Since the dawn of existence, humans have wondered: What are these twinkling lights in the sky? Why do they shine? How far are they from us? Why does the Sun shine so brightly? What fuel burns within it? How vast is the sky? How large is the universe? How did the universe come into existence, and how will it end? Do other celestial bodies in the universe host life like Earth? Are we alone, or do we have companions out there?

To answer these questions, for thousands of years, humans have studied the movements and positions of stars and planets. Various models of the universe were proposed. However, we only began to receive accurate information about the structure of the universe and the physical properties of its celestial bodies within the last two hundred years. Most of this knowledge has come since the beginning of the last century, especially after the advent of space exploration. Although astronomy is the oldest science, our understanding of the universe's structure and expanse has only developed substantially in the last three hundred years. This book encompasses that body of knowledge.

In August 2006, the International Astronomical Union introduced a new definition of a "planet," reducing the number of "major planets" in our solar system to eight. Pluto, Eris, and the asteroid Ceres were reclassified as dwarf planets. This new arrangement and its explanation are included in this book.

### Preface:

For early humans, the knowledge of time and direction was a physical necessity, and this knowledge could only be gained by continuously observing the movements of celestial bodies. Through millennia of accumulated experience, ancient humans realized that their food supply—wild animals and plants—was connected to the seasons, and understanding the cycle of seasons came from observing the movements of the Sun and stars.

Ancient humans believed that their food supply was influenced by the movements of celestial bodies. This belief extended to their lives, and thus, astrology was born. In Bronze Age civilizations, priests served as astrologers, and temples acted as observatories. These priest-astrologers represented mysterious natural events through symbolic deities and provided information about time to both rulers and people. As a result, they were highly respected in society. By continuously studying the movements of the Sun and Moon, these astrologers eventually became able to predict eclipses, which increased their stature and influence even further. People began to think that these astrologers, who could speak about time and predict fearsome events like eclipses, could also predict future events in human life.

Thus, predictive astrology emerged within the role of the priest-astrologer. In Vedic times, the priest-astrologers of the Atri family tracked and predicted eclipses. Similarly, in Babylon during the time of Hammurabi (18th century BCE), priest-astrologers not only predicted eclipses but also foretold the future of kings and their kingdoms. Driven by the lure of respect and wealth, these priest-astrologers cloaked their knowledge in mystery and kept it confined to their own class for centuries.

However, they could manipulate the imaginary forms of their deities to fit changing social, political, and economic circumstances, but they could not alter the consistent movements of the celestial bodies. This distinction led to a division in the profession around the first century CE in India, with one group becoming priests and the other astrologers. Nevertheless, mathematicians who practiced mathematical astrology also dabbled in predictive astrology. Some leaned more toward mathematical astrology, while others toward predictive astrology. Aryabhata (born 476 CE) is considered a great mathematician-astrologer, while the texts of Varahamihira (6th century CE) still serve as a treasure trove of knowledge for predictive astrologers.

From the development of astronomy or astrology (as seen in Appendix 1), it becomes clear that as long as celestial observations were confined to their apparent movements and positions, mathematical astrology bore the weight of predictive astrology. However, when physical science was born and the physical properties of stars and planets were investigated, giving rise to astrophysics, predictive astrology based on ignorance and superstition faced two choices: to fade away or to separate itself from astronomy. Predictive astrology did not vanish. By around 1600 CE in Europe, astronomy began to break free from this superstition and rapidly advanced. Johannes Kepler (1571-1630 CE), who discovered the three famous laws of planetary motion, was still forced to create birth charts, but Galileo (1564-1642 CE), who used a telescope to observe the sky for the first time in 1609-10, refused to bow to such constraints. The year Galileo died was the same year Isaac Newton (1642-1727 CE) was born. Newton gave us new mathematics, a new type of telescope, and the great theory of gravity.

Now, astronomers have moved far from the hustle and bustle of cities and the glow of electric lights. Modern observatories equipped with advanced instruments, located on the peaks of mountains with clear atmospheres, are their new workplaces. Today's astronomers observe radiation, light waves, radio waves, X-rays, gamma rays, and more from stars billions of light-years away and develop new theories based on this new knowledge. The study of the vast universe aids in understanding the minute world, and the study of the minute world aids in understanding the vast universe. Today's scientists are delving into the depths of both worlds, striving to find harmony between them.

And predictive astrologers? They still cling to outdated, incomplete, and unscientific information. Now, they have even taken over television channels. Superstition continues to be printed regularly in many magazines and newspapers. Even today, many leaders in our country, directly or indirectly, support predictive astrology.

However, change is inevitable. We are witnessing a new direction and a new era in the development of astronomy. Until now, our knowledge of the physical properties of celestial bodies was based on analyzing the radiation that reached Earth. But now, humans and their instruments are striving to reach these celestial bodies. Since the dawn of space travel, there has been increased curiosity about the planets and stars. The general public is eager to learn more scientific facts about celestial bodies.

In this book, I present the latest information—illustrated—on the Milky Way, the Sun, planets, moons, asteroids, dwarf planets, comets, meteors, and prominent stars of the sky. The last two chapters explore the beginning and end of the universe and the search for life in the cosmos. The appendices include a brief history of astronomy, data and constants related to astronomy, star maps, and a glossary of terms used in the field.

The book also includes the new solar system classification from the August 24, 2006, International Astronomical Union conference in Prague, where the number of major planets was reduced from nine to eight, with Pluto and other distant objects like Eris reclassified as dwarf planets.

Thus, this book presents an up-to-date scientific introduction to the known universe.