Does mars have equatorial seasons and leap years?
ANSWER from Karen Young on May 2, 2001:
Yes, Mars has seasons for the same reason Earth does. Mars' axis in inclined about 24 degrees to its plane of revolution around the sun. When the northern hemisphere is inclined toward the sun, it is northern hemisphere summer. When the southern hemisphere is inclined toward the sun, it is northern hemisphere winter (southern hemisphere summer).
Mars doesn't have leap years, but only because we don't yet have a calendar for Mars. The leap year on Earth is needed to make up for the fact that earth's year is not exactly 365 days long. It is almost 1/4 of a day longer. After four years that adds up to a full day--hence the extra day added each leap year. We periodically have to make adjustments to keep the calendar in step with the seasons, though, because the year is just a little shorter than 365.25 days.
The Martian year is 686.95 Earth days long. Since the Martian day is 24 hours 37.4 minutes long, that would make the Martian year 669.57 Martian days long. In other words, if we made our Mars calendar year 669 Martian days long, we would need to add 57 days every 100 years. If the year were exactly 669.5 days long, that would means every other year would be a leap year. However it is a little longer, so every so often we would have to add an extra leap year to keep the Martian calendar in step with the seasons.