Telescope Facts
Telescope Facts

42 Illuminating Telescope Facts

Karin Lehnardt
By Karin Lehnardt, Senior Writer
Published March 27, 2017
  • Telescopes not only help magnify far-away objects but they also allow humans to “see” parts of the light spectrum beyond visible light, including gamma rays, X-rays, ultraviolet rays, infrared rays, microwaves, and radio waves.[3]
  • Galileo did not invent the telescope; he was, however, the first to methodically use it to peer into the night sky. Dutch eyeglass maker Hans Lippershey (1570–1619) actually invented the optical telescope (telescopes that see visible light) in 1608.[7]
  • Telescopes perform three main functions: light gathering, resolving, and magnifying.[14]
  • The single most important factor in determining how well a telescope will perform is aperture, or the diameter of a telescope’s lens or mirror. Its aperture determines the brightness and sharpness of its images.[8]
  • The world’s most expensive telescope is the Hubble Space Telescope (HST) at $2.1 billion. Its replacement, the Webb telescope, due to launch in 2018, is estimated to cost $8.3 billion.[1]
  • JWST Telescope Fact
    The JWST telescope will allow astronomers to look much closer to the beginning of time
  • The successor to the Hubble Space Telescope is the James Webb Space Telescope, which is scheduled to be launched in 2018. It will observe in infrared and will have a 21.3-foot (6.5-meter) mirror, which will allow for extremely high resolution to cosmic images.[10]
  • There are three basic telescope designs: refractor, reflector, and catadioptric. A refractor telescope has a big lens at the front to collect and concentrate light. A reflector telescope uses a mirror to do this. Most small telescopes are refractor telescopes. Almost all large telescopes are reflectors. Catadioptric telescopes are a combination of mirrors and lenses and are the most modern design.[8]
  • Before the invention of the telescope, early astronomers used many different kinds of instruments to study the stars, including the astrolabe, the quadrant, and the armillary sphere.[14]
  • Merchants and the military eagerly bought early telescopes. The used them to see approaching ships to try to beat competitors.[6]
  • Most modern astronomers operate telescopes remotely with computers and rarely look through a telescope’s eyepiece.[6]
  • The word “telescope” is from the Greek tele, meaning “far,” and skopein, meaning “to look or see.” It was coined in 1611 by the Greek mathematician Giovanni Demisiani for one of Galileo’s instruments. Galileo had initially used the term “perspicillum.”[3]
  • If I had a time machine, I'd visit Marilyn Monroe in her prime or drop in on Galileo as he turned his telescope to the heavens.

