Astronomy Becomes a Science

Astronomy Becomes a Science

After 323 B.C., the year of the death of Alexander the Great, the Centre of Greek learning shifted from Athens to Alexandria. Another change, and a healthy one, was the appearance of a group of men who felt that theory had too greatly out stripped observation. Astronomy depends to a larger extent on the detailed and systematic observation of the movements of the heavenly bodies, a point which earlier Greeks had tended to overlook.

Foremost in the new approach was Aristarchus of Samos, who about 260 B.C. attempted to determine the sizes and distances of the sun and the moon. He also anticipated Copernicus by suggesting that the sun and celestial sphere were at rest while the planets, the earth included, revolved around the sun. But since his scheme was far removed from the earth-centered of commonsense view, it received little or no support.

The Evening Skies. Photo: Elena

The practical approach was also favored by Eratosthenes, a younger contemporary of Aristarchus and head of the great library at Alexandria. He was the first to measure the diameter of the earth by a sound method based on observation of the sun`s height in the sky, and his result, 7,850 miles, was only 50 miles short of the actual diameter.

About 150 B.C. in Alexandria, the Greek astronomer Hipparchus used measuring instruments to determine the places of objects in the sky with an accuracy greater than ever previously obtained. Altogether he recorded the positions of 1,080 stars and grouped them into six magnitudes according to their brightness. By comparing his own observations with others made about 150 years earlier he discovered the precession of the equinoxes, although in this he was preceded by Kiddinu, a Babylonian astronomer.

Scientia. Photo by Elena

Early Ideas and Discoveries in Astronomy

Early Ideas and Discoveries in Astronomy

Astronomy, probably the oldest of the sciences, has origins lost in the mists or prehistory. One likely source was the land of the two rivers Tigers and Euphrates, a country we now call Iraq. There, Sumerian priests some 6,000 years ago worshiped the Sun, Moon, and “the whole host of heaven,”, and watched the sky for signs of the progress of time.

Natural Intervals of Time

In early time, no less than today, the daily course of the sun provided a natural and obvious measure of time. The Sun’s regular appearance of day and night, and its progress across the sky, associated with corresponding changes in the lengths and directions of shadows, led to the introduction of the hour. From the Sun’s motion relative to the stars came the year and the establishment of the seasons and times of seedtime and harvest. From the regular cycle of the waxing and waning of the Moon was derived the month, the basic unit of Sumerian and Babylonian calendars.

Difficulties arose when early people tried to correlate the year as determined by the Sun with the day and lunar month. As early as 2500 B.C., for example, the Egyptians adopted a solar year of 365 days, but later found that in contained more nearly 365¼ days.

Likewise the lunar month was found to contain about 29, 5 days and not a convenient 30 days. Twelve lunar months therefore totaled 354 days instead of the 365 ¼ days of the solar year. As a result all manner of ingenious devices were introduced to form a reasonably reliable calendar, but it remained a problem right up to modern times. Even today we must add an extra day to February once every four years to ensure an average year of 365 ¼ days: the calendar months are by no means equal in length: en Easter arrives sometimes in March and sometimes in April.

Nut. Louvre Museum

Astrology

The Babylonians were the great star-worshipers and astrologers of antiquity. To them the heavenly bodies were gods and goddesses to whom it was necessary to pay homage. Night after night they recorded on clay tablets the position of whatever planet happened to be visible, thereby building a body of knowledge which led them to discover further regularities in the sky. After about the seventh century B.C. they were able to forecast well in advance when this or that planet would be in a particular part of the sky, or on what dates two or more planets would appear to meet. By the second century B.C. they could even predict eclipses of the moon with fair accuracy, for they discovered that eclipses which occur during a cycle of roughly 18 years repeat themselves in the subsequent cycle.

There is little doubt that astrology, or the belief that human affairs can be foretold by taking notes of events in the sky, stemmed directly from Babylonian star worship. Once established, it persisted in one form or another in several areas of scientific activity for many centuries. It certainly played an important part in astronomy, and more often than not, the two subjects were regarded as one. The association ended in the 17th century with the rapid rise of the physical sciences. Astrology had nothing to contribute to the scientific approach and therefore dropped into well-merited obscurity.

