Coronal Mass Ejections

Why is in news? Astronomers spot a surprising solar eruption that maintains constant temperature

• Scientists tracking the continuous evolution of the energy state of the core of a solar eruption that occurred on July 20, 2017, have found it strangely maintained a constant temperature as it erupted energetic and highly magnetised plasma from the solar corona into space.
• The finding can improve our understanding of how such eruptions can impact communication systems on Earth.
• Coronal Mass Ejections (CMEs) are large-scale eruptions of charged particles (plasma) and magnetic fields from the solar atmosphere into space.
• The Sun is an extremely active object, spewing out vast quantities of gas and plasma in many violent events. A class of such eruptions are Coronal Mass Ejections (CMEs).
• CMEs are the most powerful explosions happening in the solar system.
• They can disrupt a range of ground- and space-based technologies and satellites on Earth. Thus, it is crucial to understand their evolution and propagation through interplanetary space.
• There is a wide range of plasma temperatures within CMEs, from cold chromospheric material (around 104 K) to hot plasma (around 107 K).
• When CMEs propagate, several processes can exchange energy (electrical, kinetic, potential, thermal, and so on.), thereby heating or cooling the plasma.
• The underlying cause of CMEs is not well understood. Astronomers agree, however, that the sun’s magnetic field plays a major role.
• Though CMEs can occur anywhere on the Sun, it is primarily those which originate from regions near the centre of the visible solar surface (called the photosphere) that are important for study, since they may propagate directly towards the Earth.
• This field of research helps to understand Space Weather.
• When the plasma cloud hits our planet, a geomagnetic storm follows.
• A geomagnetic storm is a major disturbance of Earth's magnetosphere (space controlled by earth’s magnetic field) that occurs when there is a very efficient exchange of energy from the solar wind into the space environment surrounding Earth.
• They can trigger intense light in the sky on Earth, called auroras.
• Some of the energy and small particles travel down the magnetic field lines at the north and south poles into Earth’s atmosphere.
• There, the particles interact with gases in the atmosphere resulting in beautiful displays of light in the sky.
• The aurora in Earth’s northern atmosphere is called an aurora borealis or northern lights. It’s southern counterpart is called an aurora australis or the southern lights.