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The History Of Astronomy

The History Of Astronomy



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.
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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.
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Credits: Ron Miller
Credits: Nasa/Shutterstock/Storyblocks/Elon Musk/SpaceX/Esa
Credits: Flickr

#InsaneCuriosity #Astronomy #Space

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What Is Our Place In The Milky Way?

What Is Our Place In The Milky Way?



What is our place in the Milky Way? And our place in the Universe? In ancient times, many people had the idea our planet Earth to be at the centre of the Universe, as stated by Aristotle and Ptolomeus in their ptolemaic – aristotelic concept of universe: according to this model, Earth is at the center of the universe and all the other celestial bodies orbit around it. Today lots of people think the same. But is this really the case? To answer this question, let’s try to to a travel in the universe, through space and time; we will start our travel from our planet to reach, in the end, the extreme boundaries of the universe.
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During the 1600s, Galileo Galilei, the famous Italian astronomer, was one of the first people, during modern age, to have some doubts about the geocentric model of universe: thanks to telescopic observations, he was able to demonstrate our Earth is not at the rotation centre of planets and the Sun, but really it is the Sun itself. Moreover, observing planet Jupiter, he discovered that the giant planet is the rotation center for its moons. So, Galileo became aware that the center of the Solar System was the Sun, not the Earth!

The Solar System is made by a star, the Sun, eight planets and different types of minor celestial bodies, like comets, asteroids and dwarf planets.
Well, the Earth isn’t at the center of the Solar System, maybe is the closest planet to our Sun? No it isn’t, because it is only the third planet from the Sun: the closest planet to our star is Mercury, followed by Venus and then Earth. The Earth moves around the Sun, our star, just like all the other celestial bodies in the Solar System do: this implies that the Sun, and not our planet, is the center of rotation of the Solar System! The Earth takes a year, 365 days, to travel its orbit, and its average distance from the Sun is 150 million kilometers, which is the measure unit of distances in the Solar System known as the astronomical unit and abbreviated AU. Why do we talk about average distance? Because the orbit traveled by the Earth around the Sun is not circular but elliptical, and this means that there will be an aphelion (i.e. the point of the Earth’s orbit farthest from the Sun, just over 1 AU away from it) and a perihelion (the point of Earth’s orbit closest to the Sun, just under 1 AU). An alternative way to define the astronomical unit passes through the light time, in particular we can say that the average distance Earth – Sun is equal to about 8 light minutes: this means that sunlight takes 8 minutes to arrive on Earth, so that the sunlight we see at a certain moment is not that of that moment but it is the sunlight which left from the Sun 8 minutes earlier! In other words: if the sun went out for example at 2.30 pm, we would only notice it at 2.38 pm! Or again: if you could travel aboard the Star Wars Millennium Falcon it would take you only 8 minutes to travel from the Sun to the Earth (when in reality it takes a few years). To give a more concrete idea of the dimensions of the Solar System: if the Sun were a sphere with a diameter of 14 cm, Pluto would be at 700 m from the Sun, like seven regular soccer fields!

The nearest celestial body to Earth is the Moon, our satellite: to reach it you should take three days off! It’s the same time taken by Apollo astronauts to cover the distance of nearly 400 thousand kilometers that separate Moon and Earth. But if you had Star Trek Enterprise, and travel at maximum curvature, you would only take less than 2 seconds to reach the Moon!

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“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. ( in its different versions such as 1.0, 2.0, 3,0, and 4.0 – permitting commercial sharing with attribution given in each picture accordingly in the video.”

Credits: Mark A. Garlick / markgarlick.com
Credits: Ron Miller
Credits: Nasa/Shutterstock/Storyblocks/Elon Musk/SpaceX/ESA
Credits: Flickr
Credits: ESO

#InsaneCuriosity #MilkyWay #Galaxies

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