Nut Geb and Shu. The Egyptian sky-goddess Nut, with her body arched over the Gods of Air Shu and Earth Geb.

Greek Cosmogony

Greek Cosmogony

The Ancient Greeks

Astronomy owes a great debt to the ancient Greeks. From them came the idea of a science influenced to some small extent by earlier Babylonian discoveries, but characterized by a completely different outlook. Whereas the priests of Bablyonia and Egypt tended to keep their astronomical knowledge to themselves, the thinkers of ancient Greece were philosophers, or “lovers of wisdom”, who operated quite openly through observation, discussion and argument.

The new approach to understanding the nature of the physical world was almost wholly deductive. True, the Greeks made valuable observations, but the general trend was to fit observation to theory instead of basing theory on observation. In astronomy they were concerned with a knowledge of the nature and structure of no less than the entire physic universe. This study, known as cosmology, was based largely on geometry, for to the Greek mind all celestial motions were derived from the principle of uniform motion in a circle.

Greek Cosmogony. Photo by Elena

The Universe According to Aristotle

About 600 B.C. Thales of Miletus, the first of the great  Greek astronomers, taught that the changes in the heavens were not due to the caprices of gods but to known physical processes.  Anaxagoras, one of his followers, understood the causes of eclipses and stated that just as the sun and moon were material and not spiritual bodies, so the stars were merely white-hot stones whirled round by the vault of heaven. But the most important contribution in this earlier Greek period came from Pythagoras. Considerations based on geometry mixed with mysticism led him to depart from the old idea of a flat earth. The earth, he declared, is round like a ball and is fixed at the centre of the universe without any visible signs of support. Philolaus, one his disciples, went even further by teaching that the earth, in common with the sun, moon, and planets, moves in a circle about an invisible central fire which he called “the hearth of the universe”.

The ideas of Philolaus were decidedly unpopular with other Greek thinkers. To them nothing seemed more obvious than that the Sun and stars should travel about the Earth. They welcomed the idea of a round earth, for this accorded with observation. For one thing, a comparatively short journey North or South brought about a change in appearance of the starry sky. Certain southern stars  seen in Egypt were invisible in more northerly latitudes, while some of the northern stars that rose and set in Egypt stayed permanently above the horizon on the Greek mainland. These changes could not possibly take place if the earth were flat. Again, as Aristotle pointed out, when the moon was being eclipsed the earth`s shadow had a circular edge, which in fact indicated that the earth had a circular boundary.

Aristotle, born in 384 B.C., a pupil of Plato and the friend and tutor of Alexander the Great, had a profound effect on subsequent thought. According to him the universe was arranged in concentric layers like those of an onion. At the centre was the fixed spherical earth, above whose rocky core stretched the layers of the elements water, air, and fire. The last extended to a crystalline shell or sphere which completely enclosed the earth and in which the moon was embedded.

Within the sphere of the moon all was change and corruption, a scene fit for brutes and men and such transient things as rainbows, shooting stars and comets. Above the lunar sphere stretched regions celestial, divided by the successive crystalline shells of Mercury, Venus, the Sun, Mars, Jupiter, and Saturn. Here all motion tended to be circular, uniform, and perpetual. Enclosing the whole was the vast sphere in the full sense of the word, which came under the direct influence of the Primum Mobile or Divine Mover. This outer Sphere rotated uniformly once in 24 hours and communicated its motion to all other spheres.

Diagram of Aristotle`s Universe. A fixed central earth is surrounded by the concentric shells of the heavenly bodies

Signs for All Times

Signs for All Times

Clues to your personality from palm-reading the heavens

Most horoscope columns are based on sun sign astrology, which is based only on one’s birth date. Genethliac astrology factors in a wealth of other information, including a person’s time and place of birth, the location of the sun, moon, planets, and some asteroids, and the path of the moon’s orbit around the earth.

Here’s a beginner’s guide to what your sign may reveal about you.

