top of page
  • Writer's pictureolivershearman

Hunting aliens with maths: The Drake Equation 

Welcome alien interested individuals! If you're as fascinated by the mysteries of the universe as I am, you're in for a treat. Today, we're diving deeper into the Drake Equation, a formula that's not just a staple in astrophysics but a beacon of wonder for anyone intrigued by the possibility of alien life. 

The Drake Equation: A Closer Look

Imagine standing under a starlit sky, telescope in hand, just like Frank Drake once did, pondering the vastness of space and the potential for life beyond our planet.

Frank Drake's equation, introduced in 1961, is a formula designed to estimate the number of active, communicative extraterrestrial civilizations in the Milky Way galaxy. It compiles various astronomical and biological factors into a single, thought-provoking equation:

N = R_* x f_p x n_e x f_l x f_i x f_c x L

Each term in this equation opens a window to a different aspect of the cosmic puzzle:

- R_*: The birth rate of stars in our galaxy.

- f_p: The percentage of those stars that host planetary systems.

- n_e: The number of planets per solar system with the potential to support life.

- f_l: The likelihood of life actually developing on these planets.

- f_i: The chance that this life evolves into intelligent beings.

- f_c: The probability of these intelligent beings developing advanced technologies.

- L: The duration these civilizations release detectable signals into space.

The first term, R_*, indicates the average rate of star formation in our galaxy. This rate can vary, but current estimates suggest that about 1-3 new stars are formed in the Milky Way each year. Understanding star formation is crucial as it sets the stage for the development of planets where life could potentially arise.

Next, f_p represents the fraction of those stars that have planetary systems. With the advent of powerful telescopes like Kepler, we've found that planets are common in our galaxy, leading many scientists to believe that most stars have at least one planet, suggesting f_p could be quite high.

The term n_e is the average number of planets that could potentially support life per star with planets. This number is highly speculative, as it depends on several factors, including the planet's distance from its star, which determines whether it could have liquid water – a key ingredient for life as we know it.

Following this, f_l is the fraction of planets that could support life that actually develop life at some point. This factor is one of the greatest unknowns. While Earth is teeming with life, we have yet to find definitive evidence of life elsewhere in the universe.

The fifth term, f_i, is the fraction of planets with life that eventually develop intelligent life. This step is a huge leap, as it involves many complex and possibly rare biological processes.

Next, f_c represents the fraction of civilizations that develop technology to communicate their existence into space, such as radio signals. This is another significant leap, as it not only requires the development of intelligent life but also a civilization advanced enough to develop such technologies.

The final term, L, is the length of time such civilizations release detectable signals into space. This could range from a few decades to thousands or even millions of years, depending on the lifespan of the civilization and its technology.

The Pursuit of Extraterrestrial Intelligence

The Drake Equation is more than a theoretical construct; it's a guiding star in the search for extraterrestrial intelligence (SETI). By breaking down the quest into manageable questions, it provides a structured way to approach the enigma of alien life. For instance, as we learn more about exoplanets (planets outside our solar system), we gain insights into factors like f_p and n_e. Similarly, advancements in biology and technology inform our understanding of f_l, f_i, and f_c.

Estimating the Odds of Alien Life

The real magic of the Drake Equation lies in its openness to interpretation. Depending on the values you plug into the equation, the number of potential civilizations can range from zero to millions. This range reflects our evolving knowledge and the uncertainty inherent in such a grand cosmic question. It's a reminder that in science, sometimes the journey is just as important as the destination.

Why the Drake Equation Belongs in Classrooms

Bringing the Drake Equation into middle and high school classrooms is a fantastic way to ignite a passion for science and the unknown. Here's why it's such a valuable educational tool:

1. Interdisciplinary Learning: The equation spans astronomy, biology, technology, and even philosophy, offering a holistic approach to learning.

2. Critical Thinking: It encourages students to analyze data, debate possibilities, and form their own hypotheses.

3. Curiosity and Imagination: It opens young minds to the vast possibilities of the universe, sparking a lifelong love for exploration and discovery.

4. Global Perspective: Understanding our potential place in the cosmos can foster a sense of global citizenship and responsibility.

The Future of Our Cosmic Quest

As technology advances and our understanding of the universe deepens, the Drake Equation continues to evolve. Each new discovery about exoplanets, life on Earth, and the nature of intelligence adds another piece to this cosmic puzzle. Whether we find that we're not alone in the universe or that life is a unique Earthly phenomenon, the journey of discovery will undoubtedly reshape our view of the cosmos.

If you are interested in a teaching resource that aligns with the Drake equation, perhaps my science article on the topic will be of use - offline version here / Google suite version here

The Drake Equation is more than just a set of variables; it's a symbol of our quest to understand the universe and our place within it. It teaches us to question, to explore, and to dream. So, whether you're a student, a teacher, or simply a curious soul, remember: the stars above are a canvas of possibilities, each one inviting us to ponder, "What if?" Keep looking up, and keep wondering – for in the quest for knowledge, every question, every thought, and every gaze towards the heavens brings us closer to understanding the grand tapestry of the cosmos.

Thanks for reading. 

Cheers and stay curious

Oliver  - The Teaching Astrophysicist

35 views0 comments

Recent Posts

See All


bottom of page