1 kg Australian Lunar Year of the Ox 2009 silver coin

Australian Lunar silver coins are based on the Chinese Lunar Zodiac 

It is believed that the Chinese lunar calendar was created almost five millennia ago by primeval ruling dynasties. Since that time, the calendar has been continuously improved by astronomers of different royal Chinese courts, culminating in a final version that was calculated according to the earth’s movement around the sun, but fitted into a lunar calendar, thus making it officially a lunisolar calendar. The decision to base the calendar on two celestial bodies stems from the fact that the moon’s motion around the earth is not in synchronisation with the earth’s motion around the sun, creating a time disparity which created a problem for farmers who, of course, needed an accurate calendar that would tell them the best time for planting and harvesting in accordance with the sun’s movement. Originally, the calendar was based on the cycles of the moon, as it was much easier for the ancient astronomers to make the necessary calculation. But, as time passed, they noticed the disparity between the lunar year which consisted of twelve months, each month consisting of 29.5 days which totalled 354 days in a year, and the solar year, which numbered a total of 365.24 days, thus making the lunar year 11 days shorter than the earth’s yearly orbit around the sun. To better synchronise the lunar calendar with the sun, a leap month was added every two or three years similar to that of the modern solar calendar where nearly every 4 years on February 29 an extra leap day is added to align the earth’s revolution around the sun. 

In contrast to most other calendars, the Chinese lunar calendar does not count years in an infinite sequence, but is instead composed of  a 12 year period that is repeated five times in order to get to a cycle that is equal to 60 years. Each year of the period consists of two components, a heavenly stem and a terrestrial branch. The heavenly stem consists of ten symbols, which were the names of the ten days in the week used by the ancient Chinese, while the terrestrial branch consists of 12 animals from the Chinese zodiac cycle. For the creation of one year, each stem is combined with every second terrestrial branch. Thus, when all possible combinations between the heavenly stems and terrestrial branches have been made, this being equal to 60, the final cycle is created and subsequently it starts over once again. This method of cyclical dating is believed to be among the longest continuous sequences of time measurement in history. China today uses the Gregorian calendar, a solar calendar, for all civil purposes, but the lunar calendar is still the main calendar used by various communities in China and East Asia to determine festival dates such as weddings, the Chinese New Year and other auspicious festivities.

The Perth Mint is a world distinguished mint and precious metals refiner that is located in the City of Perth, in Western Australia. The Perth Mint was founded in 1896 by Britain’s Royal Mint in response to the newly discovered gold deposits in Western Australia. Perth Mint’s task was to refine gold ore from the mines and to strike sovereign gold coins from the refined bullion. Between 1899 and 1931 the Pert Mint produced  a considerable amount of gold sovereigns which were distributed in Australia  and throughout the British Empire to be used as circulating currency. British control over Perth Mint was relinquished in 1971 to the Government of Western Australia which then assumed ownership of  the  mint.  Today,  the  Perth  Mint  is  hailed  for  the exceptional  quality  of  its  world  class investment bullion coins like the Kookaburra and Koala silver coins, and the Lunar Series. The Perth Mint has been a member of the London Gold Market (predecessor of the LBMA) since 1934. The swan design, which is the Mint’s official assay stamp registered with the LBMA, is recognised internationally and was inspired by the Mint’s location in Perth, where the main river, the Swan, runs through the city.