Cosmic radiation is a constant phenomenon, originating from space and bombarding Earth. While India, like the rest of the world, is constantly exposed to this radiation, its intensity fluctuates. This article explores the nature of cosmic rays, their sources, and how they affect us on Earth, particularly focusing on the question of whether there’s an increased risk of cosmic ray exposure in India today.
Cosmic rays are high-energy particles, primarily protons and atomic nuclei, traveling at near light speed. These particles originate from outside our solar system (galactic cosmic rays) and from the Sun (solar cosmic rays). Galactic cosmic rays are remnants of supernova explosions, acting as natural particle accelerators, propelling particles across vast distances. Solar cosmic rays, on the other hand, are emitted by the Sun, either as a continuous solar wind or during sudden solar flares.
The Earth’s magnetic field and atmosphere provide a natural shield against cosmic radiation. The magnetosphere deflects most incoming particles, while the atmosphere absorbs a significant portion of the remaining radiation. This protection significantly reduces the intensity of cosmic rays reaching the Earth’s surface. However, the shielding isn’t uniform. The intensity of cosmic radiation varies with altitude and latitude. Higher altitudes experience greater exposure due to thinner atmospheric shielding. Similarly, polar regions receive more radiation due to the Earth’s magnetic field lines converging at the poles.
While daily fluctuations in cosmic ray intensity occur, predicting a significant increase in exposure on a specific day, like today in India, is challenging without specific data from monitoring stations. Organizations like the Indian Space Research Organisation (ISRO) constantly monitor space weather, including solar activity and cosmic ray flux. Consulting their data would provide the most accurate information on current cosmic ray levels. Generally, unless there’s a significant solar flare event, the day-to-day variation in cosmic ray exposure in India is minimal and poses no immediate health concern.
Even at ground level, a small fraction of cosmic radiation penetrates the atmosphere. On average, individuals are exposed to about 3.5 millisieverts (mSv) of radiation annually, with roughly 10% originating from cosmic rays. This exposure is comparable to other natural radiation sources and significantly lower than the dose received from medical imaging procedures.
While ground-level exposure is relatively low, individuals in certain professions, such as aircrew and astronauts, face higher risks due to increased altitude and time spent in the upper atmosphere or space. Aircrew, especially those on high-altitude or polar routes, can receive annual doses up to 6 mSv. Astronauts, working outside the protection of the Earth’s atmosphere and magnetic field, receive significantly higher doses. For instance, an astronaut on the International Space Station might receive over 0.5 mSv per day.
Cosmic radiation’s interaction with the Earth’s atmosphere produces stunning auroras, predominantly seen at high latitudes. These colorful displays result from collisions between charged particles from the solar wind and atmospheric gases. Oxygen molecules produce the common yellowish-green aurora, while nitrogen creates blue or purplish-red hues.
Interestingly, the study of cellular damage caused by high levels of cosmic radiation contributes to advancements in cancer treatment. Particle accelerators, mimicking the high-energy beams found in space, offer precise tumor targeting while minimizing damage to surrounding healthy tissues. This knowledge transfer between space research and medical technology highlights the unexpected benefits of understanding cosmic radiation.
