Reference Site Map
Daylight Saving Time
History & Science of Time
Lesson Plans on Time
Local Time & Time Zones
Measuring Time - Clocks
Measuring Time - Sundials
Miscellaneous Sites on Time
The 10,000-Year Calendar! With this calendar you can view a month or year calendar for any year from 1 to 10000 A.D. Site provides an explanation on how to use the perpetual calendar, plus Free Calendars, Calendar Converter, Calendar Links, 100-Year Perpetual Calendar, and Download Center where you can download a printable copy of the 10,000-Year Calendar in the format of your choice.
Ancient Calendars - Aztec, Egyptian, and Sumerian Calendars - Stonehenge from Inventors.About.com. See also Other Ancient Calendars from Calendars through the Ages.
Aztec Calendar Wheels, Central America, 1000 BCE by Kate McCloskey, Smith College Museum of Ancient Inventions.
Babylonian Calendar from Calendars through the Ages.
Baha'i Calendar from Calendars through the Ages.
Balinese Calendars. Balinese use two calendar systems, the Hindu Çaka and their own Pawukon, from Calendars through the Ages.
Calendar from time and date.com. Create yearly calendar: Choose a Year and Country - includes Holidays and Observances for selected country. Or Create calendar by month.
Calendar from Wikipedia, the free encyclopedia.
Calendar 365. 365 days - a calendar at hand. Year calendars, Handy dates (Daylight Savings - Start times and dates for the next 15 years, Holidays for this year and the next 5 years, Leap years, Seasons - Meteorological Seasons Astrological Seasons for Northern and Southern Hemispheres, Week number), Moon phases (Current moon phases, Moon calendar, Moon phases), World Clock, Calculate (Period between two datess in number of years, months, days, hours, minutes, seconds).
The Calendar of Ancient Rome. Learn how the ancient Romans measured time with sundials, waterclocks and sand glasses.
Calendar Origins - Where did Calendars Begin? Modern calendar origins.
● Calendar Name Origins - Names of Months.
● Origin of Names of Days.
● Why Seven Days in a Week? By Peter Meyer.
● Our Seven-Day Week from Calendars through the Ages, including: What Is the Origin of the 7-Day Week? What Do the Names of the Days of the Week Mean? What Is the First Day of the Week?
Calendar Zone: Bring Order to Calendrical Chaos! Links to a wide variety of calendars, including shopping and advertising sites: Art, Celestial, Cultural, Daily, Event, Geographic, Historic, Holidays, Interactive, Misc. (includes: All the phases and eclipses of the Moon), Reference, Reform, Religious, Software, Traditional, Web, and Women.
Calendars and Their History by L. E. Doggett. Introduction, Astronomical Bases of Calendars, Calendar Reform and Accuracy, Historical Eras and Chronology, The Gregorian Calendar, The Hebrew Calendar, The Islamic Calendar, The Indian Calendar, The Chinese Calendar, The Julian Calendar.
Calendars through the Ages: Calendars from the Sky. Topics covered: Our 7-day week (origin and meaning of names of days of the week), Our year, Calendars (Christian, Jewish, Islamic, Chinese, Mayan, etc.) plus other unusual and interesting subjects relating to time and calendars.
Calendopaedia - THE Encyclopaedia of Calendars. Contents: Comparison of Calendars, Astronomical Calendar, Julian Calendar, Gregorian Calendar, Other Calendars, About Time, and Links to Other Sites. Includes a Complete Index of the Site.
Chambers's Book of Days from University of Wisconsin-Madison Libraries. A Miscellany of Popular Antiquities in connection with the Calendar an electronic reprint of the original: Chambers's Book of Days. Philadelphia: J. B. Lippincott & Co., 1879.
Chinese Calendar from Party Guide Online. Includes Western-Chinese Calendar Converter, World Calendar - convert to several other calendars showing holidays, Lunar calendar, Make Your Own Chinese Calendar - outputs Chinese dates (in Chinese) into a Gregorian-style calendar, Chinese fortune calendar, Description of the Chinese calendar, Mathematics of the Chinese calendar, Solar Terms and the Chinese calendar, 60-year cycle (1957-2017), Previous 60-year cycle (1897-1957) including details from Year of the Rooster to Year of the Monkey.
Chinese Calendar from Wikipedia, the free encyclopedia.
The Chinese Calendar. History and information from Calendars through the Ages.
Chinese Calendar - Introduction. Printable Chinese monthly calendar with lunar calendar dates, in PDF. See also The 12 Animals of the Chinese Calendar: Rat Ox Tiger Hare Dragon Snake Horse Sheep Monkey Rooster Dog Boar, Chinese New Year, Chinese Animal Zodiac with background information and legend about the twelve animals.
The Chinese Calendar. Learn how the ancient Chinese calculated time using the sun, the moon, and oracle bones. Years were also counted from a succession of eras established by reigning emperors.
Chinese Lunar Calendar. Background and concept of the Chinese calendar from Chinese Zodiac Page. "In traditional China, dating methods were cyclical. ... A popular folk method which reflected this cyclical method of recording years are the Twelve Animal Signs. Every year is assigned an animal name or 'sign' according to a repeating cycle."