Aries: March 21 – April 19. The Ram. Aries represents birth, and it is the first sign of the zodiac. As the first zodiac, the ram is like a baby – very self-absorbed. And like a baby, Aries puts his or her needs first. The Ram is fearless, extremely honest and direct, and very gung ho. Arians often show a ferocious temper, but after the fight, they don’t hold a grudge. With all the energy they expend, you have to wonder when they relax. But they can be calm too. They find their soulmates in Sagittarius, Scorpio, and Cancer.

Taurus: April 20 – May 20. The Bull. Taurus is a rocky coast that’s been beaten by the elements for centuries. Those born under this sign are strong and stubborn with a quiet demeanor. Taureans are steady, speak sparingly, and possess an inner strength, but don’t like change. They are outstanding workers who are willing to take orders without resentment. Their hearts and pockets are open to a friend in distress, but they may have trouble expressing their own feelings. Cancer, Leo, and Capricorn will hit it off with them.Gemini: May 21 – June 20. The Twins. Being born under the sign of the Twins means you never know when you might switch your looks, house, jobs, or spouse on an impulse. Geminis can never get enough money, fame, or love. They live by their own rules and do what they want; they have little patience for indecisive people and can be very rude, selfish, and immature. The Gemini women has a hard time committing herself to one man at a time, and the Gemini man may shower a love interest with flowers, but he’s unlikely to reveal his innermost core. Still, Gemini will be drawn to Leo, Capricorn, and Aquarius.

Dinosaur. Why can’t we introduce the Dinosaur Zodiac Sign? Photo: Elena

Cancer: June 21 – July 22. The Crab. The Cancer person is full of laughter and loves a good joke. But at other times Cancer’s moods are blacker than the darkest cavern. Yet people born under this sign also are sweet and gentle and will find a way to rise above adversity when the moon changes. Cancerans are very sentimental about their roots and their family. They have vulnerable hearts and very sensitive feelings. In love, the Cancer person can be so dependant it can border on obsession. Virgo, Leo and Aquarius will be the most compatible.

Leo: July 23 – August 22. The Lion. Leo is the leader of the jungle, a dignified, stately presence, lying luxuriously in the sun for all to see. Leos have extremely strong personalities and can be very vain. But they also are very loveable, seldom waste energy in fruitless tasks, and are good organizers. The regal ways of the Sun sign make them great hosts or hostesses. Leos like the regal treatment and spend money freely, but they’ll also give money to almost anybody. They play hard, work hard, rest hard, and live hard. Leo will want to meet Pisces, Aries, and Gemini.

Virgo: August 23 – September 22. The Virgin. These perfectionists are dependable, industrious, practical, cool, and sincere. They are blessed with great curiosity and are very mentally alive, excelling in both the written and spoken word. The Virgo can endure and thrive on intense work longer than most others. They can also destroy relationships by being too critical, analytical, and irritable. But if you’re in a jam, the Virgo will gladly roll up his or her sleeves and jump in. Capricorn, Aries, and Pisces, are for Virgo.

Libra: September 23 – October 22. The Scales. Being the sign of the Scales, the Libra is a natural balancer. They’re excellent listeners, but they’ll talk your ear off. They are extremely intelligent, but extremely naive. They love people, but hate crowds. They’re gracious, caring, and calm, but when the weight of the scales change, they can be stubborn, annoying, and depressed. The Libran hates arguments, and makes an ideal mate. They will do anything to please. Gemini and Taurus stand the best chance of benefiting.

Scorpio: October 23 – November 21. The Scorpion. The most passionate people in the zodiac, Scorpios are nocturnal creatures. They have hypnotic intense eyes which make many people feel nervous. Scorpios have very strong emotions, but they are deeply hidden. They know what they are and what they’re not and nothing anyone says will change that. They can be sarcastic, stubborn, and even cruel to those that are close to them. It is extremely hard to get to know them. They must test everyone before they show their real selves. Scorpions are fascinated with death and religion. Scorpio will appreciate Cancer and Aquarius the best.

Sagittarius: November 22 – December 21. The Archer. When you start a new job, the first person to walk up to you with a smile, shake your hand and welcome toy aboard is a Sagittarius. Sagittarian mean well but are always putting a foot in their mouth. They make friend easily, are optimists, and refuse to take life seriously. But they can have violent tempers and are bad at keeping a secret. They have fantastic memories but can’t remember where they left their keys. Pisces, Cancer, and Leo will be most understanding.

