Galileo’s Telescope​—Only the Beginning!

WHEN Galileo turned his newly invented telescope to the sky, a whole new vision swam into view. He could see ten times as many stars as any man had ever before seen. The Milky Way now appeared, not as a nebulous mass, but as a kaleidoscope of countless stars, great and small. The moon’s surface was transformed before his eyes from a lustrous porcelain into a mosaic of mountains, craters, and waterless seas.

A few months later, he spotted four of the moons of Jupiter. Then he saw the beautiful rings of Saturn. Directing his telescope to Venus, he noticed certain phases of the planet, subtle changes in illumination and apparent shape. These phases could be explained only if the planet moved around the sun. But if one planet moves around the sun, the others​—including the earth—​must do so also, he concluded. He was right. Thus, in the year 1609, the earth was toppled from its hallowed pedestal as the alleged center of the universe.

But venerated beliefs were not easily abandoned. The Catholic Church ruled that “the view that the earth is not the center of the universe and even has a daily rotation is . . . at least an erroneous belief.” Galileo was hauled before the Inquisition and spent the last years of his life under house arrest. Religious dogmatism, however, could not check the curiosity that the invention of the telescope had raised. The challenge of unlocking the secrets of the universe attracted a growing number of scientists.

Now, after nearly four hundred years of intensive scrutiny, our knowledge of the universe has increased dramatically. Different types of stars, such as red giants, white dwarfs, and pulsars, have been identified. Recently, quasars​—enigmatic objects that emit prodigious amounts of energy—​have been detected in the outer reaches of space. And mysterious black holes​—like unimaginably powerful cosmic whirlpools—​are now believed to lurk unseen in many galaxies.

Powerful optical telescopes enable astronomers to peer far into space and thereby in effect journey billions of years back in time, to the very edge of the visible universe. A vast array of stars and galaxies have been discovered, some so distant that their light is calculated to have taken more than 15 billion years to reach us.a

Although stars in general are weak radio sources, other celestial objects, such as pulsars and quasars, have been discovered thanks principally to radio telescopes. As the name implies, these telescopes detect radio wavelengths rather than optical wavelengths. Since 1961, hundreds of quasars have been detected, many of them in the outer reaches of the known universe.

The task of charting the universe was greater than Galileo could possibly have imagined. Only in this century has man begun to comprehend the enormity of the cosmos, the billions of galaxies of which it is composed, and the staggering distances that separate them.

To help us imagine cosmic distances, physicist Robert Jastrow suggests the following analogy. Imagine the sun scaled down to the size of an orange. Then the earth would be a mere grain of sand circling in orbit around the sun at a distance of 30 feet [9 m]. Jupiter would be like a cherry pit revolving around the orange a city block away, and Pluto would be still another sand grain at a distance of ten city blocks from our imaginary orange, the sun. On that same scale, the sun’s nearest neighbor, the star Alpha Centauri, would be 1,300 miles [2,100 km] away, and the entire Milky Way a loose cluster of oranges separated from one another by about 2,000 miles [3,200 km], with an overall diameter of 20 million miles [30 million km]. Even when everything is scaled down, the figures soon get out of hand.

It is not just the distances that are astounding. As scientists have unveiled the secrets of the universe, peculiar phenomena have come to light. There are neutron stars consisting of matter so dense that a mere teaspoonful weighs as much as 200 million elephants. There are tiny stars called pulsars, one of which winks on and off some 600 times a second. And, of course, there are those tantalizing black holes scientists speculate about. The holes themselves cannot be seen, but their insatiable appetite for light and matter may betray their cryptic presence.

Much, of course, still remains a mystery, shrouded by those immense distances and aeons of time. But what have scientists so far discovered about the universe? Does what they know throw new light on how and why the universe exists?

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[Picture on page 4]

The Jodrell Bank radio telescope, constructed in 1957 in England, was the first fully steerable unit

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Courtesy of Jodrell Bank Radio Telescope

The Universe​—Some Secrets Unlocked

ON THE 4th of July, in the year 1054, Yang Wei Te gazed up at the early morning sky. As official astronomer of China’s Imperial Court, he was meticulously observing the movement of the stars when suddenly a bright light near the constellation of Orion attracted his attention.