    - Stephen Hawking

  • The Hubble Space Telescope was launched in 1990. It was seven years late and over budget, but it has become the source of roughly 25% of all published astronomy papers.[6]
  • Telescopes can see about 13 billion light-years away, which scientists believe is the age of the universe. Looking out that far is akin to looking back in time.[14]
  • The Hubble Space Telescope is the most productive scientific instrument ever constructed. It is about the same size as a school bus and, on Earth, it weighs over 11 tons.[14]
  • The Hubble Space Telescope was revolutionary not only because it helped astronomers refine the age of the universe but it also helped scientists discover dark energy, a mysterious force that is speeding up the expansion of the universe.[8]
  • Aiming the Hubble Space Telescope at distant targets is akin to holding a laser light steady on dime that is 200 miles away.[13]
  • On March 10, 2013, 526 people gathered at the South by Southwest (SXSW) festival presentation on astronomy and NASA’s James Webb Space Telescope, which set a new Guinness World Record for the biggest astronomy lecture ever.[10]
  • Interesting VLA Fact
    The VLA site is open to visitors year round during daylight hours
  • The Very Large Array (VLA) has appeared in American pop culture several times, including the movies Contact (1997) and Terminator Salvation (2009).[2]
  • The European Extremely Large Telescope (E-ELT) will barely beat out Hawaii’s Thirty Meter Telescope as the world’s largest (and least creatively named) telescope once it’s completed in 2024. It will feature a 128-foot (39-meter) light-collecting surface and will be built atop Cerro Armazones in Chile’s Atacama Desert. It is expected to cost $1.4 billion.[9][11]
  • The Atacama Large Millimeter/submillimeter Array (ALMA) is the world’s largest interferometer telescope (an array of telescopes working in tandem) in the world. It has captured images of the most distant observations of water to date.[1]
  • The Very Large Telescope at the Paranal Observatory in Chile is a 27-foot (8.2-meter) interferometer. It as the first telescope to capture an image of an extrasolar planet. It also captured the afterglow of the farthest gamma ray burst astronomers have ever found.[1]
  • There are 13 telescopes on the slopes of Mauna Kea, a sacred site to the indigenous Hawaiian people. In 2015, Hawaiian Governor David Y. Ige sparked controversy when he announced that yet another telescope, the 18-story Thirty Meter Telescope (TMT), would also be constructed on the mountain. Its first light is expected in the 2020s.[5]
  • The world’s largest infrared space telescope is Herschel, which has an 11.5-foot (3.5-meter) primary mirror. Launched in 2009, it has observed star formation in galaxy clusters, identified a molecule required for making water in expiring stars like the sun, and conducted a large-scale cosmic dust survey.[1]
  • An “Extremely Large Telescope” (ELT) is the name of a type of telescope. Existing or soon-to-be-built ELTs include 1) the European Extremely Large Telescope (E-ELT), 2) the Thirty Meter Telescope (TMT), 3) the Giant Magellan Telescope (GMT), the Large Binocular Telescope (LBT), and the Gran Telescopio Canarias (GTC).[1]
  • Interesting Hubble Telescope Facts
    The Hubble telescope has produced more than 45 terabytes of data, enough to fill over 5,800 DVD movies
  • Since the Hubble Space Telescope began operating in 1990, it has traveled over 3 billion miles and made over 1.2 million observations. It orbits 340 miles above Earth at 17,900 mph. If a car moved that fast, it would take 10 minutes for it to travel from coast to coast in the USA.[6]
  • The first published scientific work based on telescope observations is Galileo’s Sidereus Nuncius, or the “Starry Messenger,” in 1610. It details Galileo’s observations of the moon, hundreds of previously unobserved stars, and the Medicean stars (or moons) of Jupiter. It also contains more than 70 drawings and diagrams of the moon and constellations.[13]
  • In 1637, Rene Descartes noted of the telescope: “By taking our sense of sight far beyond the realm of our forebears’ imagination, these wonderful instruments, the telescopes, open the way to a deeper and more perfect understanding of nature.”[13]
  • The telescope was one of the central instruments of the Industrial Revolution.[8]
  • The telescope revolutionized not only science but also philosophy. Specifically, it helped shift authority in the observance of nature from people to instruments. It also revolutionized such questions as the origin of humans, their place in the universe, their relationship to religion, and the trajectory of their future.[8]
  • The Catholic Church has had a historical interest in astronomy due to the astronomical basis of the calendar by which Holy Days and Easter are set. The Church even has its own telescope, which is housed in the Vatican Observatory in Italy. It also operates a telescope at the Mount Graham International Observatory in the United States.[4]
  • While lenses were known since the time of the ancient Greeks and Islamic scholars, they were not introduced to Europe until the 13th century. For reasons unknown, telescopes were not invented until the 17th century.[8]
  • The Hubble Space Telescope has taken thousands of pictures, but probably the most famous image is called the “Pillars of Creation.” The pillars are vast clouds of gas and dust in the distant Eagle Nebula.[14]
  • Interesting Pillars of Creation Fact
    The Pillars of Creation are 6,500 light-years away

  • Just as important as a telescope’s mirror or lens is the way a telescope is mounted. John Hadley (1682–1744) invented what is now called an altitude-azimuth mount, which allows an astronomer to track the movement of objects along two axes.[13]
  • In 2015, NASA’s Kepler telescope found the most Earth-like planet ever discovered. Coined “Earth 2.0,” this potentially water-yielding planet is 1,400 light years away from our Earth 1.0.[12]
  • The world’s biggest radio telescope dish is located in a jungle hollow at Arecibo, on the island of Puerto Rico. The dish is 1,000 feet across. Radio telescopes are so large because there is not as much information in a radio signal as in a light beam.[13]
  • An ultraviolet telescope is used to study objects in space that emit ultraviolet (UV) light, such as the sun and newly formed stars. Because Earth’s ozone layer blocks most UV rays that reach earth, most UV telescopes are mounted to space satellites.[13]
  • The phrase “First Light” refers to the moment when a new telescope is trained on the sky for the first time.[13]
  • The Hubble Space Telescope can observe objects in space in visible, ultraviolet, and infrared light. Astronomers at NASA control Hubble with radio commands from the ground.[14]
  • Interesting Galileo Fact
    Galileo did not invent the first telescope, but he made many groundbreaking discoveries with it
  • With the help of his telescope, Galileo discovered Jupiter’s satellites and the craters on Earth’s moon. He also used his telescope to look at the sun, which may have led to his blindness later in life.[6]
  • The only two planets in the solar system that the Hubble Space Telescope has not photographed are Earth and Mercury. Hubble is too close to Earth to take a clear picture, and Mercury is so close to the sun that the planet’s intense reflected light would damage Hubble’s instruments.[14]
  • Infrared telescopes create images from infrared waves, which are also known as heat waves. All objects emit infrared waves, though warmer objects give off more infrared rays than colder ones. Most infrared telescopes on Earth are reflectors with a bowl-shaped mirror. They are also typically built high on mountains because gases in the atmosphere block infrared rays.[13]
  • One of the largest telescopes in the world—located on Mt. Graham, Arizona—is like a giant pair of binoculars. Appropriately called the Large Binocular Telescope, it consists of two side-by-side telescopes, each 28 feet (8.4 meters) across.[3]

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