What's New :
Open Webinar for Mains 2021 : Register Now

Auroras

  • Category
    Environment
  • Published
    28th Mar, 2019

Geostorm offers Northern USA rare chance to see aurora borealis.

Context

Geostorm offers Northern USA rare chance to see aurora borealis.

About

More on news

  • A solar flare that erupted on March 20 and made the National Oceanic and Atmospheric Administration to issue a G2 watch, or moderate geostorm watch.
  • The flare bends around the Earth's natural magnetic field, and slammed into the poles at either end of the planet, which supercharged the northern lights and pushed it deeper.

What is an Aurora?

  • Polar lights (auroras) are a natural phenomenon. In the North Pole, it is called an aurora borealis or northern lights. In the South Pole, it is called aurora australis or the southern lights.

What makes this happen?

  • Even though auroras are best seen at night, they are actually caused by the sun.
  • The protective magnetic field around Earth shields us from most of the energy and particles, and we don’t even notice them.
  • During coronal mass ejection (kind of solar storm) the sun burps out a huge bubble of electrified gas that can travel through space at high speeds.
  • When a solar storm comes toward earth, some of the energy and small particles can travel down the magnetic field lines at the north and south poles into upper Earth’s atmosphere.

Do other Planets get auroras?

  • They sure do! If a planet has an atmosphere and magnetic field, they probably have auroras.
  • The gas giants in our solar system (Jupiter, Saturn, Uranus and Neptune) each have thick atmospheres and strong magnetic fields, and each have auroras — although these auroras are a little different from Earth's, given they are formed under different conditions.

What are Pulsating Auroras sometimes seen in news?

  • Sometimes on a dark night near the poles, the sky pulses a diffuse glow of green, purple and red. Unlike the long, shimmering veils of typical auroral displays, these pulsating auroras are much dimmer and less common.
  • While scientists have long known auroras to be associated with solar activity, the precise mechanism of pulsating auroras was unknown.
  • According to NASA’s THEMIS Mission and Japan’s Arase satellite mission, it is the chirping waves that rhythmically pulse the particles that create the auroras.
  • The magnetosphere is home to a type of plasma wave known as whistler mode chorus.
  • These waves have characteristic rising tones reminiscent of the sounds of chirping birds and are able to efficiently disturb the electrons.
  • When these waves make their appearance within the magnetosphere, some of the electrons scattered by the wave careen down into Earth’s atmosphere, causing the pulsating auroras.

    Magnetosphere

    • It is that area of space, around a planet, that is controlled by the planet's magnetic field.
    • The shape of the Earth's magnetosphere is the direct result of being blasted by solar wind. The solar wind compresses its sunward side to a distance of only 6 to 10 times the radius of the Earth.
    • A supersonic shock wave is created sunward of Earth called the Bow Shock.
    • Most of the solar wind particles are heated and slowed at the bow shock and detour around the Earth in the Magnetosheath.
    • The solar wind drags out the night-side magnetosphere to possibly 1000 times Earth's radius; its exact length is not known.
    • This extension of the magnetosphere is known as the Magnetotail. The outer boundary of Earth's confined geomagnetic field is called the Magnetopause.
    • The Earth's magnetosphere is a highly dynamic structure that responds dramatically to solar variations.

                                                       THEMIS MISSION

    • NASA's Time History of Events and Macroscale Interactions during Substorms (THEMIS) aims to resolve one of the oldest mysteries in space physics, namely to determine what physical process in near-Earth space initiates the violent eruptions of the aurora that occur during substorms in the Earth's magnetosphere.

                                                                Arase Mission/ERG

    • ERG is a Japanese (JAXA/ISAS) STP (Solar Terrestrial Physics) minisatellite mission into geospace focused on the formation of the radiation belts associated with magnetic storms.
    • The aim is to elucidate acceleration and loss mechanisms of relativistic particles in the inner magnetosphere during space storms.
X
Enquire Now