Time machines: telescopes on earth and in space

Exploring iconic telescopes from Galileo to the James Webb and from radio to gamma rays. Photo: Hubble close-up. Image credit: NASA


UNITED KINGDOM,  October 17, 2013 — This article carries a public health warning: Astronomy is addictive! It all starts innocently enough, gazing at the Moon, making a wish on a shooting star. Before you know it you are standing in the freezing cold and pitch dark at 4 in the morning, your numb fingers fiddling with eyepieces and control knobs on a telescope that has cost you a small fortune in a bid to hunt down some obscure deep sky object while you curse every security light and street lamp in the area.

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Hans Lippershey is generally credited with patenting the first practical telescope “for seeing things far away as if they were nearby” in 1608. His telescope could only manage 3x magnification but along came Galileo the following year who improved and perfected the technology to magnify up to 33 times and used it to discover four satellites of Jupiter. Here is a potted history of the telescope.

A few words of advice for any fledgling astronomers. Don’t rush out and spend a pile of money on the biggest, all singing, all dancing telescope that money can buy, not yet, that comes later.

First just go out at night and look up. Get to know your night sky. How much light pollution do you have to contend with? Which direction is your clearest view, uncluttered by trees or buildings. All is not lost if conditions are less than ideal. You soon learn to make the most of what you’ve got. My own garden is surrounded by trees leaving me a narrow south facing band of clear sky down, almost to the horizon.

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Arm yourself with a good, readable and user friendly astronomy book. There are also lots of free planetarium software available for your computer, tablet or smartfone.

Now for some naked astronomy. You can keep your clothes on if you wish but no equipment other than your eyes is needed. Just get to know the Moon first. Try to catch it about the same time each night and notice how its position and phase changes over time. Pick out the main features with a moon map.

Next come a few of the main constellations. The Big Dipper in Ursa Major, the three stars that make up the belt in Orion and the “W” of Cassiopiea are great starting places and can be used to point the way to other less recognisable constellations or the positions of planets as they wander through the sky. Slowly learn your way around the sky, hopping from one marker to the next.

Join your local astronomy club. You will get loads of practical and friendly advice from people who know, and be able to get your hands on a wide variety of telescopes.

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The first equipment to buy is a good pair of binoculars. There are lots of binocular objects to keep you interested before taking the plunge and buying your first scope, by which time I hope you will be hooked! There are a plethora of amateur telescopes available to buy, from simple and small to large and complex. Here are the folks at BBC’s Sky at Night with some handy tips to guide you.

And then there are the really big professional telescopes. These can be loosely grouped according to the wavelength of electromagnetic radiation they are designed to collect. The most accessible are the optical telescopes. The largest of which is the W. M. Keck Observatory, a pair of 10 meter (32.8 feet) diameter telescopes near the summit of Mauna Kea in Hawaii. The two can be operated together as an interferometer to give higher resolution.

We then move on to radio astronomy. It was Karl Jansky who made the initial detection of radio waves from an astronomical object in the 1930s. The Very Large Array based in New Mexico is named after him. The 27 independent antennae that make up the array each has a dish diameter of 25 meters (82 feet) When used together these give a maximum baseline of 36km (22miles) Most notably featured in every good geek’s favorite movie “Contact”, based on the book by Carl Sagan, it is fitting that this video is narrated by the movie’s star Jodie Foster.

Earth’s atmosphere protects us from most of the X-rays from space so space-based telescopes are needed to make observations in these wavelengths. NASA’s Chandra X-ray Observatory was launched in 1999 and is sensitive to X-ray sources 100 times fainter than any previous X-ray telescope.

The Fermi Gamma-ray Space Telescope has just celebrated five years of observing the most energetic form of electromagnetic radiation to study pulsars, dark matter and gamma ray bursts, the brightest electromagnetic events in the universe.

No study of telescopes could miss out the greatest of them all. The Hubble Space Telescope launched in 1990, has perhaps done more than any other mission to bring the wonder and beauty of space to the world. After an unpromising start when an infinitessimal fault in the primary mirror meant the images were not as sharp as expected Hubble was fitted with what amounted to a pair of glasses. Since then the telescope has gone on to produce some of the most stunning images ever returned from space and has arguably done more than any other mission to advance our knowledge of the universe.

Where to next? If all goes to plan (keeping everything crossed) in five years time The James Webb Space Telescope (JWST) will be ready to launch. It is expected to have unprecedented resolution and sensitivity from long-wavelength visible to the mid-infrared and be able to study the formation of stars and planets and the birth and evolution of galaxies. Wherever you are, go out and enjoy the night sky. Astronomy is looking up!

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Jenny Winder

Jenny Winder is a British science writer for SEN - the Space Exploration Network,  specialising in astronomy, physics and space exploration.

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