Since the earliest times, the natural cycles of the Sun and Moon have been used to measure intervals of time. Solar cycles define days, years, and seasons while the Moon marks of months ("moonths").

There are two major lunar cycles, the best known being the 29 1/2-day synodic month during which the Moon goes from new Moon to new Moon. ("Synodic" refers to the meeting of the Sun and Moon). Less apparent is the 27 1/3-day sidereal month which is based on the Moon's position as seen against the background stars.

If Earth wasn't orbiting the Sun, synodic and sidereal months would be equal, but since we are moving, the synodic month takes longer. In a sidereal month, the Moon travels 360 degrees (one complete circle) around Earth before re-passing the same backgrounds stars. During this time, however, Earth has traveled nearly 1/12 of the way around the Sun, meaning the Moon must travel nearly 390 degrees, and two more days, before reaching the next new Moon.

A year being 365 1/4 days, there is not an even number of synodic or sidereal months in a year. This was not a problem for cultures who referred to these intervals by the names they gave full Moons, like Harvest, Hunter's, and Long Night Moon.

But when our ancestors devised formal calendars, adjustments were required, like adding or subtracting day and even ignoring periods of time. These months approximate but no long exactly correspond with the lunar cycles. The names we use for our months derive from the Romans and their Latin language.

Originally, the Roman year had 10 months that began with March, named for Mars, the god of war. The second month, April, was named for Aphrodite (Venus), the goddess of love and beauty. May is the month of Maia goddess of spring. June honors Juno, goddess of women, childbirth, and marriage.

July was originally called Quintilis (quintus being Latin for fifth) as the fifth month; it was renamed by Julius Caesar in 46 BCE to honor himself. Similarly, August, first known as Sextilis (sex=six) as the sixth month, was charged by Augustus Caesar.

The next four retained their Latin numeric names: September (septem = seven) as the seventh month, October (octo = eight) as the eighth month, November (novem = nine as the ninth month, and December (decem = ten) as the tenth month.

The winter months apparently went unnamed until about 700 BCE when the eleventh and twelfth months were added. January was named for Janus, the double-faced god of beginnings and endings who could see the past and the future. February came from Februa, the festival of purification.

So like the names we use for many constellations as well as the days of the week, the names of our months were invented by our ancient ancestors.

Sky Calendar

• February 28, Sunday evening: The full Moon is called Wolf Moon, Snow Moon, and Hunger Moon.

•March 1, Monday evening: The Moon is to the right of Saturn as they rise around 8:00 p.m.; following each other across the sky all night, by morning the Moon is to the lower left of the planet.

• March 7, Sunday: The Moon is at 3rd quarter.

• Naked-eye Planets. (The Sun, Moon and planets rise in the east and set in the west due to Earth's west-to-east rotation on its axis). Evening: Mars is prominent high in the east as Saturn rises some two hours after sunset. Morning: Saturn is in the west southwest.