Solar Flare – How it can affect our earth?
There has been a lot of talk about solar cycle 24 because its related to 2012. Well what do you think that it would happen?. That is a whole different topic and its full of uncertainties. Lets talk purely scientifically, the solar cycle 24 officially started Jan. 10, 2008 when reversed-polarity sunspot appeared—and this signals the start of Solar Cycle 24,” says David Hathaway of the Marshall Space Flight Center.
the first sun spot seen that started the Solar Cycle 24
Now what does the solar cycle mean?
Period in which several important kinds of solar activity repeat, discovered in 1843 by Samuel Heinrich Schwabe (1789 – 1875). Lasting about 22 years on average, it includes two 11-year cycles of sunspot’s, whose magnetic polarities alternate between the Sun’s northern and southern hemispheres, and two peaks and two declines in the phenomena (e.g., solar-prominence, auroras) that vary in the same period. Attempts have been made to connect the solar cycle to various other phenomena, including possible slight variations in the diameter of the Sun, sequences of annual growth rings in trees, and even the stock market’s rise and fall.
Areas on the Sun near sunspots often flare up, heating material to millions of degrees in just seconds and blasting billions of tons of material into space. The precise causes of solar flares and coronal mass ejections is another one of the great solar mysteries. Here again, we now know many details about these explosive events and we understand the basic mechanisms, but many details are missing. We still cannot reliably predict when and where a flare will occur or how big it will be. This problem is a little like trying to predict tornadoes.
how it can affect our earth?
there are has been many theories to this but
Surface Waves and Helioseismology
Patches of the surface of the sun oscillate up and down with a typical period of about 5 minutes. The nature and source of these “5-minute oscillations” was a mystery for many years after their discovery in 1962. These oscillations are shown in the image on the left as areas of blue and red where the blue areas are moving toward us (blue-shifted) and the red areas are moving away from us (red-shifted). The fact that this signal is strongest near the center of the imaged disk of the sun and weakest near the edge indicates that the motions are primarily radial – inward and outward. A movie (3.7Mb MPEG)constructed from a series of these images (taken at the rate of one per minute for 150 minutes with the GONG network instruments) shows how individual patches are blue-shifted and then red-shifted through several cycles. The result is an apparent chaotic vibration of the sun.
The mysterious source of these oscillations was identified by way of theoretical arguments in 1970 and confirmed by observations in 1975. The oscillations we see on the surface are due to sound waves generated and trapped inside the sun. Sound waves are produced by pressure fluctuations in the turbulent convective motions of the sun’s interior. As the waves move outward they reflect off of the sun’s surface (thephotosphere) where the density and pressure decrease rapidly. Inward moving waves are refracted (their direction of motion bent) by the increase in the speed of sound as the temperature increases and eventually return to the surface. These trapped sound waves set the sun vibrating in millions of different patterns or modes (3.7 Mb MPEG movie). Since sound is produced by pressure, these modes of vibration are called pmodes. One mode of vibration is shown in the image above as a pattern of surface displacements exaggerated by over 1000 times. A movie (1Mb MPEG without audio, 6.5 Mb MPEG version with audio) shows how this mode of oscillation consists of two opposite moving waves.
These sound waves, and the modes of vibration they produce, can be used to probe the interior of the sun the same way that geologists uses seismic waves from earthquakes to probe the inside of the earth. Some of these waves travel right through the center of the sun. Others are bent back toward the surface at shallow depths. Helioseismologists can use the properties of these waves to determine the temperature, density, composition, and motion of the interior of the sun. A number of fascinating discoveries have been made in the last few years using the science of helioseismology. The image above (from M. J. Thompson) shows the internal rotation rate of the sun with red for fast and blue for slow. The variation we see at the surface between the equator and the poles extends inward and then rapidly disappears at the base of the convection zone (shown by the dashed line).
the above part is taken from http://solarscience.msfc.nasa.gov/Helioseismology.shtml
well Helioseismology can affect our earth but the main concern is the “weakening of Earth’s Magnetic Field”
The solar winds
The solar wind is a stream of charged particles which is ejected from the upper atmosphere of the sun. it mostly consists of protons and electrons. The energy is about 10 to 100 Kev. The stream of particles varies with temperature and the speed over time. These particles escape from the sun’s gravity because of their high kinetic energy and high temperature of the corona.
The earth’s magnetic field or magnetosphere protects us from most of solar wind and solar storms. The solar wind creates a heliosphere, a vast bubble in the interstellar medium that surrounds the solar system.
It’s responsible for the geomagnetic storm that can knockout the power grids on earth.
Auroras(the northern and southern lights) are created due to the striking of solar winds to the magnetic field of the earth.
The protons and neutrons can be measured on earth. The speed of the solar wind is also an important data which are measured by the observatories like solar observatory and helioscopic observatory. These solar winds can predict the classes of the solar flares.
these are the images of various sun spot observed.