Chinese New Year by the Chinese Calendar. There are 3 ways to name a Chinese year: By an animal, By its Formal Name (Stem-Branch), or By current year (e.g. 2007 = Year 4704 by the Chinese Calendar).
Chinese Zodiac Sign Calculator. Each year of the Chinese calendar is associated with one of the twelve animals of the Chinese Zodiac. Use the form provided to determine the Chinese Zodiac animal for your birth date. Check each Zodiac animal to see your Personality, Health, Career, Relationships, and Compatibility with other animal signs. The 12 Zodiac signs: Rat, Ox, Tiger, Rabbit, Dragon, Snake, Horse, Goat, Monkey, Rooster, Dog, Pig.
The Christian Calendar from Calendars through the Ages.
Create Calendar for Any Year. Choose a year and a country. Results will show phases of the moon, Holidays and Observances for that country, with option to customize your display.
The Curious History of the Gregorian Calendar - Eleven days that never were by Ben Snowden.
Dating - Calender Years. 1752 was the first year in England to officially begin on 1 January. Until the Calendar Act of 1752, the year in England began officially on 25 March (Lady Day), and not 1 January.
Early Roman Calendar from Calendars through the Ages.
The Egyptian Calendar from Calendars through the Ages.
Ethiopian Calendar from Calendars through the Ages.
Free Printable Calendar Templates. Create free printable calendars that are formatted for Microsoft Word®.
Free Printable Calendars. Free calendars from Printfree.com. Print monthly or yearly calendars.
The French Revolutionary Calendar (or Republican Calendar) from Calendars through the Ages.
Frequently Asked Questions about Calendars. Site answers many FAQ about the calendar, e.g. How does one count years? What is the Roman calendar? How did the Romans number days? What does an Islamic year look like? What is the origin of the 7-day week? What is the Long Count in the Mayan Calendar? Did the Mayas think a year was 365 days?
Future Calendars from Calendars through the Ages.
Gregorian calendar from Wikipedia, the free encyclopedia. The Gregorian calendar or New Style calendar is a 12-month calendar first proposed by the Calabrian doctor Aloysius Lilius to replace the less precise Old Style Julian calendar. Decreed by Pope Gregory XIII on 24 February 1582, the Gregorian calendar is the solar calendar now in use worldwide.
The Indian Calendar from Calendars through the Ages.
The Islamic Calendar. Includes: Rules for the Islamic Calendar in Different Countries. See also The Islamic Calendar from Calendars through the Ages.
The Jewish Calendar from Calendars through the Ages. See also Jewish Calendar Conversions in One Step, Jewish Calendar Description by Stephen P. Morse.
Julian calendar or Old Style calendar from Wikipedia, the free encyclopedia. "The Julian calendar, a reform of the Roman calendar, was introduced by Julius Caesar in 46 BC, and came into force in 45 BC."
The Mathematics of the Chinese Calendar by Helmer Aslaksen, Department of Mathematics, National University of Singapore.
The Mayan Calendar. History and information from Calendars through the Ages.
Other Ancient Calendars include Babylonian calendar, and Egyptian calendar.
Perpetual Calendar from Infoplease. View any month, any year, in the Gregorian calendar. Enter any year, past or future. Click any day for more information: Equivalent date in Hebrew calendar, Chinese calendar and Islamic calendar, plus This Date in History citing major world events that occurred on this date.
Persian Calendar (Iran) from Calendars through the Ages.
Printable Calendars. Free calendars from Printfree.com. Print monthly or yearly calendars. Free Printable Calendar Templates from printablecalendar.ca. Free Printable Calendars from Vertex42.com. Free Printable Yearly Calendars.Free printable calendar 2009, 2010, 2011, 2012 from Calenweb.com.
Roman Calendar - Early Roman Calendar. History and information from Calendars through the Ages.
The Shire Calendar. "The calendar used by the Hobbits of the Shire divided the year into twelve months which, unlike the irregular months of Roman and modern Europe, were of equal length: every month in the Hobbit year had exactly thirty days."
Timeline of Interesting Calendar Facts from Calendars through the Ages.
Western-Chinese Calendar Converter. Convert between Solar and Lunar Calendars.
Daylight Saving Time. Learn about history of daylight saving, standardization of time, and when regions around the globe spring ahead and fall back, from WebExhibits.org.
Daylight saving time from Wikipedia, the free encyclopedia.
Daylight Saving Time Around the World 2007 from Time and Date.
Daylight Saving Time Help and Support Center from Microsoft.com. Daylight Saving Time Update Guide will help you make sure that your computer is updated for the new daylight saving time.
Daylight Saving Time in Canada. In 2007, Daylight Saving Time begins on the second Sunday in March and ends on the first Sunday in November. This pattern will be followed by all provinces which observe daylight saving time and each province has amended their legislation to reflect this change. (Previously, Canada had observed Daylight Saving Time from the first Sunday in April until the last Sunday in October). This change in Daylight Saving Time will keep Canada's Daylight Saving Time pattern consistent with the United States.
