GS Paper: Salient Features Of World’S Physical Geography

Why in the News?

Earth’s magnetic north pole, a critical point where the planet’s magnetic field lines converge, is in constant motion due to changes in the Earth’s molten core. Currently located in the Arctic Ocean above Canada, the magnetic north pole has been moving towards Siberia at an accelerated pace.

What is the World Magnetic Model (WMM)?

• The WMM is the standard model used for navigation, attitude, and heading referencing systems that rely on Earth’s geomagnetic field.
• It is widely used in civilian applications, including navigation and heading systems, as well as in military operations.
• The WMM provides accurate data on the Earth’s magnetic field and the location of the magnetic North Pole, combining measurements from ground stations and satellites.
• Revisions and Updates:
  • A new version is updated every five years to address changes in the magnetic field.
  • The latest version, WMM2025, was released on December 17, 2024, and will remain valid until late 2029.
• The WMM is jointly developed by the United States’ National Geospatial-Intelligence Agency (NGA) and the United Kingdom’s Defence Geographic Centre (DGC), with technical support from NCEI and the British Geological Survey (BGS).
• It serves both civilian and military purposes, ensuring accuracy in navigation systems, GPS applications, and other tools dependent on Earth’s magnetic field.

Why is the Magnetic North Pole Moving?

• The magnetic North Pole moves due to the dynamic flow of molten iron and other metals in Earth’s outer core, which generates the planet’s magnetic field.
• These movements cause shifts in magnetic field lines, leading to the pole’s drift over time.
• The pole was first identified in Canada in 1831 and has since moved over 400 km toward Russia.
• Key Observations of Movement:
  • From 1990 to 2000, the pole drifted at a rapid rate of 55 km/year.
  • By 2015, this rate slowed to 35 km/year, but the drift remains unpredictable.
  • Currently, the pole is moving closer to Siberia, reflecting changes in Earth’s core dynamics.
• Impact of Movement:
  • The drift affects navigation systems, aviation routes, and Earth’s magnetic shielding against harmful solar radiation.
  • Scientists monitor this movement using the WMM to ensure updated predictions and mitigate potential impacts on navigation and environmental protection.

Why in the News?

An annular solar eclipse will be visible in parts of South America on October 2, 2023.  It, however, will not be visible from India.

What is a Solar Eclipse?

• A solar eclipse occurs when the Moon moves between the Earth and the Sun, blocking the Sun’s light either fully or partially, casting a shadow on certain parts of the Earth.
• There are four types of solar eclipses:

1. 1. Total Solar Eclipse: When the Moon completely blocks the Sun, turning the sky dark. People in the path of a total solar eclipse can witness the Sun’s corona (its outer atmosphere), which is normally hidden by the bright sunlight.
   2. Annular Solar Eclipse: Occurs when the Moon is at or near its farthest point from Earth. The Moon does not fully cover the Sun, leaving a visible ring of fire around the Moon. This is what people in parts of South America will witness on October 2, 2023.
   3. Partial Solar Eclipse: Happens when the Moon blocks only a part of the Sun, giving it a crescent shape. During both partial and annular eclipses, areas outside the Moon’s umbra (the darkest part of its shadow) experience a partial eclipse. It is the most common type of solar eclipse.
   4. Hybrid Solar Eclipse: The rarest type, where the eclipse shifts between total and annular as the Moon’s shadow moves across the Earth. Some places see a total solar eclipse, while others see an annular one.

Frequency of Solar Eclipses

• A solar eclipse can only occur during the new moon, when the Moon and Sun are aligned on the same side of the Earth.
• A new moon happens approximately every 29.5 days because that is the time it takes for the Moon to orbit the Earth.
• However, solar eclipses don’t happen every month. They occur two to five times annually, but not every new moon results in an eclipse.
• Why don’t they occur every month:
  • The Moon’s orbit around the Earth is tilted by about 5 degrees compared to the Earth’s orbit around the Sun.
  • This means the Moon’s shadow usually misses the Earth.
  • A solar eclipse only occur when the Moon crosses specific points in its orbit, called nodes, where the Moon’s orbit intersects the plane of Earth’s orbit around the Sun.
  • When a new moon occurs at one of these nodes, a solar eclipse is possible.

Why in the News?

In a rare celestial event, Earth’s gravitational field will witness a small asteroid, 2024 PT5, creating a “mini-moon” for two months.

What is Mini-Moon?

