The Universe in a year!
The American astronomer Carl Sagan (1934—96) first suggested a “cosmic calendar” as a way of helping people understand the history of the Universe. He put everything into the scale of a calendar year: the galaxies are formed over nine months and the Earth appears in September. All human history is crowded into the last five minutes of the last day of the year. Recent time has to be divided into seconds and fractions of a second. So everything that happened over the last 475 years takes place in less than the last second of the Last minute of the year.
1 jan (midnight) Big Bang — Universe forms
15 Mar First stars and galaxies form
1 May Milky Way galaxy forms
8 Sep Sun forms
9 Sep Solar system forms
12 Sep Earth forms
13 Sep Moon forms
20 Sep Earth’s atmosphere forms
1 Oct Earliest known life on Earth
7 Oct Earliest known fossils
18 Dec First many-celled life forms
19 Dec First fish
21 Dec First land plants; first insects
23 Dec First reptiles
24 Dec First dinosaurs
26 Dec First mammals
27 Dec First birds
28 Dec First flowering plants
28 Dec Dinosaurs extinct
31 Dec(11:55 pm) Homo sapiens (modern human) appears
Hour:minute:second/fractions of second
11:59.50.487 pm Great Pyramid is built (2520 BC)
11:59.55.333 pm Great Wall of China is built (215 BC)
11:59.56.785 pm Roman Empire falls (AD 476)
11:59.58.026 pm Battle of Hastings (1066)
11:59.58.921 pm Columbus lands in America (1492)
11:59.59.128 pm Shakespeare writes his first plays (1588—90)
11:59.59.874 pm World War II ends (1945)
11:59.59.891 pm Mount Everest is climbed (1953)
11:59.59.924 pm Man lands on the Moon (1969)
The world in a single day
In one day (24 hours or 1440 minutes or 86,400 seconds) the world turns once on its axis. During that time, on average:
- 358,522 peopLe are born
• 155,012 people die
• 203,510 are added to the world’s population.
The following are some Landmarks in the history of telling the time.
Sundials are used in Egypt: as the Earth rotates, the gnomon
— the upright part of the sundial — casts a shadow which moves to indicate the time.
c 400 BC
Water clocks are used in Greece: as water drains from a container, each level it reaches represents a period of time.
In England people use candles marked with time intervals.
The hourglass, familiar to us as an eggtimer, is used by monks to show times of prayer.
The first clock with a dial is installed in Norwich Cathedral, England.
The first clock to strike the hours is made in Milan, Italy.
The oldest known surviving
alarm clock is made in
CLocks are first used in people’s homes.
Salisbury Cathedral’s clock is installed. This is the world’s oldest clock in working order.
The earliest description of a
watch is written in Italy.
The idea of the pendulum clock is proposed by Vincenzio GaliLei, son of the famous astronomer Galileo.
The first pendulum clocks are made in Holland.
The firstwatches with minute and second hands are made.
John Harrison’s marine chronometer is made. Accurate timekeeping at sea is important for calculating position, but previously the rolling of a ship had made it impossible.
Greenwich Mean Time becomes the standard from which time around the world is set.
The first practical wristwatches are made for the German navy.
The first quartz crystal clock is made.
The first atomic clock is built.
The first battery watches are marketed in the USA.
Quartz wristwatches are first sold in Japan.
Digital watches and displays become widely used and can be made and sold cheaply.
40 radio clocks around the world transmit signals that enable people to set their clocks and watches accurately.
The Earth is constantly turning on its axis. If people
everywhere set their clocks to the same time, midnight would be in the middle of the night on one side of the globe, but the middle of the day on the opposite side. To avoid this problem the Earth is divided into artificial time zones. These generally follow lines of longitude — imaginary Lines running from the North to the South Pole. Some Large countries, such as the USA, cover several time zones. Mainland USA is divided into Atlantic, Eastern, Central, Mountain, Pacific and Alaska zones,
, with Hawaii and other islands falling into further zones. Since the Greenwich Prime Meridian (0°) was
established in 1884, there have been 24 time zones,
a each of 15° longitude and an hour apart. Those to
the east are ahead of Greenwich by one hour per
zone, Those to the west are behind by one hour each. Some countries, such as India, have chosen zones halfway between those on either side, so that the whole country can use the same time.
The International Date Line
The Earth makes one complete turn in every 24 hours, In that time, each of the 360 degrees of longitude passes the Sun. This means that time progresses eastwards by four minutes for every degree of Longitude. The International Date Line is an imaginary line running between the North and South Poles which marks the end of one day and the beginning of another. Countries to the east of the Date Line are always a day ahead of those to the west. Travellers who cross the line either gain or lose a day, depending on which direction they are going.Most of the Date Line follows the 180° Meridian (on the opposite side of the globe from 0°, the Greenwich Meridian). The line generally passes through sea, but where it would pass through or near certain land areas, it is adjusted. It zigzags around islands, putting them either into the west or the east, and avoids dividing Siberia into two time zones.