A “guest star”​—the name the ancient Chinese gave to such a rare occurrence—​had made its appearance. After dutifully reporting to his emperor, Yang noted that the “guest star” had become so bright that it even outshone Venus and could be seen in broad daylight for several weeks.

Nine hundred years were to pass before this spectacle could be adequately explained. It is now believed that the Chinese astronomer was witnessing a supernova, the cataclysmic death throes of a massive star. The whys and wherefores of such an extraordinary phenomenon are just some of the secrets that astronomy is trying to unlock. The following is one explanation that astronomers have painstakingly pieced together.

Although stars like our sun may have immensely long and stable lives, their formation and demise give rise to the most spectacular sights in the skies. Scientists believe that the life story of a star begins inside a nebula.

Nebula. This is the name given to an interstellar cloud of gas and dust. Nebulas are among the most beautiful objects in the night sky. The one seen on the cover of this magazine is called the Trifid Nebula (or nebula with three clefts). Inside this nebula new stars have been born, which cause the nebula to give off a reddish glow.

Apparently, stars form inside a nebula when the diffuse matter condenses under the force of gravity into contracting regions of gas. These huge balls of gas stabilize when they reach the temperature at which nuclear reactions begin in the core of the cloud, preventing further contraction. Thus a star is born, often in conjunction with others, with which it makes up a star cluster.

Star clusters. In the photograph on page 8, we see a small cluster called the Jewel Box, thought to have been formed just a few million years ago. Its name was coined from the graphic description by 19th-​century astronomer John Herschel: “a casket of variously coloured precious stones.” Our galaxy alone is known to have over a thousand similar clusters.

The star’s energy. A nascent, or developing, star stabilizes as a nuclear furnace is fired in its interior. It starts converting hydrogen to helium by a fusion process somewhat like that which occurs in a hydrogen bomb. Such is the mass of a typical star, like the sun, that it can burn its nuclear fuel for billions of years without exhausting the supply.

But what happens when such a star eventually uses up its hydrogen fuel? The core contracts, and the temperature rises as the star exhausts the hydrogen in the central regions. Meanwhile, the outer layers expand enormously, increasing the star’s radius 50 or more times, and it becomes a red giant.

Red giants. A red giant is a star with a surface temperature that is relatively cool; its color therefore appears red, rather than white or yellow. This phase in a star’s life is relatively short, and it ends​—when most of the helium supply runs out—​with a celestial fireworks display. The star, still burning helium, ejects its outer layers, which form a planetary nebula, glowing because of energy received from its mother star. Eventually, the star contracts dramatically to become a faintly shining white dwarf.

If the original star is massive enough, however, the final outcome is that the star itself explodes. That is a supernova.

Supernovas. A supernova is the explosion that ends the life of a star that was originally much more massive than the sun. Huge amounts of dust and gas are spewed into space by violent shock waves at speeds of over 6,000 miles a second [10,000 km/​sec]. The intense light of the explosion is so bright that it outshines a billion suns, appearing as a sparkling diamond in the sky. The energy liberated in a single supernova explosion corresponds to the total energy the sun would radiate in nine billion years.

Nine hundred years after Yang observed his supernova, astronomers can still see the scattered debris of that explosion, a structure called the Crab Nebula. But something more than the nebula was left behind. At its center they discovered something else​—a tiny object, rotating 33 times a second, called a pulsar.

Pulsars and neutron stars. A pulsar is understood to be a superdense, spinning core of matter left over after a supernova explosion of a star no more than three times as massive as the sun. Having diameters of less than 20 miles [30 km], they are rarely detected by optical telescopes. But they can be identified by radio telescopes, which detect the radio signals that are produced by their rapid rotation. A beam of radio waves rotates with the star, like the beam of a lighthouse, appearing as a pulse to an observer, giving rise to the name pulsar. Pulsars are also called neutron stars because they are principally composed of tightly packed neutrons. This accounts for their incredible density​—over a billion tons per cubic inch [over a hundred million tons per cubic centimeter].

