One of the oldest scientific disciplines that has evolved from the humble beginnings of counting stars to the impressive showcase of humankind's technological capabilities is astronomy.

Astronomers are still trying to understand the nature of the universe despite the progress that has been made. As our understanding of the universe has grown, so has the question.

The star- studded sky that our ancestors gazed at turned into a zoo of strange objects as the depths of the sky opened.

Scientists shaped astronomy.

At the same time, the two-dimensional constellations that inspired the imagination of early sky-watchers were reduced to an optical illusion, behind which the swirling of galaxies hurtling through spacetime reveals a story that began with the Big bang.

The story of astronomy and our understanding of the universe began here.

History of astronomy: The beginnings

Most of today's citizens of planet Earth live surrounded by the inescapable glow of modern urban lighting and can't imagine the awe-inspiring presence of the pristine star- studded sky that illuminated the nights for ancient tribes and early civilization. Our ancestors were drawn to that sight because sky-watching was a part of their lives.

The ancient monuments built to reflect the journey of the sun in the sky helped keep track of time and organize life in an age that relied on seasons. The "world's oldest star map," a bronze-age Nebra disk, was discovered thousands of years ago.

According to the European Space Agency, there are similar records from early China. According to the University of Oregon, astronomy is the oldest science and can be considered the first science.

Sky-watching was elevated by ancient Greeks. The first attempt to calculate the distance of Earth to the sun and moon was made by Aristarchus of Samos, who cataloged the positions of over 800. The brightness scale is still used today.

A photograph of the Nebra Disc, one of the earliest known artefacts depicting the night sky.

The Nebra Disc, estimated to be 3,600 years old, is one of the oldest known artefacts depicting the night sky. (Image credit: Frank Vincentz)
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History of astronomy: The arrival of the telescope

The science of astronomy continued to advance during the Middle Ages. The Islamic scholars continued to build on the knowledge of the Ancient Greeks. New tools for measuring the position of objects in the sky have been developed.

The telescope was the first true breakthrough in humankind's exploration of the universe. The development of the technology enabled Galileo to make major strides in the understanding of our solar system.

According to Albert Einstein, Galileo was the father of modern science because he was able to sketch the surface of the moon.

The telescope made astronomy better. The Catholic Church objected to the idea that Earth was not the center of the universe but that the sun and other planets were there.

The first government-funded observatories were established in 1667 and 1675 and were used to help travelers navigate the globe.

Calculating the distance of a nearby star was done in the 18th century.

The stellar position catalogs grew from a few thousand to tens of thousands of stars in the 19th century because of photography. The first pictures of the moon and sun were published in the 19th century.

In the second half of the 19th century, new and completely unexpected avenues of astronomy were opened by the discovery of spectroscopy. Analyzing the chemical composition of the moon and the sun, as well as other stars and even the galaxies, could be done with the help of a telescope. Astronomy was no longer just about where things were located in the universe but also about what they were made of.

people gather around a telescope and look up at the stars in the sky.

Famous astronomer Galileo Galilei showing off his telescope in Venice in a historical engraving. (Image credit: Welcome Images)
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History of astronomy: The boom of the modern era

The rocket-speed technological progress that the world has witnessed since the beginning of the 20th century has made it possible for astronomy to see farther and analyze more precisely.

Improvements in telescope technology in the early 20th century led to questions about whether the universe was synonymous with the Milky Way or only one of many universes in space. The answer to this question was found in the 1920s by American astronomer Edwin Hubble, who was able to distinguish individual stars in the Andromeda nebula. Hubble found that these stars were so far away from us that they are our own Milky Way. The universe suddenly appeared in front of the astronomer.

The other "nebulas" were confirmed to be a part of the universe. According to Science News, the nebulas were speeding away from Earth faster than the farther away they were. The discovery led to the idea that the universe was expanding from the time of the biggest explosion in its history. The big bang theory was created.

The Second World War gave rise to the era of spaceflight and exploration of the universe. The stuff of science fiction would have been a thing a long time ago.

The first satellite was launched by the U.S.S.R. More and more scientific instruments would be installed on satellites and the picture of the environment around Earth would begin to emerge. In 1962, NASA's Mariner 2 became the first craft to visit another planet, Venus, and in 1964, the first radio astronomy satellite made it into space.

The moon landings of the Apollo program ended the space race of the 1960's. For the first time, scientists on Earth were able to hold pieces of rock from another planet. Lunokhod, the U.S.S.R's lunar rover, analyzed 25 lunar soil samples with its onboard instruments.

The first attempt to study the universe from space was made by NASA in 1968. The new tab is open today. It would take more than two decades to get the Hubble Space Telescope off the ground.

Dozens of probes have been sent to study bodies in the solar system since then. The ancient tribesmen would never be able to imagine a star- studded sky like the one we see today.

The grand finale of the eternal endeavor that began thousands of years ago and grew from humble beginnings was the launch of the James Webb Space Telescope. The grand questions of the nature of the universe and our place in it remain elusive because the more questions are arising and the answers are not yet known.

The Hubble Space Telescope flying above Earth pictured below.

The Hubble Space Telescope, launched in 1991, supercharged astronomical research. (Image credit: NASA)
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Types of astronomy

Observational astronomy uses telescopes and cameras to collect data about the night sky while theoretical astronomy uses that data to theorize about how objects and phenomena work.

They complement each other, yet within these two broad categories, modern astronomy includes many subsets, from Astrometry to exoplanetology, that overlap yet help explain the many things astronomer do They all mean what they say.