Daylight Time. When does Daylight Time begin and end in the United States? Starting in 2007, daylight time begins in the United States on the second Sunday in March and ends on the first Sunday in November. On the second Sunday in March, clocks are set ahead one hour at 2:00 a.m. local standard time, which becomes 3:00 a.m. local daylight time. On the first Sunday in November, clocks are set back one hour at 2:00 a.m. local daylight time, which becomes 1:00 a.m. local standard time. Not all places in the U.S. observe daylight time, e.g. Arizona, Hawaii, and most of Indiana do not use it. Site includes a link to Energy Policy Act of 2005.
Saving Time, Saving Energy. Daylight Saving Time, Its History and Why We Use It by Bob Aldrich, California Energy Commission. Includes a Daylight Saving Time In the United States, 1990 Through 2015. In spring, move clocks forward one hour. In fall, turn clocks backward one hour.
A Brief History of Time. YouTube video, 2 hrs. 48 min. 38 sec. "A Brief History of Time (subtitled "From the Big Bang to Black Holes") is a popular-science book written by British physicist Stephen Hawking and first published by the Bantam Dell Publishing Group in 1988." ~ Wikipedia. Sound of Full Book. Explaining 14 billion years of existence in less than 3 hours.
An entire history of time measurement in six minutes. YouTube video, 6:38 min. Discussion on the history of time measurement in the world and how it preceded every major thought revolution in physics.
Geological history of Earth from Wikipedia. Science Engineering and Technology Timeline from Intute - predecessor sites (EEVL, GEsource and PSIgate) together make up Intute. Web Geological Time Machine and History of Geologic Time Scale. The Geologic Time Scale in Historical Perspective from University of California Museum of Paleontology (UCMP). What do the divisions of the geologic time scale signify?
A Guide to Metric Time or Decimalized Time. Metric Time (MT) is an attempt to create a decimalized time system for our modern base-10 using world.
History of Telling Time - A brief history of time. Talking Clock - Clock shows exact time as of now; click to hear what time it is. (Be patient, slow loading as it figures out where you are in the world). Timeline of Time, Types of Clocks - Sun clocks, Water clocks, Mechanical clocks, Quartz Clocks, Atomic Clocks, Time Zone Information, United States Time Zones, Map of World Time Zones, Telling Time Games & Quizzes, Interactive Teaching Clock, Printable Paper Clock, Telling Time Activities: How old are you in weeks, hours, minutes, seconds? How far away is your next birthday? Time Glossary, plus Lessons and Worksheets for Teachers.
History of Time Measurement. YouTube video, 8:21 min. Dr. Benjamin Baker and Chantal Klingbeil discuss the manner in which time has been measured throughout history. What people have used through history to measure time: water, candle, sundials, sun, stars, mechanical clocks, atomic clocks, etc.
Horologium: Calculating the Hours in Ancient Rome. How the Romans measured time: Hours, Days, Seasons (Winter Solstice and Summer Solstice).
Horology from Wikipedia, the free encyclopedia. Horology is the study of the science and art of timekeeping devices. Clocks, watches, and marine chronometers are examples of instruments used to measure time.
Horology is the Science of Time, Timekeepers (Clocks, Watches) and Timekeeping. Internet Resources on Time Synchronization and Time Standards. (Unfortunately, site has many deadlinks).
Hour from Wikipedia, the free encyclopedia. Definition: In modern usage, an hour is a unit of time 60 minutes, or 3,600 seconds in length. History. Different ways of counting hours.
How Time Works. Time cannot be seen or sensed. It just happens. Human beings have therefore created ways to measure time that are totally arbitrary. Topics include time's origins, some common time spans, clocks, time zones, daylight-saving time, calendar, B.C. and A.D.
Intellectual history of time from Wikipedia, the free encyclopedia.
Measuring Time. YouTube video, 2:49 min. A short video that provides a brief overview of man's quest to develop new and better ways to measure time. An excerpt from documentary "Time Travel - Journeys into Time" written and hosted by American physicist, Dr. David Lewis Anderson.
Sir Sandford Fleming (1827-1915) - Father of Standard Time. Standard Time was invented by Scottish Canadian, Sir Sandford Fleming in 1878. Article by Mary Bellis, an inventor. From Inventors.About.com.
Space-Time and the Speed of Light | Einstein's Relativity. YouTube video, 5:43 min. "In physics, spacetime (or space-time) is any mathematical model that combines space and time into a single continuum. Spacetime is usually interpreted with space being three-dimensional and time playing the role of a fourth dimension that is of a different sort from the spatial dimensions."
Telling Time. How humans measure time has changed dramatically through the ages. The Franklin Institute Online offers many links to sites dealing with time.
