitational theory.

Technological Innovations and Ancient Monuments

Impact of Telescopes on Astronomy

  • Galileo Galilei popularized telescopes in the early 17th century for celestial studies; he discovered Jupiter's four largest moons known today as Galilean moons.

Astronomical Alignments in Ancient Structures

  • Ancient monuments like Egypt’s pyramids and Stonehenge exhibit astronomical orientations linked to various celestial phenomena indicating advanced knowledge among ancient civilizations about cosmic events.

Hipparchus and the Foundations of Astronomy

Hipparchus's Contributions to Astronomy

  • Hipparchus made significant contributions, but his initial premises included questionable numerical values, such as assuming a 87° angle between the Sun and Moon at quarter Moon.
  • He estimated the Sun's distance to be about 19 times that of the Moon, while the actual ratio is approximately 389.
  • Hipparchus discovered precession, which is the slow eastward motion of stars around the zodiac due to Earth's axial wobble over 25,772 years.
  • His observations were based on fixed stars relative to eclipsed Moons and compared with earlier eclipse data from predecessors.
  • Historians debate whether Babylonian awareness of precession influenced Hipparchus or if differing equinox norms were merely alternative conventions.

Galileo's Revolutionary Observations

  • Galileo Galilei is renowned for his telescope innovations; in 1609 he observed various celestial phenomena including lunar topography and sunspots.
  • His observations of Venus phases indicated it orbits the Sun, while discovering Jupiter’s four satellites challenged Earth-centric views of astronomy.
  • These findings dismantled long-held beliefs that all celestial bodies revolved around Earth, marking a pivotal shift in astronomical thought.
  • Galileo combined mathematics with physics to demonstrate universal laws governing both terrestrial and celestial realms, expanding humanity's understanding of the universe.

Kepler's Laws of Planetary Motion

  • In 1609, Johannes Kepler published Astronomia nova, introducing two fundamental laws regarding planetary motion: elliptical orbits and equal area sweeps by planets over equal time intervals.
  • Influenced by Copernicus and Tycho Brahe’s precise observations, Kepler overcame personal doubts to redefine planetary movement away from circular paths centered on Earth.
  • The first law states planets orbit in ellipses with the Sun at one focus; the second law indicates that planets sweep out equal areas in equal times regardless of their position along their orbit.

Advancements in Astronomy Over Centuries

  • The evolution of telescopes has allowed astronomers to reconstruct cosmic history significantly over the past 400 years.
  • Eclipses are now understood as alignments rather than omens; comets are recognized as icy bodies rather than mysterious entities.
  • Babylonian astronomers identified five visible planets (Mercury, Venus, Mars, Jupiter, Saturn), distinguishing them from stars based on their unique movements.

Hubble's Impact on Cosmology

  • Edwin Hubble revolutionized our understanding of the universe in 1923 by demonstrating that Andromeda Nebula exists outside our Milky Way using a large telescope.
  • His discovery led to theories about an expanding universe and laid groundwork for modern cosmological concepts like the Big Bang theory proposed by Georges Lemaître.
  • The evidence supporting this theory includes findings like cosmic microwave background radiation—remnants from an early explosive event shaping our universe.

The Evolution of Astronomy and Technological Advancements

Discovery of Cosmic Microwave Background (CMB)

  • The CMB was discovered accidentally by radio astronomers just five years before the historic Apollo 11 Moon landing in 1969, marking a significant milestone in astronomical research.

Advancements in Telescopes and Observational Techniques

  • Modern telescopes, equipped with large mirrors, have enhanced astronomers' ability to capture light from faint and distant celestial objects across the entire electromagnetic spectrum, including infrared light, radio waves, and X-rays.
  • Advanced techniques and sensitive instruments have enabled direct observations of complex phenomena such as black holes, distant exoplanets, and gravitational waves.