But what would happen if a really massive star went supernova? According to astronomers’ calculations, the core could continue its collapse beyond the neutron-​star stage. Theoretically, the force of gravity compressing the core would be so great that a so-​called black hole would result.

Black holes. These are said to be like gigantic cosmic whirlpools from which nothing can escape. The inward pull of gravity is so strong that both light and matter that get too close are inexorably sucked into them.

No black hole has ever been observed directly​—by definition that is impossible—​although physicists hope to demonstrate the existence of them by the effect they have on neighboring objects. New observing techniques may be needed to unlock this particular secret.

Secrets of the Galaxies

A galaxy is a cosmic structure made up of billions of stars. In 1920 it was discovered that the sun was not the center of our galaxy, as had previously been assumed. Soon afterward, powerful telescopes revealed a host of other galaxies, and man began to comprehend the immensity of the universe.

The misty tapestry we call the Milky Way is really an edge view of our own galaxy. If we could see it from afar, it would look much like a giant pinwheel. Its shape has been likened to two fried eggs placed back to back but, of course, on a far grander scale. Traveling at the speed of light, it would take 100,000 years to cross our galaxy. The sun, situated toward the outer edge of the galaxy, takes 200 million years to complete its orbit around the galactic center.

Galaxies, like stars, still hold many secrets that intrigue the scientific community.

Quasars. In the 1960’s, strong radio signals were picked up from objects far, far beyond our local group of galaxies. They were called quasars​—short for “quasi-​stellar radio sources”—​because of their similarity to stars. But astronomers were perplexed by the prodigious energy quasars emitted. The more luminous one is some ten thousand times as bright as the Milky Way, and the most distant ones detected are over ten billion light-​years away.

After two decades of intensive study, astronomers have come to the conclusion that these distant quasars are very active nuclei of outlying galaxies. But what goes on in the nucleus of these galaxies to generate such enormous energy? Some scientists suggest that the energy is released by gravitational processes rather than by nuclear fusion as in stars. Current theory associates quasars with gigantic black holes. Whether this is correct or not remains uncertain at present.

Quasars and black holes are just two of the puzzles that are yet to be solved. In fact, some of the secrets of the universe may be forever beyond our grasp. Nevertheless, those that have been unlocked can teach us some profound lessons, lessons that have implications far beyond the realm of astronomy.

[Picture on page 7]

Spiral galaxy M83

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Photo: D. F. Malin, courtesy of Anglo-​Australian Telescope Board

[Pictures on page 8]

The Jewel Box

Open star cluster, the Pleiades in Taurus, M45

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Photo: D. F. Malin, courtesy of Anglo-​Australian Telescope Board

[Pictures on page 8]

Orion nebula, with inset showing Horsehead nebula

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Photo: D. F. Malin, courtesy of Anglo-​Australian Telescope Board

Lessons Learned From the Universe

“I don’t pretend to understand the Universe​—it’s a great deal bigger than I am.”​—Thomas Carlyle, 1795-1881.

A HUNDRED years later, we have a better idea of how much bigger than we are the universe really is. Although scientists understand a lot more than they did, their situation is still, as one astronomer described it, like that of “the 18th-​century botanists in the jungle finding all those new flowers.”

Despite our limited knowledge, certain conclusions can be drawn. And these conclusions have to do with the most important questions of all​—how the universe works, and how it got here in the first place.

Order Rather Than Chaos

The study of the nature of the universe is called cosmology. That term is derived from two Greek words, kosmos and logos, indicating ‘the study of order or harmony.’ This is an apt name because order is precisely what astronomers encounter, whether they investigate the motion of celestial bodies or the matter of which the cosmos is composed.

Everything in our universe is in motion, and the movement is neither erratic nor unpredictable. Planets, stars, and galaxies move through space according to precise physical laws, laws that enable scientists to predict certain cosmic phenomena with unerring accuracy. And incredibly, the four fundamental forces that control the tiniest atom also govern the mightiest galaxies.

