There are billions of stars across our galaxy. We might assume some of them have planets with just the right conditions for life. Of these, we might assume life has formed and developed. But, does this mean there are thousands of inhabited planets out there? Hundreds? Just a few? Or, none at all. Scientists don’t know how many intelligent civilizations might be in our galaxy right now, if any at all, but it’s a fascinating question. This activity will ask you to use some of the information scientists are using to think about the likelihood of intelligent life on other planets.
Your teacher will divide the class into six groups and assign each group a number. Each group should focus on the question on the Anyone Out There? Worksheet that corresponds with their group number. You will have two minutes to discuss your group’s question. There are no “right” answers to these questions. Your job is to make some educated guesses.
For this activity, we are going to estimate that there are 400 billion stars in our galaxy. That’s 400 billion potential locations for life.
Once you have completed your question, share your answer and rationale with the class. Each group will provide another variable to the equation.
If your class ended up with a one or a zero, you collectively predicted that we are alone in the galaxy. A number greater than one means that the group estimated that we could detect another intelligent, communicating civilization close by. A number less than 10 implies that they are far away, and that we won’t be able to detect them soon.
Currently, we only have the technology to detect stars with planets that are a few light years away. Therefore, we’ve only explored a tiny fraction of our galaxy. If we were ever to detect a signal from another intelligent civilization, we would have to figure out what they are saying, how to respond, and then come up with a way to send them a response. However, the biggest problem would be that it would take a very long time to both receive and send the message
In 1961, astronomer and astrophysicist Frank Drake took the six variables your class discussed in this activity and brought them to a SETI meeting. His goal was to get scientists to think about the main things we need to consider when thinking about the probability of communicating with other life.
