SPACE WEATHER (ഭൂമിയിലേക്ക് വമ്പന്‍ സൗരജ്വാലയെത്തുന്നു )

ഭൂമിയിലേക്ക് വമ്പന്‍

സൗരജ്വാലയെത്തുന്നു

Space Weather

 Sun with large prominence Solar flares produce high energy particles and radiation that are dangerous to living organisms. However, at the surface of the Earth we are well protected from the effects of solar flares and other solar activity by the Earth's magnetic field and atmosphere. The most dangerous emissions from flares are energetic charged particles (primarily high-energy protons) and electromagnetic radiation (primarily x-rays).The x-rays from flares are stopped by our atmosphere well above the Earth's surface. They do disturb the Earth's ionosphere, however, which in turn disturbs some radio communications. Along with energetic ultraviolet radiation, they heat the Earth’s outer atmosphere, causing it to expand. This increases the drag on Earth-orbiting satellites, reducing their lifetime in orbit. Also, both intense radio emission from flares and these changes in the atmosphere can degrade the precision of Global Positioning System (GPS) measurements.

The energetic particles produced at the Sun in flares seldom reach the Earth. When they do, the Earth's magnetic field prevents almost all of them from reaching the Earth's surface. The small number of very high energy particles that does reach the surface does not significantly increase the level of radiation that we experience every day.The most serious effects on human activity occur during major geomagnetic storms. It is now understood that the major geomagnetic storms are induced by coronal mass ejections (CMEs). Coronal mass ejections are usually associated with flares, but sometimes no flare is observed when they occur. Like flares, CMEs are more frequent during the active phase of the Sun's approximately 11 year cycle. The last maximum in solar activity was in the year 2000. The next maximum is expected to occur in 2013.

Coronal mass ejections are more likely to have a significant effect on our activities than flares because they carry more material into a larger volume of interplanetary space, increasing the likelihood that they will interact with the Earth. While a flare alone produces high-energy particles near the Sun, some of which escape into interplanetary space, a CME drives a shock wave which can continuously produce energetic particles as it propagates through interplanetary space. When a CME reaches the Earth, its impact disturbs the Earth's magnetosphere, setting off a geomagnetic storm. A CME typically takes 3 to 5 days to reach the Earth after it leaves the Sun. Observing the ejection of CMEs from the Sun provides an early warning of geomagnetic storms. Only recently, with SOHO, has it been possible to continuously observe the emission of CMEs from the Sun and determine if they are aimed at the Earth.astronaut on space walkOne serious problem that can occur during a geomagnetic storm is damage to Earth-orbiting satellites, especially those in high, geosynchronous orbits. Communications satellites are generally in these high orbits. Either the satellite becomes highly charged during the storm and a component is damaged by the high current that discharges into the satellite, or a component is damaged by high-energy particles that penetrate the satellite. We are not able to predict when and where a satellite in a high orbit may be damaged during a geomagnetic storm.Astronauts on the Space Station are not in immediate danger because of the relatively low orbit of this manned mission. They do have to be concerned about cumulative exposure during space walks. The energetic particles from a flare or CME would be dangerous to an astronaut on a mission to the Moon or Mars, however.

Another major problem that has occurred during geomagnetic storms has been the temporary loss of electrical power over a large region. The best known case of this occurred in 1989 in Quebec. High currents in the magnetosphere induce high currents in power lines, blowing out electric transformers and power stations. This is most likely to happen at high latitudes, where the induced currents are greatest, and in regions having long power lines and where the ground is poorly conducting.auroraThese are the most serious problems that have occurred as a result of short-term solar activity and the resulting geomagnetic storms. A positive aspect of geomagnetic storms, from an aesthetic point of view, is that the Earth's auroras are enhanced.The damage to satellites and power grids can be very expensive and disruptive. Fortunately, this kind of damage is not frequent. Geomagnetic storms are more disruptive now than in the past because of our greater dependence on technical systems that can be affected by electric currents and energetic particles high in the Earth's magnetosphere.

Could a solar flare or CME be large enough to cause a nation-wide or planet-wide cataclysm? It is, of course, impossible to give a definitive answer to this question, but no such event is known to have occurred in the past and there is no evidence that the Sun could initiate such an event.

ഭൂമിയിലെ വാര്‍ത്താവിനിമയസംവിധാനങ്ങളെയാകെ ബാധിക്കുന്ന തരത്തില്‍ വമ്പന്‍ സൗരജ്വാലസൂര്യനിലുണ്ടായതായി അമേരിക്കന്‍ ബഹിരാകാശ ഏജന്‍സിയായ നാസ. സൂര്യനില്‍ ഉടലെടുക്കുന്ന വന്‍ വൈദ്യുതകാന്തിക കാറ്റാണ് സൗരജ്വാല എന്നറിയപ്പെടുന്നത്.സൗരജ്വാലയുടെ സ്വാധീനം ഭൂമിയിലെ അയണോസ്ഫിയറിനെ ബാധിക്കുന്നതിനാല്‍ വൈദ്യുതകാന്തികതരംഗങ്ങള്‍ ഉപയോഗിക്കുന്ന എല്ലാ ഉപകരണങ്ങളും താത്കാലികമായി തകരാറിലായേക്കും. മൊബൈല്‍ഫോണ്‍, റേഡിയോ, ടെലിവിഷന്‍, ജി.പി.എസ്, ഡി.ടി.എച്ച്, വയര്‍ലസ് സംവിധാനങ്ങളെയും കൃത്രിമ ഉപഗ്രഹങ്ങളില്‍നിന്നുള്ള തരംഗങ്ങളെയുമൊക്കെ ഈ സൗരജ്വാല സാരമായി ബാധിക്കും. നാസയുടെയും യൂറോപ്യന്‍ സ്‌പേസ് ഏജന്‍സിയുടെയും സംയുക്ത സംരംഭങ്ങളായ സോളാര്‍ ഡൈനാമിക്‌സ് ഒബ്‌സര്‍വേറ്ററിയും സോളാര്‍ ഹെലോസ്‌ഫെറിക് ഒബ്‌സര്‍വേറ്ററിയുമാണ് ശക്തമായ സൗരജ്വാലയുടെ സാന്നിധ്യം കണ്ടെത്തിയത്. സ്വൗരജ്വാല അണഞ്ഞാലും അതിന്റെ ആഘാതം ഭൂമിയെ കുറച്ചുകാലംകൂടി ബാധിക്കുമെന്നാണ് ശാസ്ത്രജ്ഞര്‍ കരുതുന്നത്. 11 വര്‍ഷത്തെ ഇടവേളയില്‍ സൂര്യനില്‍ ശക്തമായ സൗരജ്വാലകളുണ്ടാകാറുണ്ട്. ഭൂമിയേക്കാള്‍ 14 മടങ്ങുവരെ വലിപ്പമുള്ള ജ്വാലകള്‍ സൂര്യനിലുണ്ടായതായി രേഖപ്പെടുത്തിയിട്ടുണ്ട്.

പ്രൊഫ്‌. ജോണ്‍ കുരാക്കാർ