Names of months
The names of the months in EngLish (as weLl as in many other Languages) come from Latin words.
Januarius — this month was dedicated to Janus, the Roman god of doors. Janus had two faces, one looking back at the oLd year and the other looking forward to the new year.
Februarius — Februa was the Roman purification festivaL, which took place at this time of year.
Martius — from Mars, the Roman god of war.
Aprilis — from aperire, Latin for open, because pLants begin to open during this month.
Maius — probabLy comes from Maia, the Roman goddess of growth and increase.
Junius — either from a Roman famiLy name junius, which means young, or perhaps after the goddess Juno.
Julius — after Julius Caesar. This month was named in Caesar’s honour by Mark Antony in 44 BC. PreviousLy this month was caLled Quintilis from the word quintus, five, as it was the fifth month in the Roman calendar.
Augustus — named in 8 BC in honour of Emperor Augustus.
September — from
septem, seven, because it was the seventh month in the Roman calendar.
October — from octo, eight (as in octopus, which has eight legs), the eighth month in the Roman calendar.
November — from novem, nine, the ninth month in the Roman caLendar.
December — from decem, ten, the tenth month in the Roman calendar.
Just a second
A second does not sound very long, but by the time you have read this sentence, almost five of them will have gone by. Watch an average-Length film and more than 5,000 seconds wilL tick away. In a Lifetime of 80 years, there are more than 2.5 billion seconds — but you will spend more than 800 miLlion of them asleep!
1 minute 60
1 hour 3,600
1 day 86,400
1 week 604,800
1 year 31,536,000
Naming the days of the week
The ancient BabyLonians, then the Romans, named the days of the week after planets and other bodies they saw in the sky.
Tiu’s-day: Mars, the Roman god of war, was adopted in Scandinavian mythology as the warrior Tiu orTiw.
Woden’s day: the Roman god Mercury became the Scandinavian god Woden.
Thor’s day: Like the Roman god Jupiter, Thor was a thunder god.
Freyja’s day: like Venus, Freyja or Frigg was the goddess of Love.
One-billionth of a trillionth of a second (the time a photon would take to cross the width of one electron at the speed of light)
0.000000000000001 of a second
(one-trillionth) of a second
0.000000001 (one-billionth) of a second
of a second
of a second; the blink of an eye takes 50—80 milLiseconds
0.01 (one-hundredth) of a second
760 of a minute
Sunrise to sunrise, or sunset to sunset, or midnight to midnight; 24 hours
Seven days; in Shakespearean times, it was also caLled a sennight, or seven nights
Two weeks (from the Old English for 14 nights)
A period of three months
36574 days, 52 weeks, or
The time it takes for a place on the Earth directly facing the Sun to make one revoLution and return to the same position (approximateLy 23 hours 56 minutes)
The time taken for the Erth to make a complete revolution around the Sun, equal to 365.242 19 solar days or 365 days 5 hours 48 minutes 45.51 seconds; also calLed a tropical year or astronomical year
10 years; also called a decennium
1,000 years; also caLled
A period of time measured from some important event
aeon or eon
A Long period of time, usuaLly thousands of years; in geology and astronomy it is àne billion years
Watches at sea
Here are some of the words used to describe units of time. At sea, the 24-hour day is traditionally divided into seven watches, during whichpart of a ship’s crew are on duty.
First Watch 8 pm to midnight 2000 to 0000
Middle Watch midnight to 4 am 0000 to 0400
Morning Watch 4 am to 8 am 0400 to 0800
Forenoon Watch 8 am to noon 0800 to 1200
Afternoon Watch noon to 4 pm 1200 to 1600
First Dog Watch 4 pm to 6 pm 1600 to 1800
Last Dog Watch 6 pm to 8 pm 1800 to 2000
How long does it take?
Event Time taken (seconds)
One beat of a fly’s wing (1/1,000 second) 0.001
Flash of lightning (1/1,000 second) 0.001
One beat of hummingbird’s wing (80 times a second) 0.0125
Mouse heartbeat (10.8 times a second) 0.09
Blink of a human eye 0.33
Human heartbeat 1.0
Light reaching Earth from the Moon 1.2
Land Speed record: car thrust SSC travelling 1km 2.9
Record-breaking Jamaican athlete Asafa Powell to run 100m 9.77
Bullet Train to travel 1km 13.75
Space Shuttle to travel 100km 15
Light reaching Earth from the Sun 497
The rotation of the Earth is slowing down. This means that a solar day (the time it takes Earth to make one complete revolution) and the time shown by atomic clocks would gradually diverge. This problem has been solved by adding “leap seconds”. There have been 22 leap seconds since 1972. The last one was added on 31 December 2005, which delayed New Year’s Day 2006 by one second!
Most of the world’s countries and cultures use the Gregorian calendar, but some base their calendars on more ancient systems. Other countries have adopted an alternative calendar at some point in their history.