Robotic Space Probes and Data Collection

  • Improvements in satellite launch technology during the latter half of the 20th century facilitated extensive data collection about planets within our solar system through various robotic space probe campaigns like Mariner, Venera, and Voyager.
  • These missions ventured farther than ever before into space, significantly expanding our understanding of planetary science.
Video description

Who we are? Where do we come from and where are we going? How and why was the Universe born? These are some of the eternal questions associated with astronomy that continue to pique human imagination from ancient times to the present day. Astronomy is the science that has as its main purpose the determination of the positions, dimensions and movements of the celestial bodies. So in this video we are going to talk about something magnificent that will help us understand the humanity’s perception over the years about astronomy. Let’s analyze and get deep into the history of astronomy. ---- Astronomy is the oldest of the natural sciences and powerfully associated with religious, cosmological, and astrological beliefs. The first astronomers were the ones who could distinguish the planets and the stars due to the fact that they were the first ones that made observations and predictions. From the beginning humanity turned its eyes to the sky full of awe and questions. The sunrise and sunset of the Sun, the phases of the Moon, the alternation of seasons, the movement of other planets in the sky, the appearance of comets and the shocking phenomenon of eclipses, were the first evidence that there is something above that needs to be discovered. That is how astronomy started to develop. These incidents raised our curiosity and made us wonder what are they? Where do they come from? We do know today but imagine in those days… they were like Gods. As early as the 6th century BCE, ancient Greek philosophers documented evidence that Earth was a sphere. They noted that the night sky looked different when seen from various locations on Earth, hinting at our planet's curved surface. They also observed the round shadow of Earth on the Moon during lunar eclipses. These philosophers were even able to calculate the circumference of Earth quite accurately. They did this by measuring the length of the shadow cast by an object at exactly the same time, in two different locations. Taking into account the distance between those two locations and the difference in the lengths of the shadows, they calculated that Earth's circumference was about 46,250 kilometres. That is very close to the real value of 40,075 kilometres! In the year 185, Chinese astronomers became the first to document a supernova. Several supernova explosions have been observed since then, including a particularly bright one in the year 1054, which (at its peak) was four times brighter than planet Venus, one of the brightest objects in the night sky. Some supernovae are even bright enough to be visible during the day! The notion that our own galaxy – the Milky Way – is but one of trillions of other galaxies in the universe only dates back about a century. Before then, nearby galaxies were thought to be cloudy regions of the Milky Way. The first documented observation of the neighbouring Andromeda Galaxy was in the year 964 by a Persian astronomer who described it as a "nebulous smear." For centuries, it was simply known in star charts as the "Little Cloud." Before the 16th century, Earth was commonly thought to be at the centre of the solar system, with all other celestial objects revolving around it. This is known as the geocentric model. This theory, however, did not match some confusing observations made by astronomers, such as the path of planets that appeared to move backwards on their orbits. In 1543, Polish astronomer Nicolaus Copernicus proposed a heliocentric model of the solar system in which the planets orbit the Sun. This model explained the unusual path of planets that astronomers had observed. The new theory was one of many revolutionary ideas about astronomy that emerged during the Renaissance period. The work of astronomers Tycho Brahe and Johannes Kepler led to an accurate description of planetary motions and laid the foundation for Isaac Newton's theory of gravitation. This progress dramatically improved humanity's understanding of the universe. ------------------------------------------------------------------------------------------- "If You happen to see any content that is yours, and we didn't give credit in the right manner please let us know at: Lorenzovareseaziendale@gmail.com and we will correct it immediately" "Some of our visual content is under an Attribution-ShareAlike license. (https://creativecommons.org/licenses/) in it’s different versions such as 1.0, 2.0, 3,0 and 4.0 – permitting comercial sharing with attribution given in each picture accordingly in the video." Credits: Ron Miller Credits: Nasa/Shutterstock/Storyblocks/Elon Musk/SpaceX/Esa Credits: Flickr Video Chapters: 00:00 Introduction 00:24 What is Astonomy? 01:53 Early Astronomy 05:45 Greek Astronomy 08:45 Johannes Kepler #insanecuriosity #astronomy #space