A Random Walk
The Earth and the other Planets 14 Billion Years to 4.6 Billion Years
Walk outside and look at the sky tonight just after sunset. Chances are you will find two or three particularly bright objects that stand out among the stars, even in the haze and illumination of a city. They do not seem to twinkle like stars, but shine steadily. If you looked at them through binoculars, they would appear to be small disks.
If you look at the same bright objects on successive nights, you will notice that over a period of weeks or months, they seem to wander among the stars, never appearing in exactly the same place two nights in a row. The Greeks called them “wanders”or planets and assigned them names of gods (although we use Roman names). In the evening and morning, for example, you are likely to see Venus, the goddess of love, and swift moving Mercury, the messenger of the gods; and the night sky is often dominated by Jupiter the king of the gods. Today we know that these disks of light in the sky are objects similar in many ways to our own planet, Earth. They show us that we are part of a system that includes not only Earth, but the Sun and the other planets as well. Our probes have visted all of them. They have landed on two Venus and Mars, and between 1969 --- 1972 we launched seven maned mission to the moon. Only one failed to reach the moon. Visionaries talk of the day when science fiction will become reality and human beings will work and live on these, our nearest heighbors in the cosoms. In every sense of the word, the planets are the next frontier.