Telling Time and the Age of the Universe by David C. Black, Director of Lunar and Planetary Institute (LPI). "It is the issue of age, and how we determine the passage of time, that is the subject of this article." See also How Old Is the Universe? "Until recently, astronomers estimated that the Big Bang occurred between 12 and 14 billion years ago. To put this in perspective, the Solar System is thought to be 4.5 billion years old and humans have existed as a genus for only a few million years. Astronomers estimate the age of the universe in two ways: 1) by looking for the oldest stars; and 2) by measuring the rate of expansion of the universe and extrapolating back to the Big Bang . . ."
Time from ThinkQuest Library of Entries - The Sun: Man's Friend and Foe. A brief discussion on time and the sun with reference to the Cheops Pyramid thought to be a huge stone calendar, and the Mayan calendar which predicted eclipses and accurately marked the position of the sun years in advance.
Time from Wikipedia, the free encyclopedia. Time Measurement: history & devices, Definitions and standards: World time, Sidereal time, Chronology, Time in religion and mythology, Linear and cyclical time, Time in philosophy, Time as "unreal", Nature of time in physical sciences, Time in classical mechanics, Time in modern physics, Spacetime, Time dilation, Arrow of time, Quantised time, Time and the Big Bang, Time travel in science fiction, Use of time, and more.
A Walk through Time. The Evolution of Time Measurement. Topics covered: Ancient Calendars, Early Clocks, Revolution in Timekeeping, The "Atomic Age", World Time, Scales, National Institute of Standards and Technology (NIST) Time Calibration.
The History of Leap Year - Who Invented Leap Year? From Mary Bellis, About.com.
Leap year from Wikipedia, the free encyclopedia.
Leap Year. A leap year is a year in which an extra day in added to the calendar in order to synchronize it with the seasons. Find out more about the Leap Year, from Eric Weisstein's World of Astronomy.
Leap Year as explained by Newton, Ask a Scientist, from Forest Preserve District of Cook County (Illinois).
Leap Year. Fun facts from Care2.com. History of Leap Year. February 29th is also known as Sadie Hawkins Day. Developed out of the popular cartoon strip "Li' Abner" by Al Capp, when unmarried women could run after unmarried men to propose on Sadie Hawkins Day. The tradition actually started with St. Patrick and St. Bridget (5th Century) in Ireland.
Leap Year Calculator from Online Conversion.
Leap Year Traditions from Sheri & Bob Stritof, About.com. Leap Year has been the traditional time that women can propose marriage. St. Bridget's Complaint - It is believed this tradition was started in 5th century Ireland when St. Bridget complained to St. Patrick about women having to wait for so long for a man to propose.
Leap Year Rules from Western Washington University (WWU) Planetarium. Leap Year Explained from infoplease.
Leap Years & Leap Seconds from NIST Time and Frequency FAQ. What is a leap year? What is a leap second? Why do we need leap seconds?
Roman Calendar - Why 28 days in February?
Why are leap years used? From time and date.com.
Eyes on the Sky, Feet on the Ground: Chapter Three - Time and the Calendar from Harvard-Smithsonian Center for Astrophysics. Discussions to follow student activities. Materials listed, how-to-make directions provided.
● Topic 1 - Recording the Passage of Time Activities: How to make Hour Glass or Sand Clock, Water Clock, Candle Clock, Atomic Clock.
● Topic 2 - Time Zones Activities: What Time Is It? Daylight Saving Time.
● Topic 3 - The Moon: A Natural Calendar Activities: Make a Lunar Calendar.
● Topic 4 - The Zodiac Activities: Sun's Yearly Trip Though the Zodiac, Hi! What's Your Sign? Precession of the Earth's Axis.
● Topic 5 - The History of the Calendar Activities: Exploring the Calendar, Make Personalized Calendars.
● Topic 6 - Future Calendars Activity: Invent a New Calendar.
12-hour clock from Wikipedia, the free encyclopedia. The Latin abbreviations "a.m." and "p.m." (often written "am" and "pm"; "AM" and "PM"; and "A.M." and "P.M.") are used in English and Spanish ... In the United States ... since the 1980s, noon is often called 12:00 p.m. and midnight 12:00 a.m., as at the beginning of a day ... but there is sufficient confusion over these uses to make it advisable to use 12 noon and 12 midnight where clarity is required.
Any Time, Anywhere. Correct, current, local time from World Time Server. Check out Time Converter. Set a time from your choice of location to see what time it is at another location in the world.
Clock live: Right now ... the official U.S. time is: - The Official U.S. Time for all states. Click on a time zone across a map of the United States, site will instantly provide you with today's date, the current time ticking away, and accurate within 0.3 seconds. Includes links to Time Exhibits.
Frequently Asked Questions (FAQ) from National Institute of Standards and Technology (NIST), Time and Frequency Division. Are noon and midnight 12 a.m. or 12 p.m.? Why is UTC used as the acronym for Coordinated Universal Time? What is a Modified Julian Date (MJD)?
Local Times Around the World. First, select a continent or region: Africa, America, Antarctica, Asia, Atlantic, Australia, Europe, or Pacific. Then choose a country and a location to view details.
Military/NATO/Letter Time Zones. Z - Zulu time - Zero meridian time.
The MightyCool Atomic Clock. See the current time, reload to see it again.
