Today’s reflecting telescopes use immense, bowl-shaped mirrors (up to 236 inches [600 cm] across!) to collect light from faraway heavenly bodies. They are thus able to detect objects ten million times fainter than those that can be seen with the naked eye. Why, it is claimed that one telescope in Australia could detect a candle flame a thousand miles (1,600 km) away!

Interestingly, though, astronomers today still run into the same problem Galileo faced. He noticed that when magnified the stars increased in number but not in size. Galileo reckoned that the stars must be incredibly distant to remain mere points of light under magnification. Though today’s astronomers seemingly know just how far away these celestial objects are, they still, even with their precision lenses and polished mirrors, see stars as pinpricks of light. As The Observer’s Book of Astronomy declares: “The stars are so remote that no telescope yet built will show them as anything except points of light.”

This, though, does not stop scientists from trying to get a closer look at the stars. For example, in 1986, the National Aeronautics and Space Administration (U.S.A.) plans to launch a large space telescope that will orbit above the earth’s atmosphere. Scientists believe it will detect objects 50 times fainter than earthbound telescopes can detect.

Fortunately, there are other ways to see the universe. Some time ago it was discovered that certain heavenly bodies emit radio waves. By the time these signals reach earth they can be fainter than one trillionth of a watt. Hence, large radio telescopes have been developed to pull in and amplify these signals. In this way astronomers have been able to see quasars, pulsars and other intriguing phenomena.

Astronomers, therefore, no longer spend hours squinting through a telescope’s eyepiece, as did Galileo. The Encyclopædia Britannica explains: “Almost all astronomical research is done photographically or photoelectrically, rather than visually . . . Objects can be photographed that are many times fainter than can be seen by looking through the eyepiece. One photographic plate may contain a vast amount of information . . . 1,000,000 star images and 100,000 galaxian images on it.”

Scientists can do remarkable things with such photographs. The magazine Sky and Telescope once explained that a technique called speckle interferometry can reveal the disks of some red supergiants, though the rest of the stars​—even the closest ones—​remain mere points of light.

The closest star to our sun, as seen by the naked eye, turns out to be three when viewed through a telescope. One is Proxima Centauri. The other two are a pair of stars that revolve around each other every 80 years and are known as Alpha Centauri. Except for the sun, these three are the nearest of all the stars, and yet they are 4.3 light-years (over 25 trillion miles; 40 trillion kilometers) from earth! Observes the book Astronomy: “If the size of the sun is represented by one of the periods on this page, the sun’s nearest neighbor among the stars, the double star Alpha Centauri, would be shown on this scale by two dots 16 kilometers [9.6 mi] away.”

Crossing the south celestial pole are what appear to be two patches of cloud. In the 15th century, Portuguese navigators called them Clouds of the Cape. Later they were named after the famous explorer Ferdinand Magellan. Telescopes reveal that both are vast external galaxies. The Large Magellanic Cloud alone contains an estimated five thousand million stars.

[Blurb on page 4]

An estimated 200 globular clusters are in our Milky Way galaxy, each with thousands to hundreds of thousands of stars

[Picture on page 5]

Telescopes have revealed a universe filled with billions of galaxies, each with billions of stars