 Welcome to Spotlight. I'm Liz Wade. And I'm Joshua Leo. Spotlight uses a special English method of broadcasting. It is easier for people to understand, no matter where in the world they live. The year was 1752. On Wednesday, September 2, the people of Britain went to sleep. When they woke up in the morning, the date was Thursday, September 14. That sounds like a mistake. The date should have been Thursday, September 3, not Thursday, September 14. But this story is true. The people of Britain went to sleep on September 2. When they woke up, the date was September 14. This strange date change was the result of a British Act of Parliament. This Act was called the British Calendar Act of 1751. Why did the British Parliament do this? In 1752, the official calendar of Britain was behind the official calendar of Europe by 11 days. So, in the United Kingdom, the date was September 2. But in Europe, it was September 13. A calendar is very important for measuring days and months, keeping religious holidays, and observing the seasons. Britain had been following an old version of the calendar. In 1752, they finally began to use the calendar accepted by the rest of the world. This helped them trade with other countries and celebrate religious holidays at the same time as the rest of Europe. Calendars are very complex. They depend on careful measuring, and they affect many parts of the world. Today's spotlight is on the history of the most used calendar in the world, the Gregorian calendar. Calendars are very important to people all around the world. Calendars help us remember religious events. They help to set times for farming and hunting. They help mark events from history. They mark events happening in the sky. They mark the passing of time from century to century. Some experts believe that the ancient Roman and Egyptian people were some of the first to use calendars. They created calendars almost 3,000 years ago. The Romans based their calendar on phases of the moon. That is, how the moon appeared. The moon goes through a cycle every 29 and a half days. It begins as a full moon. It slowly gets smaller and smaller. Then it begins to get larger and larger until it is again a full moon. For the Romans, a full moon was the beginning of a new month. But the Egyptians based their calendar on the sun. The sun follows a set path in the sky as the earth travels around it. There are no clear months. Instead, measuring time depends on the seasons and where the sun is located in the sky. A year counted using this method is called a solar year. Since the Roman kingdom was so large, the Roman calendar was the most popular. But until about 46 BC or about 2,000 years ago, the calendar was not well organized. At first, there were only 10 months on the calendar. Each month was named after a number. The year always began in March and ended in December. The Romans did not even count the months that we now call January and February. They were not considered a part of the year. But after time, one of the emperors did divide this uncounted time. He named it and began to count it on the calendar. So then the months named after numbers were not correct anymore. Calendar officials did not always follow the calendar rules carefully. Officials of the Roman government sometimes changed dates and lengths of months to stay in office longer. After some time, the official Roman calendar was in trouble. It did not even follow the seasons. Then the Roman emperor Julius Caesar took control. He designed an improved calendar. He changed and improved the calendar in three main ways. First, Julius based his calendar on the solar year, like the Egyptians. This was important because it established the official Roman year as 365 days. Second, Julius changed the date of the official beginning of the year from March to January 1. Third, Julius changed the lengths of the months to how we know them today. Most countries of the time began using this new calendar. It was called the Julian calendar. There was one other very important change in the Julian calendar. A solar year is 365 and one quarter days. Julius had to think of a way to count this part or quarter of a day. Julius added an extra day into the calendar year. He declared the extra day should be added only once every four years. This is something that we still do today. A year with an extra day is called a leap year. Today we add this extra day to the end of the month of February. The Julian calendar was a big improvement on earlier calendars. But calendars are very difficult to design. And the Julian calendar still had a few mistakes. The length of the Julian calendar year was 11 and a half minutes short. This sounds like only a small counting mistake. But after many years, this small counting mistake began to add up. Every 400 years, these 11 and a half minutes add up to just over three days. Around the year 1582, this began to cause a problem. In 1582, the official calendar was not correctly lined up with the seasons. It was about 10 days behind. Religious holidays like Easter did not happen during the right season. The Catholic religious leader, Pope Gregory XIII, decided to fix the mistake in the Julian calendar. Pope Gregory kept many parts of the Julian calendar. But he established new, more complex rules for the leap year. His new calendar was called the Gregorian calendar. It took a long time for people all over the world to accept the Gregorian calendar. But now it is the most common in almost every country. Some cultural and religious groups do use other calendars for special cultural or religious holidays. But for official records, most countries use the Gregorian calendar. But even this calendar is not perfect. The Gregorian calendar is 26 seconds short of a solar year. This means that every 3,300 years, the official calendar will be different from the solar calendar by one day. When this happens, the world will have to fix the calendar again. The writer and producer of this program was Liz Wade. The voices you heard were from the United States. You can find our programs on the internet at www.radioenglish.net. This program is called The History of the Calendar. You can also leave your comments on our website. And you can find us on Facebook. Just search for Spotlight Radio. We hope you can join us again for the next Spotlight Program. Goodbye.