Ini jawaban detail dari European Space Agency (ESA):
1. Yang berubah itu magnetic pole, geographic pole tetap sama, jadi yang berubah hanya arah North South di kompass anda, tapi matahari tetap terbit di tempat yang sama, karena poros dan arah rotasi bumi tetap sama, cuma kompass anda saja yang berubah arah jarumnya.
"Unlike our geographic North Pole, which is in a fixed location, magnetic north wanders. This has been known since it was first measured in 1831, and subsequently mapped drifting slowly from the Canadian Arctic towards Siberia. One of the practical consequences of this is that the World Magnetic Model has to be updated periodically with the pole’s current location. The model is vital for many navigation systems used by ships, Google maps and smartphones, for example. Between 1990 and 2005 magnetic north accelerated from its historic speed of 0–15 km a year, to its present speed of 50–60 km a year. In late October 2017, it crossed the international date line, passing within 390 km of the geographic pole, and is now heading south.
ESA’s Swarm mission is not only being used to keep track of magnetic north, but scientists are using its data to measure and untangle the different magnetic fields that stem from Earth’s core, mantle, crust, oceans, ionosphere and magnetosphere. Our magnetic field exists because of an ocean of superheated, swirling liquid iron that makes up the outer core. Like a spinning conductor in a bicycle dynamo, this moving iron creates electrical currents, which in turn generate our continuously changing magnetic field. Tracking changes in the magnetic field can, therefore, tell researchers how the iron in the core moves."
Peta dan Video Pergeseran Magnetic North Pole dari tahun 1840-2019:
Sumber: https://www.esa.int/.../Tug-of-war_drives_magnetic_north...
2. Kalau axis/poros rotasi bumi itu bergeser hanya sedikit, kira-kira 0,65 arcsec atau 19,5 meter dari tahun 1900 - 2006. Dari tahun 2005-2020 sekitar 0,25 arcsec atau 7,5 meter. (lihat gambar di bawah). Pergerakannya tidak begitu singifikan untuk membuat planet bumi jungkir balik, dan pergerakannya itu tidak lurus tetapi berputar-putar atau 'woobling', mirip gasing yang berotasi sambil meleok-leok karena kehilangan keseimbangan. Pergeseran axis rotasi bumi ini juga di monitor lembaga bernama IERS. Menggunakan banyak satelit (SLR, DORIS) dan radio teleskop (VLBI), jadi perubahan axis rotasi bumi bisa di deteksi berdasarkan perubahan frekuensi sinyal yang di terima dari satelit dan objek2 extraterrestrial seperti quasar.
"Measuring the irregularities of the Earth's rotation
The variability of the earth-rotation vector relative to the body of the planet or in inertial space is caused by the gravitational torque exerted by the Moon, Sun and planets, displacements of matter in different parts of the planet and other excitation mechanisms. The observed oscillations can be interpreted in terms of mantle elasticity, earth flattening, structure and properties of the core-mantle boundary, rheology of the core, underground water, oceanic variability, and atmospheric variability on time scales of weather or climate. The understanding of the coupling between the various layers of our planet is also a key aspect of this research.
The measurements of the earth's rotation are under the form of time series of the so-called Earth Orientation Parameters (EOP). Universal time (UT1),
polar motion and the celestial motion of the pole (precession/nutation) are determined by VLBI. The satellite-geodesy techniques, GPS, SLR and DORIS, determine polar motion and the rapid variations of universal time."
Kalau di plotting, seperti ini dari tahun 2005:
Fakta Menarik: Smartphone yang anda pegang sudah tersambung dengan data yang di sediakan satelit IERS dan ESA karena ketepatan GPS pada aplikasi android/ios di HP anda bergantung pada data yang senantiasa di update oleh lembaga IERS atau ESA setiap hari.
