EARTH’S MAGNETIC FIELD (Syllabus: GS Paper 1 – Geography)

Context: Geologists at MIT and Oxford University have found ancient rocks in Greenland that bear the oldest remnants of Earth’s early magnetic field.

Key Findings of Study

• The new study extends the Earth's magnetic field lifetime by 200 million years.
• Early Earth may have fostered life due to a strong magnetic field retaining a habitable atmosphere and shielding from solar radiation.
• Despite evidence dating back 3.5 billion years, the exact strength and timing of the early magnetic field were unknown.

Earth’s Magnetic Field

• About: Earth's Magnetic Field & Pole: The Earth’s magnetic field is represented by a field of a magnetic dipole currently tilted at an angle of about 11° with respect to Earth's rotational axis, as if there were an enormous bar magnet placed at that angle through the centre of Earth.

oNote: The North geomagnetic pole actually represents the South pole of Earth's magnetic field, and conversely the South geomagnetic pole corresponds to the north pole of Earth's magnetic field.

oReason: It is because opposite magnetic poles attract and the north end of a magnet, like a compass needle, points toward Earth's South magnetic field, i.e., the North geomagnetic pole near the Geographic North Pole). As of 2015, the North geomagnetic pole was located on Ellesmere Island, Nunavut, Canada.

• Shifting of magnetic poles: Unlike the geographic poles, Earth's magnetic poles are not fixed and tend to wander over time. The magnetic poles flip approximately every 200,000 to 300,000 years according to NASA, though it has been more than twice that long since the last reversal.