Greenwich RoyalObservatory (Greenwich: Greenwich), formerly known as the Royal Greenwich Observatory, is a comprehensive observatory built by King charles ii of England in Greenwich, London on 1675, and the foundation stone was laid on 10 in August.

At the same time, the king also created the position of Royal Astronomer (the first one is john flamsteed) as the director of the Observatory, "with the most sincere care and efforts, he devoted himself to correcting the celestial catalog and the position of stars, thus correctly determining the longitude and making navigation a perfect art".

history

Sir Jonah Murray suggested the establishment of the Royal Observatory in 1674. Its task is only to measure for the ordnance department. King charles ii was persuaded to hire Flemish to carry out the construction work? .

The Ordnance Department undertook the construction of the Observatory, and Murray provided key instruments and equipment for the Observatory with his own private funds.

Frosted House, originally a part of the Observatory, is the first facility with a specific scientific research purpose in Britain, which was designed by Sir Christopher Lane with the assistance of robert hooke. Its construction cost 520 pounds (20 pounds over budget), which was mainly used to rebuild the Duke Humphrey Tower, because it deviated from due north 13 degrees, which annoyed Genvrain Steed.

Not only did he put the scientific instruments needed by the Flemish people in the catalogue, but over time, he also merged a certain number of other jobs, such as punctuality and later editing the office of Her Majesty's nautical yearbook.

Molly donated two clocks built by Thomas Tampin, which were placed at 20? This is the main room of this one-foot-high octagonal house. They have different designs, each with 13? The foot (3.96 meters) long pendulum is installed in front of the clock, and it swings accurately every 4 seconds. The daily error is unprecedented, only 7 seconds.

Astronomers in Britain have long used the Greenwich Observatory base for measurements: four independent meridians pass through the building.

The meridian basic prime meridian established by 185 1 was ratified at the international conference of 1884, and passed the Airy satellite instrument of the Observatory. For a long time, it was originally indicated by brass bars placed in the courtyard. It was upgraded to stainless steel on 1999 12 16, and it shone with powerful green laser in the night sky of north London.

The ancient prime meridian has been replaced by the modern prime meridian. When Greenwich is an active observatory, the title of geographical coordinates shows that this place is the benchmark of a flat sphere, and its surface is closely consistent with the average sea level, which is called the earth's horizontal plane. There are several benchmarks in the world, each using a different oblate sphere, because the global average sea level fluctuation can be as high as 100 meters.

Modern geodetic reference systems, such as the World Geodetic System and the International Terrestrial Reference System, use a single oblate sphere with the earth as the center. Moving from several spheres to a single world sphere causes all geographical coordinates to move, and some even move by hundreds of meters.

In the modern reference system, the prime meridian moved eastward by102.5m from Greenwich prime meridian marked by stainless steel bars, and now it is 5.3 1 arc second to the west.

Greenwich Mean Time (GMT) is based on Greenwich Mean Time (up to 1954). Since then, GMT time has been calculated by other observatories that are still active.

GMT is now often called Universal Time, which is calculated by observing those wireless power sources from outside the Milky Way, and converted into several forms, including UT0 (Universal Time for Remote Observation), UT 1 (Universal Time for Correcting the Pole Shift) and Coordinated Universal Time (Universal Time for which UT 1 differs from SI seconds by less than 0.9 seconds).

To help other times synchronize with Greenwich Mean Time, Royal astronomer John Pound installed a time ball at 1833. It is set at 1:00( 13:00) in the afternoon of every day of the year (GMT in winter and BST in summer).

The present situation of the observatory

Now, this building is a part of the British National Maritime Museum. It is a museum that collects astronomical and nautical tools, including the famous john harrison Prize-winning maritime clock H4 and his previous three finished products.

Several other man-made clocks that historically provided precision and punctuality for astronomy and navigation are also on display, including the Fedchenko clock made in the Soviet Union in the mid-20th century (the most accurate multi-replica pendulum clock ever made).

It is also the location of the 28-inch refracting telescope made by gruber in 1893, which was the largest telescope of its kind in Britain at that time. The shepherd clock outside the gate of the Observatory is an example of an early electronic clock.

In February 2005, a renovation project costing 654.38+0.5 million pounds was started to provide a new planetarium and other exhibition halls and educational facilities. The Peter Harrison Planetarium with 65,438+020 seats opened in May 2007.