Sumber:
1. https://www.iers.org/IERS/EN/Science/EarthRotation/EarthRotation.html
2. https://data.iers.org/plottool/publicv2/3d.php#interactive
3. https://en.wikipedia.org/wiki/Polar_motion
1. Yang berubah itu magnetic pole, geographic pole tetap sama, jadi yang berubah hanya arah North South di kompass anda, tapi matahari tetap terbit di tempat yang sama, karena poros dan arah rotasi bumi tetap sama, cuma kompass anda saja yang berubah arah jarumnya.
"Unlike our geographic North Pole, which is in a fixed location, magnetic north wanders. This has been known since it was first measured in 1831, and subsequently mapped drifting slowly from the Canadian Arctic towards Siberia. One of the practical consequences of this is that the World Magnetic Model has to be updated periodically with the pole’s current location. The model is vital for many navigation systems used by ships, Google maps and smartphones, for example. Between 1990 and 2005 magnetic north accelerated from its historic speed of 0–15 km a year, to its present speed of 50–60 km a year. In late October 2017, it crossed the international date line, passing within 390 km of the geographic pole, and is now heading south.
ESA’s Swarm mission is not only being used to keep track of magnetic north, but scientists are using its data to measure and untangle the different magnetic fields that stem from Earth’s core, mantle, crust, oceans, ionosphere and magnetosphere. Our magnetic field exists because of an ocean of superheated, swirling liquid iron that makes up the outer core. Like a spinning conductor in a bicycle dynamo, this moving iron creates electrical currents, which in turn generate our continuously changing magnetic field. Tracking changes in the magnetic field can, therefore, tell researchers how the iron in the core moves."
Peta dan Video Pergeseran Magnetic North Pole dari tahun 1840-2019:
Sumber: https://www.esa.int/.../Tug-of-war_drives_magnetic_north...
2. Kalau axis/poros rotasi bumi itu bergeser hanya sedikit, kira-kira 0,65 arcsec atau 19,5 meter dari tahun 1900 - 2006. Dari tahun 2005-2020 sekitar 0,25 arcsec atau 7,5 meter. (lihat gambar di bawah). Pergerakannya tidak begitu singifikan untuk membuat planet bumi jungkir balik, dan pergerakannya itu tidak lurus tetapi berputar-putar atau 'woobling', mirip gasing yang berotasi sambil meleok-leok karena kehilangan keseimbangan. Pergeseran axis rotasi bumi ini juga di monitor lembaga bernama IERS. Menggunakan banyak satelit (SLR, DORIS) dan radio teleskop (VLBI), jadi perubahan axis rotasi bumi bisa di deteksi berdasarkan perubahan frekuensi sinyal yang di terima dari satelit dan objek2 extraterrestrial seperti quasar.
"Measuring the irregularities of the Earth's rotation
The variability of the earth-rotation vector relative to the body of the planet or in inertial space is caused by the gravitational torque exerted by the Moon, Sun and planets, displacements of matter in different parts of the planet and other excitation mechanisms. The observed oscillations can be interpreted in terms of mantle elasticity, earth flattening, structure and properties of the core-mantle boundary, rheology of the core, underground water, oceanic variability, and atmospheric variability on time scales of weather or climate. The understanding of the coupling between the various layers of our planet is also a key aspect of this research.
The measurements of the earth's rotation are under the form of time series of the so-called Earth Orientation Parameters (EOP). Universal time (UT1),
polar motion and the celestial motion of the pole (precession/nutation) are determined by VLBI. The satellite-geodesy techniques, GPS, SLR and DORIS, determine polar motion and the rapid variations of universal time."
Kalau di plotting, seperti ini dari tahun 2005:
Fakta Menarik: Smartphone yang anda pegang sudah tersambung dengan data yang di sediakan satelit IERS dan ESA karena ketepatan GPS pada aplikasi android/ios di HP anda bergantung pada data yang senantiasa di update oleh lembaga IERS atau ESA setiap hari.
Sumber:
1. https://www.iers.org/IERS/EN/Science/EarthRotation/EarthRotation.html
2. https://data.iers.org/plottool/publicv2/3d.php#interactive
3. https://en.wikipedia.org/wiki/Polar_motion
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