G8_ Are We Alone?_grade level_02

“Are we alone?” is a question many of us contemplate as we investigate the vast darkness of space. To quote the late great Dr. Carl Sagan, “The universe is a pretty big place. If it’s just us, seems like an awful waste of space.” It is this very vastness of space that prevents us from knowing more than we do about the universe we live in.

In 1969, Neil Armstrong and Buzz Aldrin landed on the Moon. Imagine how the nation felt as it watched the live television broadcasts of Neil Armstrong climbing down the ladder from the Lunar lander, the Eagle. As his foot hit the ground, he made his now famous statement, “One small step for man, one giant leap for mankind.” That same signal was not only beamed back to Earth, but those same signals also radiated off into space. Travelling at the speed of light, they started their journey out into the vastness of space.

Television transmissions, like radio waves, are a kind of electromagnetic radiation, and thus they travel at the speed of light. The speed of light is approximately 300,000 km per second. At that speed, a beam of light could go around Earth at the equator more than seven times in a second, but compared to outer space, that’s a very short distance.

In fact, if the Sun were somehow turned off, we wouldn’t know for another eight minutes, as that is how long it takes for light to travel from the Sun to Earth. It takes almost two years for light to reach the Oort Cloud, a collection of dormant comets at the limits of our own solar system.