Order is also manifest in the very stuff of which the universe is built. “Matter is . . . organised on all scales from very small to very large,” explains The Cambridge Atlas of Astronomy. Far from being randomly distributed, matter is structured in an orderly way, whether it is the way electrons are linked to the protons and neutrons of the atomic nucleus or it is the mutual attraction that binds together an enormous cluster of galaxies.

Why does the universe reveal such order and harmony? Why are there transcendent laws ruling it? Since these laws must have existed before the origin of the universe​—otherwise they could not control it—​the logical question is: Where did they come from?

Famous scientist Isaac Newton concluded: “This most beautiful system of the sun, planets, and comets could only proceed from the counsel and dominion of an intelligent and powerful Being.”

Physicist Fred Hoyle said: “The origin of the Universe, like the solution of the Rubik cube, requires an intelligence.” The conclusion that there must be a supernatural Lawgiver is confirmed by our understanding of the origin of the universe.

The Ultimate Question: How Did the Universe Get Here?

Theoretical physicist Hawking explains: “The early universe holds the answer to the ultimate question about the origin of everything we see today, including life.” What exactly is the present scientific view of the early universe?

In the 1960’s, scientists detected faint background radiation coming from all parts of the sky. This radiation was said to be a reverberation coming from the primeval explosion that astronomers have christened the big bang. So enormous was the explosion, they say, that its echo could still be detected billions of years later.a

But if the universe suddenly exploded into existence between 15 billion and 20 billion years ago, as most physicists now believe (though that is hotly contested by others), a crucial question arises. Where did the original energy come from? In other words, what came before the big bang?

This is a question that many astronomers prefer to dodge. One of them confessed: “Science has proved that the world came into being as a result of forces that seem forever beyond the power of scientific description. This bothers science because it clashes with scientific religion​—the religion of cause and effect, the belief that every effect has a cause. Now we find that the biggest effect of all, the birth of the universe, violates this article of faith.”

An Oxford University professor wrote more pointedly: “The first cause of the universe is left for the reader to insert. But our picture is incomplete without him.” The Bible, however, sets matters straight, identifying “the first cause” by saying: “In the beginning God created the heavens and the earth.”​—Genesis 1:1.

Man’s Insignificance

The simplest lesson the universe teaches us is the most obvious one, one that proud medieval man strove to ignore but one that Biblical poets humbly acknowledged millenniums ago​—that of man’s insignificance.

Recent discoveries reinforce King David’s realistic appraisal: “When I see your heavens, the works of your fingers, the moon and the stars that you have prepared, what is mortal man that you keep him in mind, and the son of earthling man that you take care of him?”​—Psalm 8:3, 4.

Astronomy has unveiled the immensity and the majesty of the cosmos​—the stars of Gargantuan proportions, the distances beyond imagination, the aeons of time that defy comprehension, the cosmic furnaces that generate temperatures of millions of degrees, the eruptions of energy that dwarf a billion nuclear bombs. Yet, all of this is well described in the book of Job: “Look! These are the fringes of his ways, and what a whisper of a matter has been heard of him! But of his mighty thunder who can show an understanding?” (Job 26:14) The more we learn about the universe, the scantier our knowledge appears, and the smaller our own place in it becomes. For the objective observer, it is a sobering lesson.

Isaac Newton admitted: “I seem to have been only like a boy playing on the seashore, and diverting myself in now and then finding a smoother pebble or a prettier shell than ordinary, while the great ocean of truth lay all undiscovered before me.”

The humility that such comprehension should stir in us will help us to acknowledge that there is One who created the universe, One who established the laws that govern it, One who is far greater and wiser than we are. As the book of Job reminds us: “With him there are wisdom and mightiness; he has counsel and understanding.” (Job 12:13) And that is the most important lesson of all.

As more secrets of the universe are unlocked, even greater mysteries are uncovered. A future article will discuss some of the latest discoveries that are now puzzling astronomers and raising new questions that are fueling debates among cosmologists.

[Footnotes]

[Picture on page 10]

Apparatus for detecting background radiation from the theoretical big bang

[Credit Line]

Courtesy of the Royal Greenwich Observatory and the Canary Islands Institute of Astrophysics