As we said, the ancient Babylonians began making systematic observations of the heavens by 3000 B.C.E., and the Chinese weren’t far behind.

Records exist that show they had observed a grouping of bright planets (called a conjunction) that occurred around 2500 B.C.E., and, sometime before this, had arrived at the concept of a 365-day year, based on what appeared to be the sun’s annual journey across the background stars. Why the Emperor Executed Hsi and Ho

Like human beings everywhere throughout history, the Chinese in ancient times were a self-centered people. In fact, the Chinese word for their own country means “Middle Kingdom.” Their belief was that the objects in the heavens had been put there for the benefit of humankind in general and for the emperor in particular. Perhaps for this reason, they felt particularly threatened when, occasionally, something seemed to take a bite right out of the sun, then nibble away, gradually and ominously darkening the sky and the earth below.

The Chinese reasoned that a great dragon was attacking the sun, trying to consume it, and that since it was a beast, it might be susceptible to fear. So, in the midst of an eclipse, people would gather to shout, strike gongs, and generally make as much noise as possible—the more noise the better, since the beast was very big and was certainly very far away. Eventually the noise appeared to always scare off the dragon. Because it was important to assemble as many people to make as much noise as possible, it was of inestimable value to get advance warning of an eclipse.

With infinite patience, generations of Chinese astronomers observed solar eclipses and discovered something they called the Saros, a cycle in which sun, moon, and earth are aligned in a particular way every 18 years, 11.3 days—more or less. Armed with a knowledge of the Saros, the Chinese were able to predict eclipses—usually.

We know of this because in 2136 B.C.E. there was an unpredicted eclipse, which caught the noisemakers unawares. It was only by great good fortune that the sun wasn’t consumed entirely. The Imperial Court astronomers Hsi and Ho weren’t so fortunate. They were executed for having fallen down on the job. (The royal astronomer position may have been particularly difficult to fill after the “departure” of Hsi and Ho.)

Time, Space, Harmony

More than 4,000 years later, the fate of Hsi and Ho is still regrettable, but not nearly as important as the fact that we know about their fate at all. The Chinese made records of their astronomical observations and, indeed, along with the Babylonians were some of the earliest people to do so.

 Some oracle bones (animal bones used to foretell the future) from the Bronze Age Shang dynasty (about 1800 B.C.E.) bear the early Chinese ideogram character for “pillar.” Scholars believe that this ideogram is associated with a gnomon, a pillar or tower erected for the purpose of measuring the sun’s shadow in order to determine, among other things, the dates of the solstices. Writings from the Zhou dynasty, in the seventh century B.C.E., reveal that a special tower was built to measure the sun’s shadow.

 During the Han era (C.E. 25–220), the town of Yang-chhêng was judged to be the center of the world, probably because the principal gnomon was installed there (or the gnomon may have been installed there because it was considered the center of the world). By C.E. 725, many smaller gnomons— what might be called field stations—were set up along a single line of longitude extending some 2,200 miles from the principal gnomon at Yang-chhêng. With this system, the Chinese could calculate calendars with considerable precision. In subsequent eras, even more elaborate gnomon towers—observatories, really—were built, including that of the astronomer Guo shou jing at Gao cheng zhen in Henan province, in C.E. 1276. Why this passion to measure the heavens and the passage of time? Living in harmony with nature has always been important in Chinese philosophies, and, in terms of practical politics, exact knowledge of the heavens aided rulers in establishing and maintaining their absolute authority. Babylon Revisited

Back in Babylon, by the sixth century B.C.E., astronomers were tabulating in advance the intervals between moonrise and moonset and between sunrise and sunset, as well as the daily shift of the sun with respect to the background stars. They also predicted eclipses and made elaborate attempts to explain planetary movement.

The Venus Tablet

Some time between 1792 and 1750 B.C.E., during the reign of Hammurabi, the Babylonian king who gave the world its first code of laws, the so-called Venus Tablet was inscribed, devoted to interpreting the behavior of that planet. Babylonian astronomers believed that the movements and positions of planets with respect to the constellations could influence the fate of kings and nations. This interest in the positions of planets as a portent of the future was one early motivation for careful study of the heavens. Using binoculars or a telescope, you may be able to see Venus in its phases, from thin crescent to full. During much of the year, the planet is bright enough to see even in daylight, always quite near the sun. Venus is closer to the sun than we are, and that fact keeps it close to the sun in the sky (never more than 47 degrees, or about a quarter of the sky from horizon to horizon). The best times to observe Venus are at twilight, just before the sky becomes dark, or just before dawn.

The planet will be full when it is on the far side of the sun from us and crescent when it is on the same side of the sun as we are. With a telescope on a dark night, you may be able to observe the “ashen light” phenomenon. When the planet is at quarter phase or less, a faint glow makes the unilluminated face of Venus visible.