A Day Like No Other: Keeping Time on Mars

Those of you reading The Martian, our ACS ChemClub book selection, are aware of the special timekeeping system that is used for Mars. Instead of keeping track of time by days, it is measured in sols. The main reason for this difference is the way Mars travels through space.

Similar to Earth, Mars moves in an orbit around the sun while at the same time spinning around its own axis. There are a couple of big differences though. For one, it takes Mars about 687 days to make one trip around the sun, which constitutes one Martian year. This is compared to a year on Earth that takes approximately 365 days. The other big difference is how long it takes Mars to spin on its axis, which fictional astronaut Mark Watney points out in the book (p. 18) takes 39 minutes longer than an Earth day. This makes the Martian sol 2.7 percent longer. This might not sound like much difference, but consider that after just two weeks the change would be over 30%, or 7 hours time difference.

To avoid confusion, a day on Mars is called a sol, short for a solar day. You might wonder why this is necessary, and before our modern era of space exploration it didn’t matter as much. But as scientists built and sent remote spacecraft to orbit and land on Mars, it became very important. Spacecraft, especially those that landed on the surface, were dependent on sunlight to operate their solar cells and provide electricity. Also, it was important to know when it was light enough to take pictures or videos outside, along with many other tasks. It is also much colder during the Martian nighttime compared to the hours when the sun is up. If the scientists on Earth worked on local time, it wouldn’t correspond to time on Mars.

Some NASA scientists work and live on Martian time, an experience they found to be very disorienting and stressful. After just 18 days their noon comes at midnight, and soon they are having to sleep all day to get ready for their work sol. Perhaps it was easier for Mark Watney to adjust, considering all his clues for waking and sleeping were normal every sol. At any rate, worrying about how long his sol lasted was among the least of his concerns!

If you have any comments or questions about keeping time on Mars share your thoughts with us in the comment section and on Facebook or Twitter using #ACSChemClubBook.

Don’t forget, about the resource packet for the ChemClub Virtual Book Club, including the two contests that are still open:

 

The Martian Book versus Movie

While the ChemClub Virtual Book Club is about the printed version of The Martian, it would be hard to never mention the movie version. The movie gives the characters faces and voices making it more appealing to a wider audience. We’ll explore resources for both the film and the novel in this blog post, but remember to share your thoughts with us in the comment section and on Facebook or Twitter using #ACSChemClubBook. Continue reading The Martian Book versus Movie”

Science in Fiction

The Martian Header

I don’t even remember why I chose it to read. Maybe it was random buzz on the internet. I mainly needed something to kill time on a cross-country flight. On the plane, I cracked it open. Just a few pages in, I knew it was different. An interesting science fiction story, but it was something more that appealed. It was how science and problem solving were woven directly into the plot of The Martian at nearly every turn. Continue reading “Science in Fiction”

Fermi Questions: Back of the Envelope Calculations

The Art of Estimation
When I was in high school, in the days before electronic calculators were available, we learned how to use mechanical slide rules (see ChemMatters, April 2004, p.4) for our calculations. While they were great for getting a good answer to math problems, they didn’t keep track of the decimal place. That had to be done by keeping track of an order of magnitude estimate of the answer. Continue reading “Fermi Questions: Back of the Envelope Calculations”

The Martian Virtual Book Club Resources

The Virtual Book Club is officially live now! If you didn’t sign up before, you are still able to access and use all of the great resources we’ve created around Andy Weir’s The Martian! Check the blog each Thursday from now until May to follow our journey as we read the book, post background information about the activities and the book, and take a look at what the Clubs are sharing through #ACSChemClubBook.

ChemClubs who signed up for the Virtual Book Club, you’ll be receiving a packet soon with the guides and activities available below. There are two contests each with an opportunity to win a movie prize pack. Just share your photos, lists, calculations, etc. on Facebook, Instagram, or Twitter using #ACSChemClubBook, or send your responses to hschemclubs@acs.org.

Continue reading The Martian Virtual Book Club Resources”