Coronal Mass Ejections (CMEs)

In May 2024, a series of powerful solar eruptions, known as Coronal Mass Ejections (CMEs), resulted in a stunning display of northern lights across Ladakh’s night skies, capturing the attention of astronomers and sky-gazers alike.

About Coronal Mass Ejections (CMEs)

Coronal Mass Ejections (CMEs) are massive bursts of magnetized plasma that are ejected from the Sun’s corona. These ejections can have far-reaching effects on both space weather and Earth’s atmosphere, making them an important subject of study in solar and space science.

Formation of CMEs

• CMEs are triggered by a process called magnetic reconnection.

• Magnetic reconnection occurs when the Sun’s magnetic field lines twist, tangle, and realign themselves. This causes localized magnetic fields that can break through the Sun's surface at active regions, leading to the formation of CMEs.

• These eruptions are often linked with sunspot groups, though solar flares (which are sudden bursts of energy) are not always observed in tandem with CMEs.

Characteristics of CMEs

• Speed: CMEs can travel outward from the Sun at speeds ranging from less than 250 km/s to up to 3000 km/s. The fastest Earth-directed CMEs can reach our planet in as little as 15-18 hours.

• Size: CMEs expand as they move away from the Sun. Larger CMEs can grow to a size that covers nearly a quarter of the distance between Earth and the Sun by the time they reach our planet.

• Solar Activity Cycle: CMEs are most frequent during the solar maximum, which occurs during the Sun’s 11-year cycle of activity, when the Sun is at its most active.

Impact of CMEs on Earth

• When CMEs are directed toward Earth, they can cause geomagnetic storms. These storms occur when the charged particles from the CME interact with Earth’s magnetic field and atmosphere, leading to a variety of impacts, including:

  • Disruptions to satellite operations (navigation, communication, etc.)

  • Interference with communication systems (radio and GPS signals)

  • Disruptions to power grids (potentially causing power outages)

  • Beautiful phenomena like auroras or northern lights in regions near the poles (such as Ladakh, in the case of the May 2024 event).

Geomagnetic Storms and Auroras

• The interaction between the solar wind (charged particles from the Sun) and Earth’s magnetic field leads to the creation of auroras, or northern lights, particularly in the polar regions.

• Ladakh, located in the northern part of India, is not usually a hotspot for auroras, but during powerful solar events like CMEs, the auroras can be visible at unusual latitudes.

• In May 2024, a CME directed toward Earth caused such a geomagnetic storm, resulting in the rare northern lights over Ladakh.