5 May 2024

• Astronomy: The Eta Aquariid meteor shower peaked on 5-6 May. Its source body is Halley's Comet.
• Geology: Indonesia's Mount Ruang in Sulawesi continued erupting, triggering the country's highest volcanic alert. The eruption illustrated the geography of the Pacific Ring of Fire.
• Environment: India's 2024 heatwave remained severe, with multiple states under red alert from IMD.
• Defence: Background to the SMART test continued receiving analysis from defence commentators, underscoring India's anti-submarine warfare priorities.

GS area: Science and Technology (Astronomy)

The Eta Aquariid meteor shower was at its peak around 5-6 May 2024. This annual shower is among the more productive of the year.

• Origin: The Eta Aquariids arise from Earth passing through the debris trail left by Halley's Comet. As the Earth intercepts comet debris particles, they burn up in the upper atmosphere, producing visible streaks of light.
• Halley's Comet: A short-period comet with an orbital period of approximately 75-76 years. Its last close approach to Earth was in 1986. The comet leaves two streams of debris: the Eta Aquariids appear in May (from the comet's outbound leg) and the Orionids appear in October (from its inbound leg).
• Peak rate: At peak, the shower produces 30-40 meteors per hour under ideal conditions.
• Best viewing: The Southern Hemisphere gets the best views because the shower's radiant point (in Aquarius) is higher in the sky there. Northern hemisphere observers can still see 10-20 meteors per hour near the radiant's rise before dawn.
• What "radiant" means: The radiant is the point in the sky from which meteors appear to originate. It is not the actual source but an optical effect of perspective. For Eta Aquariids, it lies near the star Eta Aquarii.

Static linkage: Astronomy basics, comets and meteor showers, solar system.

GS area: Geography (Geology), International Relations

Mount Ruang, a stratovolcano in North Sulawesi, Indonesia, continued its eruption in early May 2024. Indonesia's National Disaster Mitigation Agency raised the alert to its highest level.

• Mount Ruang: Located in the Sitaro Islands, North Sulawesi province. It is a stratovolcano, also called a composite volcano, built from alternating layers of lava flows, ash, and fragmented volcanic material.
• Indonesia's volcanic context: Indonesia lies at the convergence of several tectonic plates and has approximately 130 active volcanoes, more than any other country. This places it in the most active portion of the Pacific Ring of Fire.
• Pacific Ring of Fire: An arc of intense seismic and volcanic activity encircling the Pacific Ocean, covering approximately 40,000 km. It runs along the western coasts of North and South America, through Alaska, across Japan and Southeast Asia, and into New Zealand. The activity results from subduction of oceanic plates beneath continental plates at convergent boundaries.
• Alert system: Indonesia's alert system runs from Level 1 (Normal) to Level 4 (Awas/Beware), the highest. The Ruang eruption triggered Level 4, prompting evacuations of nearby islands and temporary closure of Sam Ratulangi International Airport in Manado.
• Stratovolcano characteristics: Explosive eruptions due to high-viscosity, silica-rich magma. Produces pyroclastic flows (fast-moving hot gas and volcanic matter) and lahars (volcanic mudflows mixed with water).

Static linkage: Plate tectonics, volcanic hazards, Indonesia-India relations.

GS area: Environment, Disaster Management

India's 2024 heatwave intensified over the long weekend, with IMD issuing red alerts for states including Rajasthan, Uttar Pradesh, Odisha, Bihar, and Jharkhand.

• IMD colour-coded warnings: Green (no warning), Yellow (watch), Orange (be prepared), Red (take action). A Red Alert means temperatures have reached dangerous levels and immediate protective action is required.
• 2024 El Nino context: The 2024 heatwave was linked to the El Nino event that developed in June 2023. El Nino years typically bring above-normal temperatures to the Indian subcontinent.
• Heat Action Plans: Twenty-three Indian states had Heat Action Plans as of 2024. These plans coordinate hospitals, cool shelters, water distribution, and public communication during extreme heat events.
• National Disaster Management Authority (NDMA): NDMA publishes national guidelines on heatwave preparedness. State Disaster Management Authorities implement them at the local level.
• Health burden: Heat stroke occurs when core body temperature rises above 40 degrees Celsius and the body's thermoregulatory system fails. Elderly individuals, outdoor workers, and children are most vulnerable.

Static linkage: IMD, disaster management, climate change adaptation.

GS area: Science and Technology (Defence), International Relations

Following the SMART test of 1 May, defence analysts examined India's broader anti-submarine warfare (ASW) priorities in the Indian Ocean.

• Submarine threat in the Indian Ocean: China's People's Liberation Army Navy (PLAN) submarines regularly operate in the Indian Ocean. China maintains the world's largest submarine fleet by number.
• India's ASW assets: The Indian Navy uses the P-8I Poseidon maritime patrol aircraft (acquired from the United States), the indigenously developed INS Kiltan (a Kamorta-class ASW corvette), and shipboard SONAR systems. The SMART system adds a long-range standoff capability.
• SONAR: Sound Navigation and Ranging. The primary detection technology for submarines. Passive SONAR listens for sounds; active SONAR emits sound pulses and listens for returns.
• Indian Ocean Region (IOR): Approximately 80 per cent of global seaborne oil trade passes through the Indian Ocean. Controlling submarine approaches to the IOR's chokepoints (Strait of Hormuz, Strait of Malacca, Bab-el-Mandeb) is a strategic priority.
• Project 75I: India's next submarine acquisition programme, aimed at procuring six advanced conventional submarines with Air Independent Propulsion (AIP) systems.

Static linkage: Indian Ocean geopolitics, naval capability, Indo-Pacific strategy.

GS area: Environment, Geography

The 2024 pre-monsoon cyclone season was being monitored closely as the heatwave over land coincided with rising sea surface temperatures in the Bay of Bengal.

• Cyclone formation requirements: Warm sea surface temperatures (above 26-27 degrees Celsius to a depth of 60 metres), adequate moisture, and atmospheric instability. The Coriolis effect provides the rotational force.
• Bay of Bengal vs. Arabian Sea: The Bay of Bengal is more cyclone-prone than the Arabian Sea. Approximately 70 per cent of tropical cyclones in the North Indian Ocean form in the Bay of Bengal.
• IMD's role: IMD is the designated Regional Specialised Meteorological Centre (RSMC) for the North Indian Ocean. It names and tracks all tropical cyclones in the region. The naming list is determined by a panel of 13 member nations of the World Meteorological Organisation (WMO).
• Cyclone season: The peak cyclone season in the Bay of Bengal is October-December (post-monsoon). A secondary pre-monsoon season occurs in April-June.

Static linkage: Indian Ocean meteorology, IMD, disaster management.

• PM SVANidhi expansion: The government reviewed PM SVANidhi implementation data. The scheme has disbursed working capital loans to over 60 lakh street vendors across India since its launch in 2020. It is administered by the Ministry of Housing and Urban Affairs.
• Space weather: The early May solar storm (later confirmed as a G5 event on 10-11 May) was being tracked by NOAA and IMD. Solar maximum of Solar Cycle 25 was approaching, raising the frequency of coronal mass ejections.
• World Press Freedom Day: 3 May is World Press Freedom Day, observed annually since 1994. It was established by the UN General Assembly in 1993. India ranked 159th out of 180 countries in the 2024 World Press Freedom Index published by Reporters Without Borders (RSF).