Constitution Day marks September 17, 1787, when 39 delegates signed the U.S. Constitution at the Philadelphia Convention — the document that established the three branches of government, the Bill of Rights, and the framework that has governed the United States for more than 235 years. Find out today's date, current time, day of the week, week number, and more. Your complete date and time resource. Discover what we're celebrating today and explore today's special observances. 2026-09-17 - National Pawpaw Day, Constitution Day And Citizenship Day, National Monte Cristo Day, National Apple Dumpling Day, National Professional House Cleaners Day, and September 17 | Birthdays And Events. Details about today's date with count of days, weeks, and months, Sun and Moon cycles, Zodiac signs and holidays. This day honors the hard-working individuals who keep our homes sparkling clean. From mopping floors to dusting shelves, their work goes far beyond simple tasks. The meaning of DAY is the time of light between one night and the next. How to use day in a sentence. Find a complete list of today's holidays, unique celebrations, and fun ways to celebrate every day of the year. 1. Of or relating to the day. 2. Working during the day: the day nurse. 3. Occurring before nightfall: a day hike. A day is a 24-hour period, or the length of time it takes the Earth to rotate fully on its axis. There are 365 days in a year, and 31 days in the month of January. On average, this is 24 hours (86,400 seconds). As a day passes at a given location it experiences morning, afternoon, evening, and night. This daily cycle drives circadian rhythms in many organisms, which are vital to many life processes.