● PST = Pacific Standard Time (Coordinated Universal Time minus 8 hours, e.g. Los Angeles, Vancouver)
● MST = Mountain Standard Time (UTC-7 hours, e.g. Salt Lake City, Edmonton)
● CST = Central Standard Time (UTC-6 hours, e.g. Chicago, Winnipeg)
● EST = Eastern Standard Time (UTC-5 hours, e.g. New York, Toronto)
● UTC = Coordinated Universal Time, or Greenwich Mean Time, or Zero meridian time, or Zulu time.
The Official U.S. Time Clock. Right now, the official U.S. Time is ... time in hours, minutes, seconds, plus today's date, accurate within 0.2 seconds. Click to change time zone.
Offset Time Zones by Matt Rosenberg, a professional geographer. Many places in the world use offset time zones. These time zones are offset by a half-hour or even fifteen minutes off of the standard twenty four time zones of the world.
Time and Frequency Division of the National Institute of Standards and Technology (NIST). Find the Official United States Time. You can set your computer clock to the correct time right now by using the Internet or the Telephone.
Time Genie. What Is the Current World Time? Select a location to see the current time, today's date, time zone, Standard Time difference compared to UTC/GMT, Daylight Saving Time if applicable, Latitude, Longitude, 4 digit city code, e.g. cyyz for Toronto, Canada, plus flag of the country.
● Your Clock allows you to compare up to 14 different times around the world.
● Future Time allows you to determine what time it will be in various locations at a time in the future.
● Time Zone Abbreviations.
● World Time gives you the Current Time for 133 Cities Around the World.
● Random Time gives you the Current Time for 150 World Cities, and each time this page is reloaded, 150 cities, towns or villages will appear in a random fashion.
Time in Canada from Wikipedia, the free encyclopedia. Zones: Pacific Standard Time, Mountain Standard Time, Central Standard Time, Eastern Standard Time, Atlantic Standard Time, Newfoundland Standard Time, Daylight saving time, TZ zones.
Time Zone Abbreviations from Time and Date.com. Includes Time zone tools and information, Calendars, holidays and date calculators, Calendars and Countdown counters.Standard abbreviations:
Time Zone Converter. Indicates the current time as you access the site. Apart from allowing you to convert time zones in current time, amazingly, this site allows you to specify a given date and time to convert past or future times. Select a location "From Time Zone" and convert "To Time Zone" of another location.
Time Zones in Australia.
Time Zones in Europe.
Time Zones in North America.
US Naval Observatory Master Clock Time.
What Time Is It?. See clock display of time right now where you are. USNO Time in Standard Time Zones. USNO Master Clock Animated GIF Clocks: Universal Time GIF Clock (require Netscape).
Why Has Date Changed for Start of Spring? By Joe Rao, Space.com. The first day of spring no longer falls on March 21. In 2008, spring season starts one day earlier on March 20 in all time zones in North America. In the years 2008 and 2012, those living in Alaska, Hawaii and the Pacific, Mountain and Central time zones will see spring begin even earlier: on March 19. And in 2016, it will start on March 19 for the entire United States (and most likely for Canada as well).
The World Clock - Time Zones - Current Local Times Around the World. You can sort the list of cities around the globe by City, by Country, or by Time Zones. Includes links to Countdown to New Year, Time Zone abbreviations, Generate a Calendar of any Year of your choice, and more.
World Time - 36 time zones at a glance. See also Countries and Time Zones and Astronomical Background. Available in German and English.
World Time Server.com. Find current time and date anywhere in the world. Search a location by country or by major city.
The World's Time Zones from Inventors.About.com.
Antique Clock Types: An Illustrated Glossary: 44 categories of clock types. History of Antique Clocks and Their Makers. A Brief History of Antique Clocks. Clock History and Education Links. Clock Repair and Care Links. Clock Parts, Tools and Supplies Links from Antique Clocks Price Guide.
Antique Clocks Identification and Price Guide OnlineOnline database shows 9,832 antique clocks with 17,100 color photos. Descriptions and "real world" values show actual auction and retail prices. American, English and European clocks of all types. Extensive index. Search by manufacturer, type or key word.
Astrolabe from Wikipedia, the free encyclopedia.
The Astrolabe: An Instrument with a Past and a Future. The astrolabe is a very ancient astronomical computer for solving problems relating to time and the position of the sun and stars in the sky. Includes history, typical uses, and collections of Astrolabes. See also Front and back views of an ancient Arab astrolabe.
Astronomical clock from Wikipedia, the free encyclopedia.
At Home Astronomy: Making a Simple Astrolabe, Using a Simple Astrolabe
Atomic Clock. YouTube video, 2:27 min. From Russia: "The accuracy of time measurement is one of the major problems throughout the whole history of mankind. As the technology developed, the requirements for clock accuracy grew. Clocks have passed a long way of evolution: sundial, water, sand, mechanical, quartz, and finally, atomic. Atomic, or as it is sometimes called molecular or quantum, clock is a device for measuring time, which uses the natural oscillations of atoms or molecules as a batch process. Atomic clocks have the greatest importance for navigation. Determining positions of spacecrafts, satellites, ballistic missiles, aircrafts, submarines, and vehicular traffic in an automatic mode using satellite communication (GPS, GLONASS) are unthinkable without the atomic clock."
