Let's Celebrate New Year's Day

Let's Celebrate New Year's Day — page 3
HOW WE MEASURE TIME When people first began to make calendars they used some ideas based on science A day is the time it takes Earth to make one complete rotation about 24 hours A month is based on the time it takes the Moon to travel around Earth The word month comes from moon Each moon cycle is about 29 and 1 2 days A year is the time it takes Earth to travel around the sun Each year is about 365 days The summer solstice is the longest day of the year The winter solstice is the shortest On the spring and autumn equinoxes night and day are equal in length EARTH S SEASONS EQUINOX March 20 Spring begins SOLSTICE June 21 Summer begins Spring Winter Summer Autumn SOLSTICE December 21 Winter begins EQUINOX September 22 Autumn begins