3761 BC Jewish calendar starts
2637 BC Original Chinese calendar starts
45 BC Julian calendar adopted by Roman Empire
0 Christian calendar starts Hindu calendar starts
79 Hindu Calendar Starts
597 Julian calendar adopted in Britain
622 Islamic calendar starts
1582 Gregorian calendar introduced in Catholic countries
1752 Ju[ian calendar abandoned, Gregorian calendar adopted in Britain and its colonies, including America
1873 Japan adopts the Gregorian calendar
1949 China adopts the Gregorian calendar
The Mayan people lived in the Yucatan area of present-day Mexico and the neighbouring region. They built amazing pyramids and temples, and had an astonishing knowledge of astronomy. Their culture had declined by the time Spanish invaders occupied their territory in the 16th century, but we know something about it from the remains found. The Haab or civil calendar of the Maya had 18 months made up of 20 days each. Five extra days — considered particularly unlucky — were added at the year’s end, known as Uayeb, giving a year of 365 days.
Months Months Months
1.Pop 7.Yaxxkin 13.Mac
2.Uo 8.Mol 14.Kankin
3.Zip 9.Chen 15.Muan
4.Zotz 10.Yax 16.Pax
5.Tzec 11.Zac 17.Kayab
6.Xul 12.Ceh 18.Cumku
The Gregorian calendar is the one most used nowadays. It is named after Pope Gregory XIII who introduced it in 1 582. There is a leap year every four years (or more precisely, 97 leap years every 400 years).This means that the year corresponds closely with the astronomical year (365.242 19 days) so that it is just one day oUt in every 3,300 years.
* In a Leap year, February has 29 days
Some non-Catholic countries such as Britain refused to adopt the Gregorian calendar at first. The Julian calendar previously used in Britain was based on a solar year, the time taken for the Earth to rotate around the Sun. This is 365.25 days, which is fractionally too long (it is actually 365.242 19 days), so the calendar steadily fell out of line with the seasons. In 1752 Britain decided to correct this by abandoning the Julian calendar in favour of the Gregorian. By doing so, 3 September instantly became 14 September — and, as a result, nothing whatsoever happened in British history between 3 and 13 September 1752. Many people believed their lives would be shortened. They protested in the streets, demanding, ‘Give us back our 11 days!”
Present-day China uses the Gregorian calendar for most purposes, but traditional festivals such as Chinese New Year take place according to the ancient Chinese calendar. Legend has it that this was started during the reign of Emperor Huangdi in 2637 BC, and relates to the positions of the Moon and Sun. It follows a 60-year cycle which combines a heavenly stem and earthly branch, represented by a zodiac animal.
The first year of the cycle is jia-zi,
the second yi-chou, and so on; the
11th year is jia-xu, 12th yi-hai and
13th bing-zi. This continues until
the 60th year (gui-hai) and then
starts again. Each earthly
branch is believed to be
linked with certain
born in the year
of the dragon, for
instance, are thought
to be especially lucky.
The Islamic year is about 11 days shorter than a year in the Gregorian calendar. Although the Islamic calendar started 622 years later, it is gaining on the Gregorian. The two will eventually coincide — but not until the year 20874.
Hebrew and Islamic calendars
The Hebrew (Jewish) and Islamic (Muslim) calendars are based on the lunar (Moon) cycle. Every month starts
approximately on the day of a new Moon, or when a crescent is first seen after a new Moon. But because the visibility of
the Moon varies according to the weather, the start date cannot be determined in advance, so printed calendars may vary by a few days. Tishri/Muharram corresponds approximately with September/October in the Gregorian calendar, Heshvan/Safar with October/November, and so on.
Hebrew Months Days IslamicMonths
1.Tishri 30 Muharram(Holy Month)
2.Heshvan 29 Safar
3.Kishlev 30 Rabi’ a 1
4 Tevet 29 Rabi’a 2
5 Shevat 30 Jumada 1
6 Adar 29 Jumada 2
7 Nisan 30 Rajab(Holy Month)
8 lyar 29 Sha’ban
9 Sivan 30 Ramadan(Month of Fasting)
10.Tammuz 29 Shawwal
11.Av 30 Dhu al-Q’ adah(Holy Month)
12.Elul 29 Dhu al-Hijjah
The Indian calendar is based on the motions of the Sun and Moon and is dated from the so-called Saka Era, equivalent to AD 79. It is used for dating religious and other festivals, but the Gregorian calendar is used for official dates.
1 Caitra (30days)
2 Vaisakha (31 days)
3 jyaistha (31 days)
4 Asadha (31 days)
5 Sravana (31 days)
6 Bhadra (31 days)
7 Asvina (30days)
8 Kartika (30days)
9 Agrahayana (30days)
10 Pausa (30days)
11 Magha (30days)
12 PhaLguna (30days)
* In a leap year, Caitra has 31 days, and 1 Caitra coincides with 21 March