excerpt from

Mars Underground

by William K. Hartmann

1997

edited by Thomas Gangale

"Mars takes 670 sols, or Mars-days, to go around the sun."

"Summer comes in June in the northern hemisphere, and so on. Here in the southern hemisphere, we have summer in late December on the day of the solstice, like Australia."

"The two calendars are totally independent. A calendar is for the convenience of the people on the planet using it. A calendar is tailored to a planet. But we keep the number of the year the same as it is on Earth."

"With a seven-day week, we can have a perpetual calendar if each month has eight weeks. Every month starts on Sunday."

"Holidays are celebrated according to the schedule on Earth, where they originated. So we have Christmas when it's December twenty-fifth on Earth, which falls at various times here. That way we get to share all our holidays on Earth."