The compasses of Greenwich are about to do something I have not done in 360 years

Find a source of magnetism, unknown under the waters of the Pacific What will happen when the magnetic poles of the Earth reverse?The magnetic North Pole is no

The compasses of Greenwich are about to do something I have not done in 360 years
Find a source of magnetism, unknown under the waters of the Pacific What will happen when the magnetic poles of the Earth reverse?The magnetic North Pole is no longer in the same place

Within the next two weeks the compasses of the Royal Observatory of Greenwich in London, the set by the famous meridian, will be something never seen in 360 years. is Your needle will point to true north (or geographic north).

As it explains the astronomical observatory in a press release, the angle at which a needle of the compass between true north and magnetic north is called decline . As the magnetic field changes all the time, so does the declination at any given place. For the last hundreds of years in the Uk, the decline has been negative, which means that the compasses have pointed to the west of true north.

Map of declination zero of Greenwich

The line of declination zero, called agonal, is moving toward the west at a current pace of around 20 km per year. For this month of September, for the first time since 1660, the needle of the compass will point directly to true north in Greenwich before turning slowly to the east.

The Royal Observatory of Greenwich was established in 1676, and from 1836 the site housed an observatory magnetic specialized. The observatory helped to establish the definition of zero-length, paving the way for a system of global reference for maps and navigation that we know today as the meridian of Greenwich, and with him, the Greenwich mean time (GMT). The instruments were moved in 1926 to Abinger, south London, when the electrification of the railways finally made it impossible to measure the magnetic field in Greenwich.

Impact on daily life

"at some point In September, the agony will be with a zero length in Greenwich. This marks the first time since the creation of the observatory that the systems of coordinates geomagnetic and geographic have coincided in this place", explains Ciaran Beggan, a specialist in geomagnetism at the British Geological Survey (BGS).

"The agony will continue passing by the United Kingdom during the next 15 to 20 years. By 2040, all compasses probably will point to the east of true north", he adds. "Currently, it is impossible to predict how it will change the magnetic field for decades or centuries, so that the compass may well point to the east of true north for another 360 years in the United Kingdom".

yes, as pointed out by Beggan, the match is only on Greenwich mean time, because "the line of declination is not straight nor uniform". For that reason, it will not happen the same in the rest of the points of the zero meridian, which in Spain is close to Monte Perdido (Huesca) in the Pyrenees mountains, on the motorway Zaragoza-Fraga -where there is an arc that indicates - and by some towns of Alicante.

The team emphasised that the declination is zero at Greenwich will not have any impact on the daily life. is "The compasses and the GPS will work as it always ; there is no need for anyone to worry about any disorder in daily life," says Beggan.

The pole magnetic north of the Earth has been moving so fast in the last few decades that last February, the scientists released an update with the exact location of the magnetic north, a normal operation, however, was ahead almost a year.

Updated Date: 11 September 2019, 23:01

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