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How to Create a Calendar for Mars

The red planet, Mars, has captivated the human imagination for centuries. Now it is the focus of science, as the European and American space agencies plan missions to our neighboring planet. Creating a Martian calendar is essential to mission planning; it is also an interesting science project for Earth-bound scholars. With an orbit of 1.52 Astronomical Units, half again as large as Earth's, the Martian year is longer -- about 687 Earth days -- but each day is nearly the same length as a day on Earth. Its axial tilt also gives Mars four seasons, much like Earth's.

Things You'll Need

Calendar
Ruler
Calculator
Paint or markers (optional)

Instructions

- 1
  Observe a conventional calendar. Normally, each page shows one month divided into seven-day weeks, based on cultural conventions. Decide which of these conventions you will adopt for your Mars calendar.
  
  Remember that all Earth's calendars are based on cultural and social traditions and expectations, and that these conventions do not really exist for a Martian calendar. That fact makes the decision-making part of this process more important than the execution, because you will need to decide whether to try to emulate Earth-standard seven-day weeks.
  
  Mars' two small moons, Deimos and Phobos, do not influence the Martian landscape as our larger, single moon affects Earthly tides, so the length and nature of the "months" will be part of the planning. Basing your calendar on the four recognizable seasons of Mars will give you more consistent points to date from than trying to copy Earth's lunar months.
- 2
  Measure a piece of paper and mark it off in even increments, based on the organizational scheme you choose. You will want your marks at least 3/4 inch apart; smaller divisions will make your calendar difficult to read.
- 3
  Lay the ruler along your marks and draw out a grid, using the ruler as a straight edge. Leave at least one empty "row" at the top of your paper for convenience of labeling. Depending on the size of grid you chose, using standard typing paper, you will have a grid of up to 11 squares across and up to 14 squares down.
- 4
  Repeat Steps 2 and 3 as needed on additional pages, until you have the number of grids you need for the plan you created in Step 1.
- 5
  Calculate your calendar divisions. The closest analogies to Earth's calendar on Mars are the nearly 24-hour day and the four seasons. The Martian year has 669 Martian days, or "sols." To come up with an even distribution of days and weeks, you'll need to incorporate at least one leap day each year. Dividing the year into four 167-day seasons will leave one leap day.
- 6
  Label the calendar based on the divisions you calculated. If you have chosen to keep the Earth convention of months, you may choose to keep the English names (with months about twice as long), or make up your own names.

Astronomy