Astronomy is the study of celestial objects and phenomena throughout our universe. It is one of the oldest scientific disciplines and began with counting stars and naming constellations.
Man has looked to the heavens to navigate the seas, as a guide for when to plant crops, and last but not least, to seek to answer the burning questions of where we came from and how we got here.
As a matter of fact, according to the University of Oregon, astronomy may well be the first science since it is the one for which the oldest written documentation exists.
Circa 1,000 B.C, the Assyro-Babylonians methodically observed and recorded motions of celestial bodies, and the ancient Greeks further advanced the study of the universe.
Aristarchus of Samos made the first, though inaccurate, attempt to calculate the distance of the sun and moon to the Earth. Hipparchus, who is considered by some to be the father of empirical astronomy, listed the positions of over 800 stars using only the naked eye. He also invented a scale to measure the brightness of stars. This is called the magnitude of scale. He assigned the brightest stars a value of 1 and the dimmers stars a value of 6. Counterintuitively, the more negative the magnitude number, the brighter the object.
The first major accomplishment in exploring the Cosmos came with the invention of the telescope in 1608 in the Netherlands when spectacle (eyeglass) makers Hans Lippershey, Zacharias Janssen, and Jacob Metius, each independently created telescopes.
Early telescopes had primarily terrestrial uses, such as surviving and observing military targets.
Thanks to the invention of the telescope, astronomy began playing a key role in assisting seafarers and travelers more easily navigate throughout the world. The first two government-funded observatories were started in 1667 and 1675, to produce more accurate star charts.
The Italian astronomer Galileo Galilei, who the famous theoretical physicist Albert Einstein called “the father of modern science,” utilized the fledgling technology to further man’s knowledge of the stars.
After learning of the newly invented “spyglass,” a device that made far objects appear closer, Galileo essentially reverse-engineered one and then built his own enhanced version. Galileo, using his newly-built telescope, became the first person to record celestial observations made with the aid of a telescope.
His first discovery was that the Moon was not a smooth sphere as theorized, but he found that the Moon has mountains, craters, and other topographical features, similar to the Earth.
Galileo made another amazing discovery when he observed Jupiter through his telescope. He found 4 stars surrounding the giant planet and later ascertained that these stars were actually moons orbiting Jupiter. He later discovered that the Sun has sunspots. His findings challenged the accepted beliefs of the Catholic Church at the time, especially the pronouncement that the Earth orbits the Sun.
In 1989, a Jupiter-bound space probe was launched bearing his name. During its 14-year voyage, the Galileo space probe and its detachable mini-probe, visited Venus, the asteroid Gaspra, and observed the impact of Comet Shoemaker-Levy 9 on Jupiter and its moons.
In the 19th century, photography aided in mapping out the heavens and consequently, the stellar position catalogs which contained only a few thousand stars soon the number of stars classified in them swelled to tens of thousand. The first celestial objects to be photographed and published were the Moon and Sun, followed by the star, Vega.
The discovery of spectroscopy, which is the study of the absorption and emission of light and other radiation by matter according to its chemical composition, revolutionized astronomy. Astronomers could now determine the chemical makeup of celestial objects, not just their positions.
In the early 20th century, telescope technologies vastly improved, thus causing astronomers to question whether the Milky Way was the entire universe or only one of many distinct galaxies scattered across the universe.
American astronomer Edwin Hubble (the namesake of the Hubble Telescope) answered this question in the 1920s when he was able to distinguish individual stars in the Andromeda Nebula, known today as the Andromeda Galaxy. Hubble concluded that the Andromeda Nebula was actually a separate galaxy, just like our Milky Way.
Other “nebulas” were soon found to be galaxies. Astronomers soon realized that these nebulae were speeding away from Earth. This discovery led to the postulation that the universe was expanding since the time of a giant explosion that had created it eons ago, thus giving birth to the Big Bang Theory.
With the advent of the launch of Sputnik in 1957, astronomy entered the realm of space-based observation. NASA built several space telescopes, but the quantum leap in technology came with the launching of the Hubble Telescope in 1990. Since then an even more advanced and vastly improved space-based telescope, the James Webb Telescope, was launched on Christmas Day, 2021. The James Webb Telescope has sent back unbelievable pictures of the cosmos, deepening our understanding of the nature of the Universe.
The field of professional astronomy split into observational and theoretical branches during the 2oth Century. Observational astronomy is centered around acquiring data from observations of celestial objects, which is then analyzed. Theoretical astronomy is focused on the development of analytical models using computers, to describe celestial phenomena and objects.
There are several subsets to astronomy, such as:
Astrophysics, which applies the laws and theories of physics to astronomical observations. It is an effort to understand how the universe was created and its future evolution.
Astrochemistry, which is the study of the composition and reactions of the building blocks of the universe.
Astrobiology, which is an emerging and, at the moment, primarily theoretical field of astronomy, is the study of life out in space.
Cosmology is sometimes used synonymously with astronomy. However, technically, cosmology is the science of the origin and nature of the universe. The primary postulation in cosmology is the Big Bang Theory, which, at the moment, is the most widely accepted explanation of how the universe began. Cosmology also includes purely theoretical aspects of astronomy, including string theory, dark matter and dark energy, and the concept of multiple universes.
In order to see the bigger picture, astronomers study various wavelengths of the electromagnetic spectrum which comprises radio, microwave, infrared and visible light, ultraviolet, X-rays, and gamma rays.
Optical astronomy uses telescopes that observe visible light. Infrared light can be detected outside the Earth’s atmosphere, and are observed by space-based observatories like the Hubble Space Telescope and the James Webb Space Telescope. Radio astronomy searches for emissions of radio frequencies in the universe, using radio telescopes to detect and amplify radio waves from space.
The difference between astrology and astronomy
Astronomy and astrology have the same origins. Ancient civilizations believed that the sky controlled their lives and that by observation of the motions of celestial bodies, they could know what the future held. During the Renaissance period, rulers used astronomers to advise them on personal decisions based on the positions of the stars and planets.
Thanks to the scientific method, astronomy utilizes data-driven observations to make verifiable predictions relying on state-of-the art technology. Astrology, on the other hand, is now relegated to the realm of new-age superstition, using glass crystals and “simplistic” star charts to predict one’s future.
The zodiac signs, which are the basis of Western Astrology, were identified centuries ago. Due to the irregularity of the Earth’s orbit, the position of the Sun within the signs no longer matches the position of the Sun today. Therefore, while you may have thought you were born under the sign of Virgo, you may actually have been born under Libra.
Astronomy has proven its value to society by spurring technological innovations used in everyday life, giving us a more complete understanding of the Cosmos, and even helping protect humanity from extraterrestrial threats such as asteroids that could trigger an Extinction Level Event.