Atomic ticker clocks up 50 years from BBC News. The first atomic clock, which uses the resonance frequencies of atoms to keep extremely precise time, was developed by Dr Louis Essen at UK's National Physical Laboratory in 1953. By 1964, Essen had reduced the timekeeping errors from one second in 300 years to about one second in 2000 years. See also biography of Louis Essen and Atomic clock from Wikipedia, the free encyclopedia.
Brief History of Atomic Clocks at NIST. Timeline of Atomic Clock History at National Institute of Standards and Technology.
A Brief History of Clocks: From Thales to Ptolemy. Includes illustrations of clocks where available. Information geared to more advanced students. See also A Brief History of Clocks by Mystical World Wide Web, UK.
Cesium Fountain Atomic Clock - The Primary Time and Frequency Standard for the United States. From Inventors.About.com.
Clock from Wikipedia, the free encyclopedia. Contents include: History (Water clocks, Early mechanical clocks, Early astronomical clocks), Types of Clocks (Analog clocks, Digital clocks, Auditory clocks, Timekeeping methods), Purposes of Clocks (Ideal clocks, Navigation), Specific types of clocks (Alarm clock, Atomic clock, Balloon clock, Cuckoo clock, Hourglass, Japanese clock, Lantern clock, Pendulum clock, Railroad chronometers, Skeleton clock, Stopwatch, Sundial, Tide clock, Watch, Water clock, and many more).
Clock History: An Introduction from Mystical World Wide Web. Contents include: Ancient Calendars, Clocks, Sun Clocks, Water Clocks, Europe & Clocks, Mechanical Clocks, Quartz Clocks, Atomic Clocks, and Time Out.
Clocks by Ellie Crystal. Illustrated. Article covers history of clocks - Sumerians were one of the first ancient people to use sundials by dividing the day into 12 parts and each part about 2 hours long, Egyptians also divided the day into 12 parts and used huge granite columns called Cleopatra Needles (obelisks) to keep track of time periods, Early water clock, Su Sung water clock tower, Hour glass, Modern clocks, Pendulum clocks, Quartz clock, Atomic clocks, Candle was once used as an 'Alarm Clock', and other interesting information.
Clocks and Calendar History by Mary Bellis, an inventor. From Inventors.About.com.
Clocks and Watches - Images from New York Public Library Digital Gallery. Images may be enlarged for viewing.
Clocks ... Teaching Time. Contents: Escape into Time - The Franklin Institute Timepieces Collection (Empress Josephine Clock, Escapements, Fels Clocks, Foucault Pendulum, Frick Electric Program Clock, Seth Thomas Calendar Clock, Sundials, and Synchronome Clock), Tracking Time Projects (Community of Clocks, Millennium Clock Project), The Hands of Time Activities for Students, Measuring Time Lesson Plans for Teachers, plus Elements of Time Vocabulary and Book Lists.
Clockworks: From Sundials to the Atomic Second. Measuring Time from Britannica.com. An amazing site. Provides animated illustrations, history, description, other interesting information, and movie (choice of normal speed or rapid speed movie where applicable) of each time measuring device: Sundial, Clepsydra, Astrolabe, Candle Clock, Sandglass, Weight-Driven Clock, Spring-Driven Clock, Pendulum Clock, Quartz Watch, and a Cesium Atomic Clock. Text version available for those unable to access the graphics version (Shockwave required).
The Canadian Clock Museum Virtual Tour. View images of Midgets Palace "grandfather" clock, Woodstock model (1 of 7 wall clocks made by Arthur Pequegnat Clock Company), a unique animated grandfather clock made in 1980s by Canadian craftsman Werner Friedrich, examples of Seth Thomas (Plymouth Hollow, Connecticut) 30-hour and 8-day clocks sold door-to-door in Canada West in the 1850s-1860s by various clock pedlars, and many other unusual clocks.
The Development of the Clock and the Concept of Time in the Middle Ages . Examples of some clocks and time keeping instruments typical of the Middle Ages, e.g. Pocket dial, Astrolabe, and Water clock. See also the making of a Canterbury Dial and other Replica Instruments including an automatic water clock.
Exact Time. Click here to see this very instant the exact time on the US Naval Observatory Master Clock. See also exact Universal Time, Eastern Standard Time, Central Standard Time, Mountain Standard Time, Pacific Standard Time, Alaska Standard Time, and Hawaii-Aleutian Standard Time.
Galileo: The Best Atomic Clock in Space. YouTube video, 2:55 min. How the Galileo Atomic Clocks Work. "The Galileo satellites will carry two types of clocks: rubidium atomic frequency standards and passive hydrogen masers. The stability of the rubidium clock is so good that it would lose only three seconds in one million years, while the passive hydrogen maser is even more stable and it would lose only one second in three million years."
Hourglass from Wikipedia, the free encyclopedia.
