Mains – 3rd Nov 23
Coronal Mass Ejections
Why in news?
Recently, experts warned about coronal mass ejections.
About
Coronal Mass Ejections (CMEs) are large expulsions of plasma and magnetic field from the Sun’s corona (Sun’s atmosphere).
Compared to solar flares — bursts of electromagnetic radiation that travel at the speed of light, reaching Earth in just over 8 minutes — CMEs travel at a more leisurely pace, relatively speaking. At their highest speeds of almost 1,900 miles per second (3,000 kilometers per second), CMEs can reach Earth in about 15 to 18 hours. These relatively slower travel times are useful as they give us more time to prepare for such an arrival.
Coronal mass ejections form similarly to solar flares — a result of the twisting and realignment of the sun’s magnetic field, known as magnetic reconnection. CMEs usually take place around sunspot groups and are often accompanied by a solar flare, though the two don’t always occur in tandem.
Impact of CME
CMEs can wreak havoc with power grids, telecommunication networks and orbiting satellites and expose astronauts to dangerous doses of radiation.
Sun
- Our Sun is a medium-sized star with a radius of about 435,000 miles (700,000 kilometers). Many stars are much larger – but the Sun is far more massive than our home planet: it would take more than 330,000 Earths to match the mass of the Sun, and it would take 1.3 million Earths to fill the Sun’s volume.
- The Sun is about 93 million miles (150 million kilometers) from Earth.
- The Sun is a huge ball of hydrogen and helium held together by its own gravity.
The inner layers are the Core, Radiative Zone and Convection Zone. The outer layers are the Photosphere, the Chromosphere, the Transition Region and the Corona.
Core
- The core is plasma, but its movement is extremely similar to that of a gas. The temperature of the core of the Sun is around 27 million degrees Fahrenheit.
- In the core, nuclear reactions occur that create helium from hydrogen atoms. This releases huge amounts of energy, and it starts to move outwards toward the other layers. This energy eventually becomes the light and heat we receive on Earth.
Radiative Zone
- The radiative zone is the second inner layer of the Sun. It sits outside of the core, and it holds its extremely high temperature. The zone itself has a temperature of around 7 million degrees Fahrenheit.
- This layer serves as a passage for all the energy that is released by the core. Photons travel through the radiative zone, and they can’t travel through long ranges of space, so it takes almost 50 million years for a photon to travel through this layer of the Sun.
Convection Zone
- In this layer, all of the hot material found near the center of the Sun rises cools down and drops back into the radiative zone to get more heat.
- This is the movement that creates sunspots and solar flares. This layer marks the border of what we usually refer to as the Sun.
Photosphere
- The photosphere is the deepest layer of the Sun that we can observe directly. It reaches from the surface visible at the center of the solar disk to about 400 km above that.
- The temperature in the photosphere varies between about 6500 K at the bottom and 4000 K at the top
Chromosphere
- The chromosphere is a layer in the Sun between about 400 km and 2100 km above the solar surface (the photosphere).
- The temperature in the chromosphere varies between about 4000 K at the bottom (the so-called temperature minimum) and 8000 K at the top.
Transition Region
- The transition region is a very narrow (100 km) layer between the chromosphere and the corona where the temperature rises abruptly from about 8000 to about 500,000 K.
Corona
- The corona is the outermost layer of the Sun, starting at about 2100 km above the solar surface (the photosphere).
- The corona cannot be seen with the naked eye except during a total solar eclipse, or with the use of a coronagraph.
- The temperature in the corona is 500,000 K (900,000 degrees F, 500,000 degrees C) or more, up to a few million K.
Effect of CME
If a CME arrives at Earth, it can produce a geomagnetic storm, which, in turn, can cause anomalies and disruptions to the modern conveniences we have come to rely on. For example, fluctuating magnetic fields associated with these storms induce currents in long wires like power lines, potentially leading to wide-spread blackouts in extreme cases.
Ceiling on stocks of Agri Produce
Why in news?
Ministry of Consumer Affairs, Food & Public Distribution has imposed limits on Stock of Wheat that can be held by traders, wholesalers, retailers, big chain retailers and processors. The Ministry has also imposed stock limits on Tur and Urad by invoking the Essential Commodities Act (ECA), 1955.
Essential Commodities Act 1955
- There are two main aims of this Act:
- To maintain or increase the supply of these essential commodities, and
- To secure equitable distribution and availability of these essential commodities.
- Section 2(A) of the Act states that an “essential commodity” means a commodity specified in the Schedule of the Act.
- The Centre, if it is satisfied that it is necessary to do so in the public interest, can notify an item as essential, in consultation with state governments.
- By declaring a commodity as essential, the government can control the production, supply, and distribution of that commodity, and impose a stock limit.
- The Drug Price Control Oder and such other orders have been issued under the powers of the ECA.
There are 7 commodities that are specified in the schedule:
- Drugs (this is used in the same sense as defined under clause b of Section 3 of the Drugs and Cosmetics Act, 1940);
- Fertilizers, whether organic, inorganic or mixed;
- Foodstuffs, including edible oils and its seeds;
- Hank yarn, made wholly with cotton;
- Petroleum and its products;
- Jute, whether in the form of raw or textiles;
- Seed, whether of fruits and vegetables, of cattle fodder, or of jute.