How often would a lunar eclipse occur if the moon's orbit were not tilted?

Answer 1

They would occur one every lunar orbit, as another answerer said; but would only be observed from the equator. Interestingly, a solar eclipse would then also occur every lunar orbit, again observable at the equator.

If the lunar orbit WAS aligned with the earth's orbit around the sun, life on earth would be quite different, because of the effect on the tides.

Edit: Did you mean the moon's orbit, or the earth's orbit? The above comment would be true if the earth's axis of rotation was not tilted at 23 degrees, and the moon were to rotate about the earth's equatorial plane. Life then would be VERY different, because of the effect on seasonal variation in climate.

:Life on earth as we know it depends on so many factors that have to be in a very narrow range:
- The sun is just the correctly sized star
-The earth is just the right size to contain an atmosphere
-The earth is just the right distance form the sun to allow oceans of water to exist
- The earth is tilted at just the right angle to allow for variations in the season

If it were not for these factors, life would be very differnt.

Answer 2

moon orbits earth in 27.3 days or so. (wikipedia)
we rotate the sun in 365. (pretty well known fact =D)

thats 13.4 chances per year if the moon's orbit was straight horizontal or vertical around the earth. (right?)

dunno. either way... it depends on where you are on the planet (like this past lunar eclipse. europe probably didnt see it because of the time (rotation of the earth) and we cant change the fact that its on a tilted axis.

plus if it happens every single time we get a full moon, that kinda devalues it, doesnt it? i think its cooler if they only happen so often =)