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# When was January 1 chosen as the beginning of the year?

In Caesar's calendar modifications of 46 b.c.e., he decreed that the year would begin on January 1 instead of March 25, as it had in the past. At that time Caesar also designated number of days in each month, unchanged to the present day.

# Why were 10 days lost from the year in 1582?

In 46 b.c.e., Julius Caesar implemented the Julian calendar, which was 11 minutes longer than a solar year. By 1582, those 11 minutes each year had added up to 10 days. Pope Gregory XIII aligned the calendar with the solar year by declaring October 5,

Why do we have leap years?

We have leap years to keep the calendar accurate with respect to the solar year. It takes the Earth 365 days, 5 hours, 48 minutes, and 46 seconds— just under 365.25 days—to revolve around the sun. If there were no leap years, every 56 years the calendar would be two weeks behind. By adding one extra day every four years, the calendar stays accurate.

1582, to be October 15, 1582, in the Catholic regions of the world, thus correcting for the 10 lost days.

# What is the Gregorian calendar?

In addition to moving the calendar forward by 10 days in 1582, Pope Gregory XIII also corrected the error of the Julian calendar. He declared that years ending in "00" would not be leap years, except those divisible by 400 (such as the year 2000). The Julian calendar, with Pope Gregory's correction, is known as the Gregorian calendar, which most of us use today.

# When was the Gregorian calendar adopted in the United States?

Though Catholic countries switched to the Gregorian calendar in the sixteenth century, Protestant countries, such as England and its colonies, refused to switch from the Julian to the Gregorian calendar at that time. It wasn't until 1752 that Britain and its colonies, including the colonies that soon thereafter became the United States, switched to the Gregorian calendar. By that time, there was an 11-day difference in time, so September 3, 1752, became September 14, 1752.

# Is the Gregorian calendar accurate?

Almost! It is still 25 seconds longer than the solar year. Therefore, after about 3,320 years we will be a full day ahead of the solar year. The keepers of time will have to deal with this problem when the time comes.

# What type of calendar did the French use between 1793 and 1806?

In 1793, during the French Revolution, an entirely new calendar was established by the National Convention. The calendar was designed to help rid French society of its Christian influences. Within this new calendar there were 12 months, each consisting of three decades. Each decade was composed of 10 days. Five days (six during leap year) were added at the end of the year to add up to 365 (or 366) days. Napoleon reinstated the Gregorian calendar in 1806.

# What type of calendar was used in the Soviet Union between 1929 and 1940?

The Soviets created the Revolutionary calendar, which had 5 days in a week (four for work, the fifth as a day off) and six weeks in a month. Five days (six during leap year) were added at the end of the year to add up to 365 (or 366) days.

# Which celestial bodies are the days of the week named after?

The names of the days of the week come from Roman or Norse names for the planets:

 Day Celestial Body (Roman/Norse) Sunday Sun/Sol Monday Moon Tuesday Mars/Tui Wednesday Mercury/Woden Thursday Jupiter/Thor Friday Venus/Frygga Saturday Saturn

# When did the twenty-first century begin?

The twenty-first century began at 12:00 a.m. on January 1, 2001. Since the first century, which spanned the years 1 to 100, centuries have been counted beginning with the year ending in "01" rather than "00." For instance, the twentieth century consists of the years 1901 through 2000.

# How does the tilt of the Earth affect the seasons?

Since the Earth is tilted 23.5 degrees, the sun's rays hit the northern and southern hemispheres unequally. When the sun's rays hit one hemisphere directly, the other hemisphere receives diffused rays. The hemisphere that receives the direct rays of the sun experiences summer; the hemisphere that receives the diffused rays experiences winter. Thus, when it is summer in North America, it is winter in most of South America, and vice versa.

The ancient Mayans were fascinated with measuring time, and even their pyramids were constructed to mark the time of equinoxes. The pyramid of Chichen Itza cast a shadow that reached the snakehead (foreground) at equinox.

# Where on the planet is it light 24 hours a day in the summer?

In the extreme north and south parts of the Earth (north of 66.5 degrees north, and south of 66.5 degrees south latitudes) it is light 24 hours a day during the summer and dark 24 hours a day during the winter. Northern cities like Reykjavik, Iceland, and Murmansk, Russia, have nearly 24 hours of daylight for a short period of time during the summer months.

# What are the Tropics of Cancer and Capricorn?

The two Tropics are the lines of latitude where the sun is directly overhead on the summer solstices. The Tropic of Cancer is at 23.5 degrees north and passes through central Mexico, northern Africa, central India, and southern China. The Tropic of Capricorn is at 23.5 degrees south and passes through central Australia, southern Brazil, and southern Africa.

# What are the solstices?

There are two solstices—one on June 21 and the other on December 21. On June 21, the sun is directly above the Tropic of Cancer at noon and heralds the beginning of summer in the Northern Hemisphere and the beginning of winter in the Southern Hemisphere. On December 21, the sun is directly above the Tropic of Capricorn at noon and heralds the beginning of winter in the Northern Hemisphere and the beginning of summer in the Southern Hemisphere.

# Can you stand an egg on end only on the spring equinox?

It is a common legend that an egg can be balanced on its end only on the spring equinox (March 21). Actually, there's nothing magical about gravity on the spring equinox that would allow an egg to stand on end—it can happen at any time of the year with patience and perseverance.

# What are the equinoxes?

There are two equinoxes—one on March 21 and the other on September 21. On both equinoxes, the sun is directly over the equator. March 21 heralds the beginning of spring in the Northern Hemisphere and the beginning of fall in the Southern Hemisphere. September 21 heralds the beginning of fall in the Northern Hemisphere and the beginning of spring in the Southern Hemisphere.

# Where are the Arctic and Antarctic Circles?

The Arctic Circle is located at 66.5 degrees north of the equator and the Antarctic Circle is located at 66.5 degrees south of the equator. Areas north of the Arctic Circle and south of the Antarctic Circle have 24 hours of light during the summer and 24 hours of darkness during the winter.

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