• A mini-moon is a small asteroid temporarily captured by Earth’s gravitational field, orbiting the planet for a short period before escaping back into space.
• Unlike Earth’s permanent moon, mini-moons only stay for a few months to a few years before being ejected from orbit.
• Mini-moons are a rare occurrence because most asteroids either pass by Earth or burn up in the atmosphere rather than being captured by Earth’s gravity.
• Mini-moons are usually small, often just a few meters in diameter.
  • For example, 2024 PT5 is only about 33 feet (10 meters) in length.
• They are hard to detect and are usually discovered using advanced telescopic surveys like NASA’s Asteroid Terrestrial-impact Last Alert System (ATLAS).

Significance of Mini-Moons

• Mini-moons offer scientists a unique opportunity to study near-Earth objects, enhancing our understanding of asteroids’ behavior and composition.
• Mini-moons could contain valuable minerals or water, making them potential targets for future space missions to extract resources.
• Studying mini-moons helps scientists learn more about Earth’s gravitational influence and how it interacts with space objects.

Why in the News?

The Volcanic Island of Rapa Nui (also known as Easter Island) has always been mysterious due to its harsh geography and iconic Moai statues.

About Rapa Nui Island

Why in the News?

The Perseid meteor shower, which began in July, is currently at its peak activity from August 11 to 13, 2024.

About Perseid Meteor Shower

Note: In the 1990s, scientists feared comet Swift-Tuttle might hit Earth or the Moon in 2126, but later calculations confirmed safety for two millennia.

Why in the News?

• Astronomers have identified a new Earth-sized exoplanet, named Speculoos-3b, orbiting an ultracool red dwarf star.

About Speculoos-3b

• Speculoos-3b is an Earth-sized exoplanet recently discovered orbiting an ultracool dwarf star.
• It was discovered by a team of astronomers led by Michael Gillon from the University of Liege in Belgium.
• It is located approximately 55 light-years away from Earth.
• Due to its short orbital period, Speculoos-3b receives almost ten times more energy per second than Earth does from the Sun.

Astrophysical Significance of the Discovery

• Prevalence of Ultracool Dwarfs: Ultracool dwarf stars, like the host of Speculoos-3b, constitute about 70% of all stars in our galaxy and are known for their longevity, surviving up to 100 billion years.
• Importance for Life’s Potential: The extended lifespan of these stars provides a stable environment that could potentially support the development of life on orbiting planets.

Why in the news?

Researchers have made a discovery in Mexico, uncovering the world’s deepest blue hole, known as Taam Ja’ Blue Hole (TJBH).

About Taam Ja’ Blue Hole (TJBH)

• TJBH extends at least 1,380 feet (420 meters) below sea level, making it the deepest known underwater sinkhole in the world.
• It is located in Chetumal Bay off the southeast coast of the Yucatan Peninsula.
• It was first discovered in 2021, was originally thought to be 900 feet deep.
• This discovery surpasses the previous record-holder, the Sansha Yongle Blue Hole in the South China Sea, by an impressive 480 feet.

Research Expedition and Findings

• Scientists utilized a conductivity, temperature, and depth (CTD) profiler to collect data about the environmental conditions within the blue hole.
• Despite reaching depths of 1,640 feet (500 meters), the CTD profiler was unable to reach the bottom of TJBH, indicating its remarkable depth.
• Data from the profiler suggested the presence of different water layers within the blue hole, with conditions resembling those of the Caribbean Sea at depths below 1,312 feet (400 meters).

Why in the news?

• The WWF has issued a stark warning regarding the dredging of the Pripyat River, adjacent to the Chernobyl nuclear disaster site.
• Concerns mount as the Pripyat River could transform into a permanent repository of radioactive substances, contaminating the water and food sources.

About Pripyat River

• Pripyat River is a significant waterway in Eastern Europe. It flows through Ukraine, Belarus, and a small portion of Russia.
• It is primarily situated within the Polesian Lowland, a region characterized by marshes, wetlands, and forests.
• The Pripyat River is approximately 761 km (473 miles) long.
• Physical Features:

• Tributaries: It has numerous tributaries, including the Stokhid River, Styr River, and Horyn River. The largest tributary of the Pripyat is the Teterev River, which joins it from the right bank.
• Drainage Basin: Its basin covers an area of around 121,000 square kilometers (46,700 square miles). It is one of the major tributaries of the Dnieper River, which eventually flows into the Black Sea.

Notable event: The Pripyat River gained international attention due to its proximity to the Chernobyl Nuclear Power Plant, where the catastrophic nuclear accident occurred in 1986.