Celebrating the new year on January 1 is a relatively recent phenomenon. The calendar as we know it today has evolved several times and months have gone by different names. On the early Roman calendar, March was the first month of the 10-month calendar. That is why the last four months of the year have prefixes that coordinate with the seventh (September), eighth (October), ninth (November), and tenth (December) numerals. King Numa Pompilius reformed the calendar around 700 BCE by adding the months of January and February to the original 10 months. But the calendar still required some additional tweaking to be more aligned with the seasons. In 46 B.C., Julius Caesar introduced a solar-based calendar that was an improvement on the ancient Roman one, which was lunar-based. During this time, the month of Quintilis was renamed July in honor of Julius Caesar and Sextilis was renamed August in honor of Augustus. Shortly after the introduction of the solar calendar, the beginning of the year was moved from March 1 to January 1.