Capricorn: December 22 – January 12. The Goat. Like the goat, the Capricorn looks and acts harmless but is tough as nails. Capricorns are steady, serious, and sensible, and never let obstacles or disappointments block the way to the top of the mountain. They are gentle and persuasive, and although they are sometimes labeled as snobbish, that’s really not true. The Capricorn person is safe to trust and confide in, and they make great providers. Leo, Aries, and Virgo are Capricorn’s favorites.

Aquarius: January 20 – February 18. The Water Bearer. Freedom-loving Aquarians are unpredictable and secretly delight in shocking others with their erratic behavior. They are natural rebels with a dreamy look in their eyes. The Aquarium will seek the security of crowds and then demand to be alone. When it comes to friends, they seek quantity, rather than quality. Trusting people isn’t natural for Aquarians, but they love to network. Sagittarius, Taurus, and Libra will be the most in sync with Aquarius.

Pisces: February 19 – March 20. The Fish. Like their namesake, fish people have to be in the same spot for too long. They are always swimming from one spot of light to another. Pisces people are the most spiritual of the signs; they are often mystical, impressionable, and intuitive. They are also creative, clever, and sarcastic, and hate to answer a direct question. Yet no sign is more sensitive to human suffering. They love to help. Pisces will find Virgo, Gemini, and Scorpio to their liking.

Criterion Telescopes: Great performance

Performance is the First Reason You’re Proud to Own a Criterion

(Astronomy, august 1976)

In telescopes, “excellence is as excellence does.” The Criterion instruments, with unsurpassed optics, rank among the world’s most widely praised, because they perform brilliantly, reliably and with satin-smooth, effortless ease. The more demanding the conditions of use, the more you appreciate the ability of your Criterion to deliver exciting results. Whichever advanced design telescope you select, you get a superbly engineered instrument, guaranteed unconditionally. When you compare the pleasantly surprising prices you find further reason to choose Criterion. Please note that they are not “base” prices, but include everything described at no extra cost. Only Criterion`s leadership in efficient, modern precision production makes these prices possible.

Dynamax 8 8-Inch Schmidt-Cassagrain. For spectaculars results – effortlessly. Extra features without extra price. 

This “never before” telescope created by Criterion gives you Schmidt-Cassegrain advantages at their best: full 8” aperture, wide field, with flawless resolution, yet weighs only 30 pounds for one-hand portability. It offers unprecedented versatility for viewing, superb telephotography, terrestrial uses, or technical applications. The exquisite optics, combined with super-precise electric drive plus variable drive corrector, combine to insure unsurpassed, unsurpassed, unequalled ease of use because the extra features so necessary for superior results are designed-in and built-in, and included in the price.

Dynascope RV-7 6-inch Newtonian

AC, DC, and manual drives (variable, not just solar). You can easily dial in lunar, solar, sidereal, planetary, etc. rates while observing for extra long monitoring. Large 8X50 finderscope has micrometer screw focusing. Toggle switch with pilot light. Engraved setting circles, observable from viewing position. Three eyepieces included. Star diagonal, latitude adjusters, photo and telextender adaptors, and custom, fitted case. Ready for Total Performance with nothing else to buy!

Dynascope RV-6 6-inch Newtonian. For Exciting Viewing, Superb Value. Price includes built-in precision electric drive.

Professionals and astute amateurs and school or college users by the thousands know the breathtaking performance, this pace-setting telescope achieves. Esquisite optical system includes f8 parabolic aluminized mirror, guaranteed to reach all theoretical limits of resolution and definition. Highly accurate Electric Drive uses regular AC, has smooth, self-acting clutch, permits manual operation. Two 1 ¼ eyepieces, 70X and 140X, included (others available). Highly stable equatorial mount with solid tripod, adjusts ascension and declination. Tube rotates for adding cameras and comfortable viewing. Easy, quick portability. Smooth, brass rack-and-pinion focusing. Handsome, white 50” Bakelite tube maintains perfect collimation. 6X30 finderscope. Fine workmanship throughout.

Criterion Manufacturing Company…