  • Astrometry: This ancient branch of astronomy concerns precise calculations of the motions of the sun, the moon and the planets. It includes predictions of solar and lunar eclipses and meteor showers. It also includes exoplanetology, a relatively new and very exciting field that concerns itself with the discovery and characterization of planets outside of the solar system. 
  • Planetary astronomy: How did the solar system come to be? This is the central question penetrating planetary astronomy, which focuses on the formation, evolution and death of planets, moons and other objects in the solar system, it also includes planetary geology.  
  • Astrophysics: Astrophysicists apply the laws and theories of physics to astronomical observations. It's an attempt to understand the mechanism behind how the universe was created and how it has and will evolve.
  • Astrochemistry: Astrochemists study the composition and reactions of atoms, molecules and ions in space. 
  • Astrobiology: This emerging and, for now, largely theoretical field of astronomy is the study of life beyond Earth. 
  • Stellar astronomy: The study of the life cycle and structure of the sun and the stars, stellar astronomy concerns the classification of stars, and populations of stars. 
  • Galactic astronomy: astronomers study our galaxy, the Milky Way, while extragalactic astronomers peer outside of it to determine how these groups of stars form, change and die. 
  • Cosmology: Although it's sometimes used to mean astronomy, strictly speaking, cosmology refers to the science of the origin and nature of the universe. The key concept in cosmology is the Big Bang Theory, the most widely accepted explanation of how the universe began. Cosmology also includes purely theoretical subjects including string theory, dark matter and dark energy (opens in new tab), and the notion of multiple universes.

Side by side comparison of the pillars of creation images. The left image from Hubble shows vast billowing dust plumes with some stars piercing through in the background while the JWST image on the right shows a 'crisper' view showing higher contrast in the clouds of dust and many more stars shining through the dust and in the background.

The iconic Pillars of Creation. The Hubble Space Telescope's view on the left, the new James Webb Space Telescope photo on the right. (Image credit: NASA, ESA, CSA, STScI; Joseph DePasquale (STScI), Anton M. Koekemoer (STScI), Alyssa Pagan (STScI).)
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What are optical, infrared and radio astronomy?

The study of different wavelengths of the spectrum is called astronomy. Astronomers need to study different wavelength of light to get a full picture.

Telescopes are used to observe visible light. Outside of the Earth's atmosphere, space-based telescopes like the Hubble Space Telescope can detect the light from the stars. The study of the sky in radio frequencies is called radio astronomy.

The dipole antennas are arranged in several huge circles in the Australian desert.

The Square Kilometer Array's site in Australia will rely on 130,000 Christmas-tree like dipole antennas to listen to radio waves emitted by objects in the most distant universe. (Image credit: SKAO)
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The problem with astronomy

Astronomers only get a snapshot of the planets, stars and galaxies they study. Although there are dozens of different branches of astronomy, many of them must overlap in order to get a full picture of objects that exist for millions to billions of years.

There is a new technology that is set to change astronomy. A range of ground-breaking Earth-based telescopes is set to come online within this decade including the Vera Rubin Observatory all-sky survey, the Extremely Large Telescope and the Square Kilometre Array.

Astronomers will be able to observe objects that have never been seen before.

The difference between astronomy and astrology

an decorated and detailed astronomy and astrology map.

Astrology and astronomy have the same origin but over the past centuries diverged onto irreconcilable paths. (Image credit: Public Domain Pictures/Andrea Stöckel)
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Both astronomy and astrology grew from the same place. Ancient civilizations and early tribesmen believed that by observing the motions of the stars one could learn about the future.

The two disciplines had a close relationship for thousands of years. Astronomers were hired by monarchs to advise on decisions based on the positions of stars and planets.

Astronomy and astrology have grown apart as the scientific method has grown stronger. While astronomy has become the domain of no-nonsense data-driven observations and verifiable predictions relying on the most cutting-edge technology, astrology was reduced to the realm of new-age superstition where less educated future predictors use glasscrystals and simplistic star charts to predict the path of a person'

You could have been born in the other side of the Zodiac.

Jobs in astronomy

You can find information about what it takes to be an astronomer on the website of the International Astronomical Union. There are a lot of useful resources in the Royal Astronomical Society's careers section.

If you are already further down the path and looking for a suitable opening based on your qualifications, the American Astronomical Society has all kinds of openings all over the world.

The highest paying astronomy jobs are listed in the new tab of theSci Journal.

Additional resources

The history of Astrometry, from the earliest times to the emergence of telescopes, is the subject of a three part series by the European Space Agency. The story of the major leaps in astronomer's understanding of the universe in the first half of the 20th century is told in this Science News feature. The Royal Society has published an article about the evolution of astronomy in the post-war era. The Library of Congress has an article about Galileo's role in shaping modern astronomy.


European Space Agency, A history of astrometry - Part I - Mapping the sky from ancient to modern times, September 1, 2019

European Space Agency, A history of astrometry - Part II - Telescopes ignites the race to measure stellar distances, September 1, 2019

European Space Agency, A history of astrometry - Part III - Astrometry moves to space: The mapmakers guide to the galaxy   

The Royal Society, A brief history of astronomy, astrophysics and cosmology 1945-2000, June 9, 2022                                 

ScienceNews, In 20th century, astronomers opened their minds to gazillions of galaxies, February 2, 2017          

The Library of Congress has an article about finding our place in the universe.