The telescope stands as a timeless symbol of human curiosity and ingenuity, allowing us to peer into the depths of the cosmos and unravel its mysteries. From the humble beginnings of the first optical telescopes to the cutting-edge technology of space-based observatories, the evolution of telescopes has been a testament to humanity's relentless pursuit of knowledge about the universe.
Terry Bailey explains.
A 17th century depiction of a Dutch telescope.
The story of the telescope began in the early 17th century, with the Dutch spectacle maker Hans Lipperhey often credited as its inventor. Lippershey's simple yet revolutionary design consisted of a convex objective lens and a concave eyepiece, which allowed for distant objects to be magnified. This basic principle laid the foundation for the development of optical telescopes.
One of the most notable figures in the early history of telescopes is Galileo Galilei, who improved upon Lipperhey's design and used his telescope to make groundbreaking astronomical observations. In 1609, Galileo observed the Moon’s surface, in addition to the first 4 moons of Jupiter, as well as the phases of Venus, forever altering our understanding of the cosmos and challenging the prevailing geocentric model of the universe.
Throughout the centuries, optical telescopes continued to evolve, with advancements in lens and mirror technology leading to increasingly powerful instruments. In the 17th and 18th centuries, astronomers such as Johannes Kepler and Isaac Newton made significant contributions to telescope design, developing the reflecting telescope, which used curved mirrors instead of lenses to gather and focus light.
By the 19th century, the construction of large refracting telescopes with massive lenses became feasible, allowing astronomers to explore the universe with unprecedented clarity. The construction of the Yerkes Observatory's 40-inch refractor in 1897 marked a milestone in telescope engineering and remained the largest refracting telescope in the world for decades.
20th century
While optical telescopes provided valuable insight into the visible universe, astronomers soon realized that much of the cosmos remained hidden from view. In the early 20th century, the discovery of cosmic radio waves by Karl Jansky paved the way for the development of radio telescopes, which could detect radio emissions from celestial objects.
One of the earliest radio telescopes was built by Grote Reber in 1937, consisting of a large parabolic dish that focused radio waves onto a receiver. Radio telescopes opened a whole new window into the universe, allowing astronomers to study phenomena such as pulsars, quasars, and the cosmic microwave background radiation, (CMBR).
In the mid-20th century, the discovery of X-rays from celestial sources prompted the development of X-ray telescopes. Unlike optical telescopes, which use lenses or mirrors to focus light, X-ray telescopes must employ grazing-incidence mirrors to reflect and focus X-rays onto detectors. The launch of the Uhuru satellite in 1970 marked the first dedicated X-ray observatory in space, revolutionizing our understanding of high-energy phenomena such as black holes and supernovae and remnants.
While ground-based telescopes provided valuable observations, they were limited by atmospheric distortion and light pollution. The advent of space orbiting telescopes promised to overcome these limitations by placing observatories above Earth's atmosphere, allowing for clearer and more detailed observations of the cosmos.
One of the most iconic space telescopes is the Hubble Space Telescope (HST), launched by NASA in 1990. Equipped with a 2.4-meter primary mirror and an array of scientific instruments, Hubble has captured breathtaking images of distant galaxies, nebulae, and other celestial phenomena. Its observations have led to numerous discoveries, including the expansion rate of the universe and the existence of dark energy.
In 1999, NASA launched the Chandra X-ray Observatory, the most powerful X-ray telescope ever built. Orbiting high above the Earth, Chandra has provided unprecedented views of X-ray sources such as black holes, supernovae and galaxy clusters, shedding light on the violent processes that occur throughout in the universe.
Recent years
As technology continues to advance, astronomers are already planning the next generation of telescopes that will push the boundaries of our understanding of the cosmos. One such project is the James Webb Space Telescope (JWST), which was launched in 2022. With its massive segmented mirror and advanced infrared instruments, JWST is able to peer deeper into space than ever before, probing the early universe and studying the formation of stars and galaxies.
Another groundbreaking project is the Square Kilometer Array (SKA), a next-generation radio telescope that will consist of thousands of antennas spread across a vast area. Scheduled for completion in the late 2020s, SKA will be the largest and most sensitive radio telescope ever built, allowing astronomers to explore the universe with unprecedented precision and detail.
In addition to these flagship projects, numerous ground-based and space-based observatories are in development, each poised to expand our knowledge of the cosmos in the instruments unique way based upon the device’s design specifications. From the search for habitable exoplanets to the study of dark matter and dark energy, the future of astrophysics / astronomy is filled with promise and discovery.
The history of the telescope is a true testament to humanity's insatiable curiosity and relentless pursuit of knowledge about the universe. From the humble beginnings of the first optical telescopes to the sophisticated instruments of today, telescopes have revolutionized our understanding of the cosmos and reshaped our place in the universe.
As we look to the future, the next generation of telescopes promises to unlock even more secrets of the universe, from the nature of dark matter and dark energy to the search for extraterrestrial life forms. With each new technological advancement, we move closer to unraveling the mysteries of the cosmos and gaining a deeper understanding of our place in the vastness of space.
Find that piece of interest? If so, join us for free by clicking here.
Special notes
It is important to understand that based upon the speed of light and the vast distances to celestial object observed by telescopes, across all wave lengths of the light spectrum, that by the time the light reaches an observer, these observations are already in the past.
For example if an observer looks at the nearest galaxy, (M31j, to our own, galaxy, which is 2.5 million light years away, then the light from the Andromeda galaxy, (M31), has already taken 2.5 million years to reach Earth, thus the image observed in a telescope is already 2.5 million years old.
The Electromagnetic light spectrum, includes Gamma γ-rays, x-rays, ultraviolet, visible light, infrared, microwaves and radio waves.
The speed of light is 299,792,458 meters per second, which is approximately 300,000 kilometers per second.
One light year is the equivalent to 9.46 trillion kilometers.
Point of interest
The current count of moons officially recognized orbiting the planet Jupiter is 95.
