The Drake equation estimates how many alien planets we could communicate with, right here , in our own galaxy. All it takes is some multiplication, and best of all, there is no wrong answer because it's based on what YOU think about life in the Milky Way. Before you tackle the equation, take your best guess about how many planets in our galaxy support intelligent life that might communicate with us. Our sun is one of just billions of stars in our galaxy alone. Astrobiologists aren't sure how many stars are in our galaxy.
Estimates vary greatly, but five billion is somewhere in the middle.
One way to search for life on an Earth-like planet is by analyzing the planet's light spectrum for evidence of oxygen, which on Earth is produced by living plants. One way to search for intelligent life is to train a radio telescope on a planet to listen for radio or TV signals. Compare this number to the answer you chose before you did the equation. Remember, there are no right or wrong answers to the Drake Equation. But as researchers begin to pinpoint more exact values for each of the unknown quantities, astrobiologists will gain a firmer basis for estimating how many aliens are out there.