UPSC Express

Headline : Note on Solar storm

Details :

• The surface of the Sun is a very busy place.
• It has electrically charged gases that generate areas of powerful magnetic forces.
• These areas are called magnetic fields .

• The Sun’s gases are constantly moving, which tangles, stretches and twists the magnetic fields.
• This motion creates a lot of activity on the Sun’s surface, called  solar activity.
• Sometimes the Sun’s surface is very active.
• Other times, things are a bit quieter.
• The amount of solar activity changes with the stages in the solar cycle .
• Solar activity can have effects on Earth, so scientists closely monitor solar activity every day.
• Few forms of solar activities are:
• • Solar flares
  • Coronal mass ejections
  • High-speed solar wind
  • Solar energetic particles
• All these solar activities are driven by the solar magnetic field.

• Sunspots are areas that appear dark on the surface of the Sun.
• These appear dark because they are cooler than other parts of the Sun’s surface.
• The temperature of a sunspot is still very hot  that is around 6,500 degrees Fahrenheit.
• Sunspots are relatively cooler because these form at areas where magnetic fields are particularly strong.
• These magnetic fields are so strong that they keep some of the heat within the Sun from reaching the surface.

• These were first known to be occurring in 1859.
• The magnetic field lines near sunspots often tangle, cross, and reorganize.
• This can cause a sudden explosion of energy called a  solar flare.
• More sunspots lead to more frequently occurring solar flares.
• Solar flares release a lot of radiation into space.
• Flares are the largest explosive events of our solar system.
• These are seen as bright areas on the sun and these can last from minutes to hours.
• Solar flare is seen by the photons (or light) it releases, at almost every wavelength of the spectrum.
• Flares are also sites where particles (electrons, protons, and heavier particles) are accelerated.
• Solar flares are sometimes accompanied by a coronal  mass ejection (CME).
• CMEs are huge bubbles of radiation and particles from the Sun.
• These explode into space at very high speed when the Sun’s magnetic field lines suddenly reorganize.

• Solar flares cannot typically be detected by the naked eye from the surface of the earth.
• The primary ways to monitor flares are by x-rays and optical light.

• Solar flare activity can vary from several per day to only a few a month, depending mostly upon the overall activity of the Sun as a whole.
• Solar flares are typically classified as A, B, C, M or X depending upon the degree of their peak flux.

• Solar flares impact the Earth only when these occur on the side of the sun facing the Earth.
• Because flares are made of photons, these travel out directly from the flare site, so if we can see the flare, we can be impacted by it.
• When charged particles from a CME reach areas near the Earth, these can trigger intense lights in the sky, called auroras.
• Radiations released from the solar flare can:
• • Interfere with radio communications on the Earth
  • Disrupt power utility grids, which at their worst can cause electricity shortages and power outages
  • Knockout satellites
  • Effect spark stunning displays of the Northern Lights

• The Sun is a magnetic variable star at the center of our solar system that drives the space environment of the planets, including the Earth.
• The distance of the Sun from the Earth is approximately 93 million miles.
• At this distance, light travels from the Sun to the Earth in about 8 minutes and 19 seconds.
• The Sun has a diameter of about 865,000 miles, about 109 times that of Earth.
• Its mass is about 330,000 times that of Earth and accounts for about 99.86% of the total mass of the Solar System.
• About three quarters of the Sun’s mass consists of hydrogen, while the rest is mostly helium.
• Less than 2% consists of heavier elements, including oxygen, carbon, neon, iron, and others.
• The Sun is neither a solid nor a gas but is actually plasma.
• This plasma is tenuous and gaseous near the surface, but gets denser down towards the Sun’s fusion core.

• It can be divided into six layers.
• From the center out, the layers of the Sun are as follows:
• • The solar interior composed of the core (which occupies the innermost quarter or so of the Sun’s radius)
  • Radiative zone
  • Convective zone
  • Photosphere (visible surface)
  • Chromosphere
  • Corona (outermost layer)
• The energy produced through fusion in the Sun’s core powers the Sun and produces all of the heat and light that we receive here on the Earth.
• The Sun, like most stars, is a main sequence star and thus generates its energy by nuclear fusion of hydrogen nuclei into helium.
• In its core, the Sun fuses 430–600 million tons of hydrogen each second.
• The Sun’s hot corona continuously expands in space creating the solar wind, a stream of charged particles that extends to the heliopause at roughly 100 astronomical units.
• The bubble in the interstellar medium formed by the solar wind, the heliosphere, is the largest continuous structure in the Solar System.