An Astronomy History Timeline - from the Big Bang until today
It's hard, at times, to think of the universe in terms of an astronomy history timeline.. After all, as human beings, we're used to time frames measured in days, weeks, months, years, and lifetimes…and on the scale of astronomy, all our usual time reference points just fall utterly short.
Astronomy history timeline – the beginning of it all
Right now, the current thinking on the age of the universe, based off of the COBE (Cosmic Background Explorer) and the MAP follow on estimates, are that the universe, or the parts of it we can observe directly, are 14.7 billion years ago. So, any history of the universe, any astronomy history timeline, starts with that.
Now, 14.7 billion years is a long time. The entire Earth is about 5.5 billion years old. Life on Earth dates back about 3 billion years, and multi-cellular life only reliably dates back to half a billion years. Our species in recognizable form only dates back to about three quarters of a million years, and our first Neolithic evidence of any kind of astronomical observations (from cave paintings) date back to about 20,000 years ago, and formally recorded history is only 8,000 years old.
On the scale of an astronomy history timeline, human history is tiny. Even so, there are some dates of significance.
Somewhere around 8,000 years ago, the land bridge between Britain and Europe washed away as the glaciers receded – this was probably the first real instance of global warming and coastal flooding in human history! However, also dating back to this time period are the remains of menhirs and stone structures that were aligned to have certain stars show through them on certain days of the year, one of the first attempts at using the stars and sky as a calendar for crops and cattle grazing. An interesting challenge in putting together an astronomy history timeline is trying to backtrack through the synodic periods and anapsis processes to figure out which stars were being used 8,000 years ago for these purposes. This is complicated because the ground also shifts due to earthquakes, erosion and modern construction.
Astronomy history timeline – solar and lunar calendars
Around 5,000 years ago, moving beyond stars on stone structures, we also got to combined solar and lunar calendars. The lunar calendar is easier to devise the first time around, but it's inaccurate without a check against the solar cycle as well – there are thirteen and a fraction lunar months in the solar calendar year, and one of the chief developments in astronomical history was using the solar calendar to correct for the lunar calendar's need for a leap month.
Skipping forward again, about 3500 years ago, we have the first record of the Greek language, which eventually became the language of astronomy in Europe, and it's in this language that we had Eratosthenes calculation of the diameter of the Earth dating back to 2300 years ago, and his contemporary Aristarchus first proposed an heliocentric model of the universe. A century and a half later, we have Hipparchus's first star catalog – the first accurate star map in antiquity. Ptolemy proposed the Geocentric model of the universe two centuries later, and it wasn't until Copernicus in 1543 AD that a competing theory had any traction in the scientific establishment!
Astronomy history timeline – the telescope is used to look at the stars
The first use of a telescope to look at the heavens – one of the two most important astronomical instruments, was done by Galileo Galilei in 1609. He discovered the moons of Jupiter, the rings of Saturn, and sunspots with this device. The second important astronomical device is the spectroscope, which, with Principia Mathematica and the law of universal gravitation, provide the fundamental understanding of orbital mechanics, and the ability to accurately measure the color (and later, with the Hertzprung Russel diagram, temperatures) of stars, a key technique for figuring out their distance, and age.In 1905, Albert Einstein shook the astronomical world to its core by predicting that Mercury's orbit would be slightly slower than Newton's classical mechanics would indicate, and that gravity would bend light. Both of these predictions were validated by clinical observation, and the universe changed dramatically.
Astronomy hasn’t stopped in the last century, either… It's still adding more knowledge about our universe every year than has accumulated in the century prior.
It's an exciting time to be a stargazer.
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