El Universo no parece ni benigno ni hostil, simplemente indiferente a las preocupaciones de seres tan insignificantes como nosotros. - Carl Sagan

Hay un geocentrismo práctico en nuestra vida diaria. Todavía hablamos del Sol que sale y se pone, en lugar de hablar de una Tierra que gira. Todavía pensamos en un universo organizado para nuestro beneficio y poblado tan sólo por nosotros. La exploración del espacio, en este sentido, nos hará ser un poco más humildes.

When an object impacts the Moon at high speed, it sets the Moon slightly wobbling. Eventually the vibrations die down but not in so short a period as eight hundred years. Such a quivering can be studied by laser reflection techniques. The Apollo astronauts emplaced in several locales on the Moon special mirrors called laser retroreflectors. When a laser beam from Earth strikes the mirror and bounces back, the round-trip travel time can be measured with remarkable precision. This time multiplied by the speed of light gives us the distance to the Moon at that moment to equally remarkable precision. Such measurements, performed over a period of years, reveal the Moon to be librating, or quivering with a period (about three years) and amplitude (about three meters), consistent with the idea that the crater Giordano Bruno was gouged out less than a thousand years ago.

We must surrender our skepticism only in the face of rock-solid evidence. Science demands a tolerance for ambiguity. Where we are ignorant, we withhold belief. Whatever annoyance the uncertainty engenders serves a higher purpose: It drives us to accumulate better data. This attitude is the difference between science and so much else. Science offers little in the way of cheap thrills. The standards of evidence are strict. But when followed they allow us to see far, illuminating even a great darkness.