If a major solar storm (solar flare) reaches the Earth, which of the following are the possible effects on the Earth ?

1. GPS and navigation systems could fail.

2. Tsunamis could occur at equatorial regions.

3. Power grids could be damaged.

4. Intense auroras ‘could occur over much of the Earth.

5. Forest fires could take place over much of the planet.

6. Orbits of the satellites could be disturbed.

7. Shortwave radio communication of the aircraft flying over polar regions could be interrupted.

Select the correct answer using the code given below:

The correct option is 1, 3, 4, 6 and 7 only.

A solar flare is a massive explosion on the Sun that releases energy, light, and high-speed particles into space. When these particles reach the Earth, they interact with the Earth's magnetic field and atmosphere, causing various geomagnetic disturbances. Let us analyze each of the given effects step-by-step to understand why this option is correct:

1. GPS and navigation systems could fail: (Correct)
Solar storms disturb the ionosphere, the layer of the Earth's atmosphere used for propagating radio signals. This disturbance introduces errors in the travel time of GPS signals, leading to inaccurate positioning or complete signal failure.

2. Tsunamis could occur at equatorial regions: (Incorrect)
Tsunamis are giant waves caused by earthquakes, volcanic eruptions, or landslides occurring under the ocean floor. They are tectonic and geological events, completely unaffected by solar activity or geomagnetic storms.

3. Power grids could be damaged: (Correct)
The fluctuating magnetic fields during a solar storm induce electric currents in long conductors on the Earth's surface, such as power lines. These Geomagnetically Induced Currents (GICs) can overload transformers and cause widespread damage to electrical power grids.

4. Intense auroras could occur over much of the Earth: (Correct)
Auroras (Northern and Southern Lights) occur when charged particles from the Sun collide with gases in the Earth's atmosphere. During major solar storms, the auroral oval expands, making these intense light displays visible at much lower latitudes than usual.

5. Forest fires could take place over much of the planet: (Incorrect)
Solar storms do not increase the surface temperature of the Earth directly or cause lightning/ignition events on the ground that would spark forest fires over much of the planet.

6. Orbits of the satellites could be disturbed: (Correct)
The intense radiation heats the Earth's upper atmosphere, causing it to expand outwards. This increases the atmospheric density at the altitudes where low-Earth orbit satellites travel, creating additional drag that slows them down and alters their orbits.

7. Shortwave radio communication of the aircraft flying over polar regions could be interrupted: (Correct)
Polar regions are particularly vulnerable because the Earth's magnetic field lines direct solar particles down into the polar atmosphere. This increases ionization in the lower ionosphere, which absorbs high-frequency (shortwave) radio waves instead of reflecting them, leading to a radio blackout for polar flights.

Thus, statements 1, 3, 4, 6, and 7 are indeed the possible effects of a major solar storm on Earth, making the selected code correct.