AURA Gemini South Telescope in Chile

The TELESCOPE is 400 years old.

Hans Lippershey, also known as Jan or Hans Lippersheim, was a maker of eyeglasses, or spectacles, in the Netherlands, when he invented the "looker" in 1608.

Not all historians agree that Lippershey was the first to build a telescope, but one story tells of two children playing with lenses in his shop. They told him a weather vane on a church seemed larger when peered at through two lenses. He placed a tube between the lenses, and made what today we call a telescope.

Kijker. When Lippershey announced his invention on October 2, 1608, he called it a kijker, which means looker in Dutch.

Whether or not his looker was the first, Lippershey seems to have been the first person to describe a telescope in writing. That alone became important when the news reached Italian stargazer Galileo Galilei, who then built his own telescope and used it to revolutionize the study of extraterrestrial bodies.

Transformation. Lippershey's looker changed everything for astronomers who previously had lacked reliable tools to observe faraway stars or even the planets in our Solar System.

Before Lippershey and Galileo, magnification instruments had not been used to investigate objects beyond Earth. Since their time, far more powerful visible-light telescopes have been developed along with other types of telescopes capable of "seeing" invisible forms of radiation, such as infrared, ultraviolet, radio, X-ray, and gamma-ray.

Optical telescopes 400 years later, as represented by the Hubble Space Telescope, are 100 million times more sensitive than Galileo's telescope.

Even so, while today's visible-light telescopes are far more powerful and adaptable, the underlying blueprint has remained the same since 1608.

What is a telescope? A telescope is a device used by an astronomer to magnify images of distant objects. It makes faraway things seem nearby.

A telescope extends human vision by making distant things appear larger, sharper and brighter. Some telescopes can be used to record images of objects not seen by the human eye.

Telescopes have been improved by later inventions – the camera, computer, spectrograph, charge-coupled device, rocket, and satellite.

Telescopes as tools. Telescopes are the main tools used by amateur and professional astronomers to explore the Universe. The way a telescope works depends on what an astronomer wants to look for across deep space.

simple diagram of the electromagnetic spectrum
For most people, a telescope is an optical device, which lets an astronomer see objects in space that radiate or reflect visible light. However, much of what can be seen across the Universe is invisible to human eyes because we see only the visible light portion of the electromagnetic spectrum.

Seeing other wavelengths. While the first optical telescope was created 400 years ago, the other kinds of telescopes were invented in the 20th century.

Since the 1960s, telescopes sent up to orbit Earth have allowed astronomers to observe a wider portion of the electromagnetic spectrum.

Stars, black holes, pulsars, quasars, galaxies and other objects strewn across deep space emit lots of energy across the electromagnetic spectrum. Astronomers use radio, infrared, ultraviolet, X-ray and gamma-ray telescopes to look at those invisible emissions to gain a better understanding of the Universe.

Types of Astronomy

Each kind of astronomy needs its own telescope to tune in a different wavelength of energy along the electromagnetic spectrum. Many celestial phenomena can be seen at more than one wavelength.

The Next Generation

There are scores of large telescopes already based on Earth. However, even-larger telescopes on Earth are planned and under construction at such disparate locations as Arizona, British Columbia, California, Canary Islands, Chile, China, Greece, Hawaii, Ireland, South Africa and Wisconsin.
PLANNED TELESCOPES ON EARTH »» There's a lot to see at all wavelengths and, so far, much of it remains to be explored. Telescopes positioned on the surface of Earth are unable to observe many portions of the spectrum because much of the energy coming to us from across the Universe is blocked by our planet's outer atmosphere or else absorbed by moisture in the atmosphere before it can reach the ground. To overcome that problem, telescopes are based in space.

Dozens of telescopes also have been launched to space in recent decades. Many more are planned with names such as Agile, ARISE, COBRAS, Constellation X, Darwin, EXIST, ExNPS, GAIA, Generation-X, Herschel, HSIM, IRIS, Kepler, LISA, MAXIM, Pathfinder, Planck, RadioAstron, SAMBA, SIM, Spectrum, StarLight, Swift, SXG, TPF and Webb.

Seeing History

Staring into Earth's night sky is looking at a Universal history book

It's a history book that covers all the way back to the very beginning of time.

Each star in the sky is a chapter in the book. You are not really seeing the star as it is now. You are looking at the star as it used to be when the light we see now left it long ago.

The deeper we look into space, the farther back in time we are seeing.

Light from the galaxies farthest away is billions of years old.

For instance, astronomers recently used the Keck Telescope in Hawaii to see a cluster of galaxies 11.4 billion lightyears from Earth.

The astronomers said the light had been traveling for 11.4 billion years to get to Earth. Therefore, they said the distance was 11.4 billion lightyears.

The lightyear is a measure of distance equivalent to about:
• 5.9 trillion miles
• 9.5 trillion km
• 63,241 astronomical units
• 0.3066 parsecs

When you see something that is billions of lightyears away from us, you are looking back billions of years in time. You are seeing what happened back then.
The expanse of wavelengths across the full electromagnetic spectrum is considerably wider than the narrow rainbow of colors seen by the human eye. Astronomers need telescopes that can receive the entire range of frequencies so they can observe the Universe of objects radiating energy across the extent of the spectrum.

For instance, much of the Universe consists of gas and dust that is far too cold to radiate in visible light or at shorter wavelengths such as X-rays. However, even at temperatures far below the most frigid spot on Earth, the gas and dust in deep space can release energy at far-infrared and submillimeter wavelengths. Sometimes stars and other bodies are hot enough to shine at optical wavelengths that we might be able to see, but they are hidden from our view behind enormous clouds of dust that absorb the visible light. Fortunately, the dust clouds re-radiate the absorbed energy at the far-infrared and submillimeter wavelengths. High energy astrophysics is a young discipline, whose history is only a few decades old, and requires space-borne instruments to observe the X-ray and gamma-ray sky.

Learn More About Telescopes

Gold Deep Space BulletNASA's Great Observatories
               Hubble   Compton   Chandra   SIRTF

Gold DingbatGemini South Telescope Twin in Chile

Gold DingbatJames Webb Space Telescope

Gold DingbatLovell Telescope at Jodrell Bank Observatory

Gold DingbatUlug'bek's Great Observatory at Samarkand

Gold DingbatHubble Is Not Alone Up There
  Gold DingbatLightyears

Gold DingbatThe Nassau Astronomical Station

Gold DingbatRemote Control Telescope on the Internet

Gold DingbatThe Puckett Private Observatory

Gold DingbatNASA's Deep Space Network

Gold DingbatThe Beauty of Hubble


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