Math and Science Discover the Unseen Planets of Trappist-1 – Now That’s Cool!

I am sure by now you have heard about NASA’s discovery of 7 – earth-like planets orbiting the star called Trappist-1 by using the Spitzer Space Telescope. And, apparently 3 of them could possibly be habitable for life. All of this is amazing in itself, but, what is even more amazing is they discovered these planets without really even seeing them.

What?!  How is this possible? How do they know then that there are even planets if they can’t see them? It all comes down to some amazing technology, some data collection, a lot of math, science and analysis. If you are looking for ways to get your students excited about math and science and real-world applications to answer questions, you need look no further.

While listening to a story on NPR, as usual, an astronomer came on to discuss how these planets were in fact discovered. In his discussion, I was just floored by all the applications of geometry and statistics used in this discovery. When he said they couldn’t actually ‘see’ any of the planets, but instead, used the dimming light of the star, Trappist-1, that these planets orbit around as an indication that there were in facts objects/planets orbiting about the star. So – basically,  looking at the stars brightness from the Earth, the amount of starlight that is blocked as each planet passes across the view of the star was used to calculate the size of each planet.  Based on the amount of dimming, they were able to determine the size of the planets, relative to Earth, with the dips in the stars light indicating how fast the individual planets were orbitting the star. This video below explains the process really well:

The star, Trappist-1, is what they call an ultra-cool dwarf star, which is about the size of Jupiter and significantly cooler than our own sun, and is only 39 light years away from us.  That seems far to me, but apparently in ‘space units’ that’s really close! (Here’s a great problem for students – how many miles would 39 light years represent?) Each planets mass was determined by the amount of tug of each planet on the other. Then, using the size and mass calculations, they estimated each planets density, which then allowed them to extrapolate that six of the planets are probably rocky. Another really interesting thing about all the planets is they appear to be tidally locked, which means the same side of the planet always faces its sun, so one half of the planet is always dark, the other always light. This is based on the length of each planets day, or its spin on its axis (determined by watching the planets for a period of days and seeing how often they crossed the star). The shortest day (compared to an earth day) is 1.5 days, the longest is about 20 days (they still have to collect more data for this last one). I found this great chart on the NASA Jet Propulsion site that compares each of the seven planets (with an artist’s rendering of what they might look like…remember, no one can actually ‘see’ these planets yet)

This infographic displays some artist's illustrations of how the seven planets orbiting TRAPPIST-1 might appear — including the possible presence of water oceans — alongside some images of the rocky planets in our Solar System. Information about the size and orbital periods of all the planets is also provided for comparison; the TRAPPIST-1 planets are all approximately Earth-sized.

This infographic displays some artist’s illustrations of how the seven planets orbiting TRAPPIST-1 might appear — including the possible presence of water oceans — alongside some images of the rocky planets in our Solar System. Information about the size and orbital periods of all the planets is also provided for comparison; the TRAPPIST-1 planets are all approximately Earth-sized.

I find the whole process exciting, interesting, and fascinating. I think students would too and there is so much application of mathematics and science going on here. And, as a certified sci-fi geek, just thinking of the possibilities of other life on those ‘M’ class planets (shout out to my fellow Star Trek groupies) is sparking my imagination. Right now, we don’t have the technology to see these seven planets, but who knows? Maybe a student who explores the math and science behind these now might create that next telescope that lets us see the planets, or the space ship that allows us to travel there? Fun to imagine, and fun for students to explore these ‘brave new worlds where no man has gone before….”.

If you are interested in finding out more about this Trappist-1 discovery, here are some more links:


Math in the Movies – Let’s go to Mars

Last night I watched the movie The Martianstarring Matt Damon and directed by Ridley Scott. I really enjoyed it because I am a sci-fi fan, but even more so when I realized how much math and science was in the movie. I mean – it’s all about the math really. (I would like to say, for the record, that it is NOT a comedy, even though Matt Damon won best actor in a comedy at the Golden Globes.  Funny moments, yes, comedy?No)

If you have not seen the movie, do so. I am going to be sharing some links that will definitely have spoiler alerts in them and I will probably even share some spoiler alerts myself, so I suggest not reading if you have not seen the movie.  

As I said, the movie is all about math and science – to survive, to communicate, to pull of a dramatic rescue. It reminded me at times of another great sci-fi space movie, Apollo 13, which also involved a space rescue. As in Apollo 13, there are scenes in the Martian where scientists/mathematicians on earth are testing out theories and calculations on replicas on earth so Matt Damon’s character, Mark Watney, can then perform the same things on the real equipment on Mars. There are also numerous mathematical and science calculations and experiments that Mark Watney does during his long time alone on Mars to try to survive – many of which go horribly wrong, but that’s what makes it so realistic and such a great example for students, because if you mess up, you try again and try a new approach.  And sometimes the obvious solutions aren’t the best solutions.

I am not going to go into all the math and science in the movie, because other people have done a great job of that already. What I am going to encourage is that math and science teachers use the math and science from The Martian in your classroom. Bring the movies into your classroom and see the fun students will have applying mathematics and science in an engaging way with something that is of interest to students. When Apollo 13 came out in 1995, I was teaching 6th grade mathematics on a collaborative team. We did a ‘field trip’, taking students to see Apollo 13 and then doing a lot of math/science/english/history activities to bring what they saw back to the classroom to connect to what they learned. One activity I specifically remember is having students work with partners. One partner had to build a structure (we used Legos) and write down what they did, and then read the directions to the other person and see if the other person could make a replica of what they’d built. The idea here was to emphasize the importance of good instructions, logical sequence, etc. But – it simulated the scene in the movie where the scientists on earth had to basically make a square peg fit into a round hole and create a structure that would clean the air in the module so the astronauts would live.  And they had to tell the astronauts what to do clearly and quickly or they would die, and only through their voice – so good descriptions and logical steps. We did a lot of other activities, but what I remember most is how engaged and excited students were to be using their writing, their math, their science, their history, to expand on and understand the movie.

Here are several of the articles and links I have found related to the math/science in The Martian.  Choose a couple and explore with your students and see how much fun you and they have!

  1. Math of “The Martian”: How It Adds Up, Sarah Lewin
  2. “The Martian” is Full of Math Word Problems, Says Author Andy Weir, by Liana Heitin
  3. Do the Math: How to Survive in “The Martian”, by Kari Tate
  4. The Science of “The Martian”: 5 TED-Ed Lessons to Help You Understand the Film, by Laura McClure