Introduction to Chapter1: The Solar System
Going out at night to look at the bejeweled and mysterious sky is not something we usually do. People of ancient and prehistoric times turned their eyes to the sky every night because the motions of the Sun, Moon, stars and planets served as their calendar, clock, and compass. The sky told them when to plant and harvest their crops, when the game herds would migrate, and the direction in which to travel. Knowledge of the sky was not only necessary for survival-the sky was also worshipped as the home of the gods. Viewed in this way, the sky gave people mixed feelings of awe, insignificance, and peacefulness. Ever since the first stirrings of consciousness, humankind has lifted its eyes towards the mystery of the heavens and found solace in the contemplation of celestial objects. The heavens seemed so calm and eternal and comforting.
However, the quietude of the universe is an illusion. The stars in the sky are not eternal; they are born from nuclear fires, they live, and ultimately die. Some stars die quietly, some literally tear themselves apart with violent explosions, and still others leave the visible universe when they die to become the most exotic objects in the known universe-black holes.
Beyond the stars in our Milky Way Galaxy are other galaxies-and sometimes one of these galaxies, containing billions of stars, will collide with and consume another galaxy like a cosmic cannibal. Comets and asteroids restlessly roam through space, sometimes crashing into planets and moons with catastrophic results.
The night sky seems so peaceful, yet masks a maelstrom of activity that we are not easily able to detect with our eyes alone. How can we, when we cannot even detect our own motions? The Earth is spinning around at up to 700-1100 km/hr, depending on latitude, and orbiting around the Sun at 30 km/s; the Sun is orbiting the center of the Milky Way Galaxy at 250 km/s, and the Milky Way Galaxy itself is moving through spacetime. The Sun and Solar System travel 971,000,000 km every year in their orbit around the galactic center. (How many galactic miles have you traveled so far in your lifetime?) We are on a roller coaster ride of universal proportions, and we feel nothing. How very strange is this world we inhabit!
The rate at which we receive new information and expand our knowledge in astronomy has increased phenomenally. This is due in part to sophisticated technology such as the earthbound Keck Telescope on a mountain top in Hawaii, and the Hubble Space Telescope orbiting the Earth. When we see the constant stream of beautiful images from these instruments, it is easy to forget that humankind gained an incredible depth of understanding of our local universe by visual observation with the aid of a fewsimple astronomical tools. Making observations over periods of time, recording data, and developing predictions from the analysis of the data, is still how science works, no matter how glitzy or high-tech, or even how simple, the tools we use are.
You have the ability to travel to the far reaches of space. You can make a journey through your eyes and mind that would otherwise be physically impossible due to the immense distances involved. Traveling at 968 km/hr by 747 jet, it would take 17 years to reach the Sun, and an amazing 4,600,000 years to reach just the nearest star! We cannot travel to the stars, but we can still come to know them well by reading the messages they sent out a very long time ago.
So let the stars get in your eyes and become initiated into the wonders of the universe from your own backyard. Your life will be enriched with a newfound knowledge as you learn how to read the messages encoded within the starlight traveling through spacetime and falling into your eye. You will be able to use this information to understand the unstable and violent nature of seemingly peaceful and stable stars. So look up! Watch the stars! Get to know the stars and constellations, make a quadrant, learn how to use a planisphere, and begin to enjoy the pleasures of the cosmos!