The Hourglass: How Father Time Got His Hour-Glass. Article briefly covers: clepsydra, sand glass, hourglass, water clock, sand clock, How old is the sand-glass? half-hour glass, burning knotted ropes, candle clock, sundial.
How an atomic clock works, and its use in the global positioning system (GPS). YouTube video, 4:33 min. "Bill shows the world's smallest atomic clock and then describes how the first one made in the 1950s worked. He describes in detail the use of cesium vapor to create a feedback or control loop to control a quartz oscillator. He highlights the importance of atomic team by describing briefly how a GPS receiver uses four satellites to find its position."
How Atomic Clocks Work from howstuffworks. How is Atomic Time Measured? Are Atomic Clocks Radioactive? What Are the Types of Atomic Clocks? How Does a Practical Cesium Atomic Clock Work? and When Was the Atomic Clock Invented?
How Digital Clocks Work from howstuffworks. Introduction, The Basics, High-Level View, Building Your Own Digital Clock, Circuit Diagram, 7490 Pinout, Creating the Second Hand, Displaying the Time as Numerals.
How Humans Kept Time with a History of Clocks from About Clocks.org.
How Pendulum Clocks Work from howstuffworks. Pendulum clocks have been used to keep time since 1656. Find out how a pendulum clock works, as well as the difference between a weight-driven and a spring-driven clock in the Q & A section.
How Quartz Watches Work from howstuffworks. Introduction, Before Quartz, The Quartz Crystal.
How to Build a Grandfather Clock by Brian Adler, eHow. How to Make a Grandfather Clock Chime from eHow.
How to Build a Water Clock from eHow. How to Make a Simple Water Clock from eHow. How to Make an Ancient Egyptian Water Clock from eHow.
How to Construct a Sand Clock by Alicia Bodine, eHow.
How to Make Miniature Wooden Clocks by Karen Frisch, eHow.
How to Read a Clock with Hands by jeansmith99, eHow. How to Read a Clock With 3 Hands by Justin Wash, eHow.
Invention of Clocks: Sun Clocks, Water Clocks, Obelisks - Egyptian shadow clock, Mechanical Pendulum Clocks and Quartz Clocks, Atomic Clocks and Time Standards from Inventors.About.com.
The Leicester Time Trail by Allan Mills. Illustrated. Contents: Astronomical Background, Sundials, Water Clocks, Modern Sundials, Sandglass and Candle Clock, Mechanical Clocks - Verge-and foliot clocks, Pendulum clocks, Automaton clocks, Public clocks, Domestic clocks, Moon dial, and Astronomical clocks.
Marc Tovar's Wooden ClockWorks. Lots of excellent illustrations of wooden clock plans designed for the scroll saw. Patterns are drawn on TurboCad and are very accurate.
Measuring time by setting fire to various things.
Time, Clocks and Gears. YouTube video, 8:50 min. "This video resource is designed to support the teaching of gears at an introductory level by explaining the role that gears play in mechanical clocks. Tower clocks, like Big Ben, use an elaborate set of gears to display time. The video includes information about Foliot and Pendulum clock mechanisms."
Visualizing Video Streams Using Sand Glass Metaphor by Edward Chang and Yung-Hsiang Lu, Stanford University. Includes illustrations of a 1896 Clog Almanac with the times of the season changes carved on it, Chinese Water Clock, Candle Clock, Coiled Clock, Insense Clock, Sand Clock, Magic Sand Glass, and more.
Water clock from Wikipedia, the free encyclopedia.
Chaldean Sundial, Greece, 320 BCE by Allison Crawford and Lei Liu, Smith College Museum of Ancient Inventions.
How to Make a Sundial from eHow.
How to make a sundial. YouTube video, 3:42 min.
Six sundial projects for you to make from Sundials on the Internet, UK.
Sundial from Wikipedia, the free encyclopedia.
Sundials and Latitude. YouTube video, 5:30 min.
Sundials on the Internet
practical information. Site helps you understand how sundials work, the many different varieties of sundials, with some simple projects to start you off making them.
● Sundials on the Internet. Contents include:
● An introduction to sundials and how they work
● Six sundial projects for you to make
● How to set up a horizontal sundial
● Pictures and descriptions of new public sundials from all over the world
● The many different types of sundials
● The Leicester Time Trail by Allan Mills with illustrations: Astronomical Background, Sundials, Water Clocks, Modern Sundials.
Solar Noon Calendar. Print Your Solar Noon Calendar wherever you are in the world. Site provides you with a table showing the exact time of solar noon for your exact location for each day of the year, enabling you to set up your sundial with accuracy.
Sundial from Wikipedia, the free encyclopedia.
The Sundial, How Sundials Work, Building a Simple Sundial, Sundial Construction (in PDF) from Goddard Space Flight Center, NASA.
Sunshine in Your Pocket! Making a sundial for the Northern hemisphere. Choose a level on how to make your own horizontal sundial: Advanced, Intermediate, or Novice. If you are not comfortable using a protractor and are not familiar with the trig functions sine and tangent, you can start at the Novice level. Excellent Website.
