THERE'S A HOLE IN THE SUN- NASA REVEALS

നമ്മുടെ സൂര്യന് ഏന്തു പറ്റി

                 Nasa has released a stunning video showing a square 'hole' appearing on the solar surface.The hole is clearly visible as the sun rotates, appearing to be a black abyss into the centre of the Sun.The dark square on the sun, known as a 'coronal hole,' is an area where the solar wind is streaming out of the sun at superfast speeds.A coronal hole is a large region in the corona which is less dense and is cooler than its surrounds.It appears dark in extreme ultraviolet light as there is less material to emit in these wavelengths.Such holes may appear at any time of the solar cycle but they are most common during the declining phase of the cycle.Coronal holes occur when the Sun's magnetic field is open to interplanetary space. Conversely, in regions where the solar magnetic fields loop back to the Sun forming arches, x-ray and UV images show bright areas. The brightest points in the images are generally at the top of the magnetic loops or arches.A coronal hole is an area where high-speed solar wind streams into space.

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സൂര്യനില്‍ തുളയുള്ളതായി നാസയുടെ കണ്ടെത്തല്‍. സോളര്‍ വിന്റ് എന്ന പ്രതിഭാസം അതിവേഗത്തില്‍ നടക്കുമ്പോള്‍ എടുത്ത ചിത്രങ്ങളില്‍ നിന്നാണ് നാസ ഇത് കണ്ടെത്തിയിരിക്കുന്നത്. കൊറോണല്‍ ഹോളാണ് ഇതെന്നാണ് നാസ പറയുന്നു. ഇത് സംബന്ധിച്ച വീഡിയോയും നാസ പുറത്തുവിട്ടിട്ടുണ്ട്. കൊറോണല്‍ ഹോള്‍ ചതുരാകൃതിയിലായിരിന്നു. കറുത്ത കളറില്‍ പ്രത്യക്ഷപ്പെട്ട ഈ ഹോളില്‍ വിവിധ ലൂപ്സ് കണ്ടെന്നും, ഒപ്പം പ്ലാസ്മ ഔട്ട് ലൈനുകള്‍ ഉണ്ടായതായും നാസ പറയുന്നു.

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'It appears dark in extreme ultraviolet light as there is less material to emit in these wavelengths.'Nasa also revealed the strange flickering pattern visible inside the hole were caused by giant 'strands' of plasma.'Inside the coronal hole you can see bright loops where the hot plasma outlines little pieces of the solar magnetic field sticking above the surface.'Luckily for Earth, because of the position of the hole, it is unlikely to affect us.'Because it is positioned so far south on the Sun, there is less chance that the solar wind stream will impact us here on Earth,' Nasa said.Radiation is emitted across virtually the entire electromagnetic spectrum, from radio waves at the long wavelength end, through optical emission to X-rays and gamma rays at the short wavelength end.The amount of energy released is the equivalent of millions of 100-megaton hydrogen bombs exploding at the same timeA flare occurs when magnetic energy that has built up in the solar atmosphere is suddenly released - mostly in the active regions around sunspots.

Their frequency varies from several a day, when the sun is particularly active, to less than one a week during quiet periods.The observation was all the more incredible as it was only by chance all of the observatories were looking at the same point on the sun at the same time.The flare observed was an X-class flare, the biggest and highest-energy solar flares that have ever been observed.In particular it was an X1 flare, which is the lowest intensity within the X category but significantly more powerful than the majority of flares.‘This is the most comprehensive data set ever collected by Nasa's Heliophysics Systems Observatory,’ said Jonathan Cirtain, project scientist for the joint US-Japan mission Hinode at Nasa's Marshall Space Flight Center in Huntsville, Alabama.‘Some of the spacecraft observe the whole sun all the time, but three of the observatories had coordinated in advance to focus on a specific active region of the sun.‘We need at least a day to program in observation time and the target – so it was extremely fortunate that we caught this X-class flare.’

The telescopes involved were Nasa's Interface Region Imaging Spectrograph, or Iris; Nasa's Solar Dynamics Observatory, or SDO; Nasa's Reuven Ramaty High Energy Solar Spectroscopic Imager, or Rhessi; the Japanese Aerospace Exploration Agency's Hinode; and the National Solar Observatory's Dunn Solar Telescope located at Sacramento Peak in New MexicoThis event was particularly exciting for the Nasa’s Interface Region Imaging Spectrograph (Iris) team, as this was the first X-class flare ever observed by them.Astronauts 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 charged particles can also threaten airlines by disturbing the Earth’s magnetic field.Very large flares can even create currents within electricity grids and knock out energy supplies.A positive aspect, from an aesthetic point of view, is that the auroras are enhanced.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.Where terrestrial weather watching involves thousands of sensors and innumerable thermometers, solar observations still rely on a mere handful of telescopes.The instruments on the observatories are planned so that each shows a different aspect of the flare at different heights off the sun's surface and at different temperatures.

Together the observatories can paint a three-dimensional picture of what happens during anygiven event on the sun.During this event in the space of just a few minutes, the most comprehensive flare data set of all time had been collected.Now scientists are hard at work teasing out a more detailed picture of how a flare starts and peaks - an effort that will help unravel the origins of these little-understood explosions on the sun.Such research can help scientists better understand what catalyst sets off these large explosions on the sun.

                                           പ്രൊഫ്‌.ജോണ്‍ കുരാക്കാർ