History of Measurement: Units of Time and Angle from Wikipedia, the free encyclopedia. "We can trace the division of the circle into 360 degrees and the day into hours, minutes, and seconds to the Babylonians who had sexagesimal system of numbers. The 360 degrees may have been related to a year of 360 days."
How time works from howstuffworks. Contents: Introduction to How Time Works, Time's Origins, Clocks, Time Zones, Daylight-saving Time, The Calendar: Years, Months, B.C. and A.D., plus related articles:
● How Pendulum Clocks Work
● How Digital Clocks Work
● How Quartz Watches Work
● How Atomic Clocks Work
● How Time Travel Works, plus links to:
● Time and Date.com
● World Time Server
● The World Clock - Time Zones
● U.S. Naval Observatory: World Time Zones.
International Atomic Time (TAI) from Wikipedia, the free encyclopedia. "TAI" from the French name Temps Atomique International.
A Matter of Time by Ken Tapping.
Mr. Dowling's Electronic Passport: Time and Space. Daylight Saving Time, Measuring Time, Years, plus A Look at the Stars, Aristotle's Conclusion, Copernicus, Galileo's Observations, Isaac Newton and Gravity, Longitude and Latitude, Seasons, Map Projections, and more.
Once Upon A Time Slideshows. Journey through Time and discover how telling time evolved from ancient civilizations to the present. Topics covered: Calendar, Seasons, Measuring Time (Day, Hours, Months, Seconds, Years, Daylight Saving Time, and Timepieces). Includes Interactive Classroom Activities.
Telling Time Without a Clock: Scandinavian Daymarks. Pointing at the Sun, Hours of Day, Hours of Night, Scandinavian Daymarks, Midday Daymark, Other Daymarks, Daymarks and Day Sections Among Other Peoples, How Daymarks Work, Class Projects: Schoolyard Daymarks and Classroom Noon-Line Project.
Time & Timekeeping Fact Files from National Maritime Museum, Royal Observatory Greenwich. Contents include: What Is Time? Sundials: History of the sundial, Sundial theory, Types of sundial, Sundials in Cambridge, Time: History of Time, Atomic time, Universal Time, Civil time, Local time, Sidereal time, Solar time, What is the time right now? The Calendar: The day, The week, The month, The year, Other calendars, Calendar reform, The Equation of Time, Equinoxes and solstices - updated, Leap Years, Summer Time, and more.
Time clock from Wikipedia, the free encyclopedia.
Time travel from Wikipedia, the free encyclopedia.
TIME TRAVEL - Is it Possible? YES! YouTube video, 2:46 min. A child explains Einstein's theory on the elasticity of time on The Science Channel's "10 Ways to See into the Future."
TIME TRAVEL: What Einstein Did Not See. YouTube video, 4:29 min. Watch time travel in three dimensions. From a book that presents a new approach to time and space. This new approach redefines time into two different components, a vector of Timespace and a scalar of Universal Time.
Time Travel. Everything you always wanted to know about time travel: Time and the Universe, How to build a time machine, A beginner's guide, Does time exist? Wormholes, Einstein Connection, Wormhole Engineering, The ultimate proof.
Time Travel from PBS - NOVA Online. Sagan on Time Travel, Traveling Through Time, Think Like Einstein (Hot Science), Timespeak.
Time Travel and Modern Physics from Stanford Encyclopedia of Philosophy. "Time travel has been a staple of science fiction. With the advent of general relativity it has been entertained by serious physicists."
Today's Calendar and Clock Page. Links to numerous date, time, calendar sites: General sites, Jewish, Moslem, Bahá'í, Chinese ("Lunar") Calendar, Persian and Parsi, Buddhist, Hindu and Other Indian Calendars, Historical Calendars, Countdown scripts, African Calendars, Celestial, World Holidays Calendars, "This Day" Sites, Maya / Aztec Calendars, Name Days, Special Clocks, Reference Material, and Change the Calendar!
Understanding Time. YouTube video, 52:50 min. "... the deep sense we have of time passing from present to past may be nothing more than an illusion ... Brian Greene takes us on the ultimate time-traveling adventure, hurtling 50 years into the future before stepping into a wormhole to travel back to the past ... he will reveal a new way of thinking about time in which moments past, present, and future ... exist all at once. This journey will bring us all the way back to the Big Bang, where physicists think the ultimate secrets of time may be hidden."
What's the Time? from Riverdeep Interactive sLimited. Units of Timekeeping, Pendulum Clocks, Quartz Crystal Clocks, Atomic Clocks.
What is time? - professor Renate Loll, Utrecht University. YouTube, 12:06 min. "Professor Renate Loll (Utrecht University) talks about the question 'What is time' from the perspective of theoretical physics. Often contra-intuitive but always fascinating, Loll reveals the secrets of a quantum theory of times."
www.timeanddate.com. A wide range of topics are covered: Time (World Clock, Search for City, Meeting Planner), Date (Calendar), Counters (countdown to any future date of your choice), Starting dates for Centuries and for Millennia, plus Latest updates.