In 1995, NASA and ESA (European Space Agency) launched into space satellite SOHO ( Solar and Heliospheric Observatory ), an ambitious mission that aimed to study the Sun at a level of detail never achieved before. Located in the Lagrangian point L1 (a point between the Earth and Sun gravitational stability, located 1.5 million km from our planet), its task would be to study the star continuously observing its outermost layer, the solar wind and studying its internal structure by using heliosismología.
SOHO observations have helped change the way scientists view the Sun. The star is very important for life on Earth, but it was one of the great unknown and kept many unknowns that later missions such as SOHO andSTEREO or SDO have largely been resolved.He has captured some spectacular images of the star.
1. Space Weather Prediction
Space weather is one of the aspects of the study of the inner solar system that has gained more attention in recent years. Solar storms cause not only beautiful light shows in the polar skies but can cause major breakdowns in communication satellites and if they are really powerful in the electric network of some countries, as happened in Canada in 1989 . The eruptions on the surface of the Sun and coronal mass ejections (as the image) launch into space a flow of electrically charged plasma that reaches Earth in about eight minutes particles, which is very little time to take action if the eruption It has been particularly intense.SOHO has enabled predictions can be made up to three days in advance.
2. Eleven years of activity
One of the main advantages of SOHO is that, by bringing nearly twenty years observing the Sun, has been studying almost two cycles of activity nearly complete.These cycles of eleven-year marked by the appearance in Star darker regions known as sunspots, and traverse points minimum and maximum activity in which there are more (or less) eruptions, for example, and geomagnetic storms that cause auroras.The solar cycle was discovered in 1834 by Samuel Heinrich Schwabe.
3. Thousands of new comets
SOHO has an instrument, the coronagraph, which blocks the sun to study the corona, which is the outermost layer of its atmosphere. What scientists did not expect is that, that way, the observatory could discover almost 3,000 new comets since 1996. These comets are of the ” sun grazer “Or what is the same, flush the Sun, discovered by Heinrich Kreutz.Their orbits take them to pass so close to the star, many of them just disintegrated.SOHO participated, for example, last year ‘s campaign observation of Comet ISON, who was expected to offer a great show while visiting around the Earth that did not quite happen.
4. CMEs in detail
The CME or coronal mass ejections are huge bubbles of gas released by the Sun for several hours.Woven into them they are also lines of the magnetic field of the sun, and their emissions are attached to the solar wind.In times of increased activity of the star, you can eject three CMEs a day, and all that electromagnetic radiation affects the inner solar system.SOHO has allowed to study in greater detail than hitherto, noting their origin in solar active regions, and allowing a better understanding of how the charged particles thrown at them affect our planet.They are the ones that can cause interference in satellite communications and be harmful to especial eye Astronauts on the International Space Station or on any mission in Earth orbit.
5. Solar flares
The satellite has helped heliophysics can better differentiate coronal mass ejections of solar flares, which are not always related.The latter are quick and intense variations in the brightness of the sun, like flashes produced by the release of electromagnetic energy in the loops formed in the magnetic field of the star.These flares are classified into three types according to their intensity ; C, M, and X, the latter being the most powerful and those most likely to have some effect on Earth.Sometimes these are noted in radio interference.
6. The interior of the Sun.
Helioseismology studying the propagation of acoustic waves through the Sun for information on its interior, similar to what happens on Earth with earthquakes way, and is the method using SOHO to unravel the mechanisms and the internal structure of the star .Detecting the movements of these acoustic waves (such as rhythmic oscillations caused by changes in solar brightness), SOHO has been discovered that in the red layers of the image above, the sound moves faster than scientists had theorized, which means that the temperature is higher.For example, the most intense red layer near its center shows an unexpected peak temperature in the transition area between the convection zone (the outermost part of the sun and turbulent) and radiative (the more stable internal region).These violent changes in temperature are one of the aspects that most intrigues heliophysics.
7. The Dark Side of the Sun
The study of the propagation of acoustic waves inside the sun can also get an idea of the activity in the hemisphere that the star hides from us in every moment of their rotation. SOHO data provide images that can be generated, for example, sunspots appearing on the far side and when that side finally comes face to Earth, you can check whether these spots are of novelty there.Given that the activity in these eruptions can generate plasma, it is very useful in the study of space weather.
And we spoke of sunspots, the continued observation of the Sun that SOHO has been doing for 19 years has allowed to obtain a complete picture of the evolution of sunspots , regions of activity that appear on the surface of the star and mark the initiation of a cycle of activity.Some can reach a size of thirteen times the size of Earth, and the image (captured in 2001), and also generate both flares and coronal mass ejections.These sunspots are seen darker because they are relatively cooler than their surroundings and are formed by magnetic activity on the sun’s interior.
9. The solar wind
All the stars launch the space plasma flows known as “The wind”. The Sun is no exception, emitting it from the upper layers of the atmosphere. The solar wind consists of charged particles at very high energies and extends throughout the heliosphere, which is the area of influence of the star and covering the entire solar system.Scientists have tried for years to find its point of origin, which SOHO was able to observe darker areas in the polar regions of the corona, called coronal holes.For them escaping oxygen atoms with very high temperatures, which are then accelerated to supersonic speeds equivalent to 1.5 solar radii area, and the flow of particles from the solar wind.The fastest, at least.
10. The burning crown
The corona, the outermost part of the sun’s atmosphere, has always greatly intrigued scientists.Visible only during total eclipses (when the moon blocks the star), its temperature is extremely higher than the photosphere, or visible solar surface, reaching millions of degrees Kelvin without knowing why.SOHO’s coronagraph has the opportunity to better study the solar corona, and has even offered a plausible explanation for this warming.Scientists believe that the transfer of magnetic energy into the outer layers of the atmosphere of the star could be responsible for the crown is up to 300 times hotter queue surface.
11. The total irradiance of the Sun
The irradiance is the energy per unit area on Earth produced by the Sun in the form of electromagnetic radiation (light that we perceive, basically). Its measurement can help better understand the relationship between the sun and our planet , and how variations in emissions can affect the atmosphere, magnetosphere and, ultimately, to the surface.
12. Thus the sounds Sol
The observations of the acoustic waves passing through the Sun not only serve to take a look inside, but also to”listen” to the star .The video above is made by attaching data SOHO and SDO (Solar Dynamics Observatory ) line of hydrogen in the Sun’s spectrum, and is one of many examples of data captured by special probes that can be translated into sound.The Cassini mission, for example, has studied emissions within the rings of Saturn, and NASA’s has “translated” so that we can hear them.
13. A turbulent magnetic field
The Sun’s magnetic field is an issue that not only studied SOHO, but other missions launched subsequently, since much of their activity is determined by magnetic processes originated under its visible surface .SOHO has observed, for example, the magnetic activity that causes the appearance of sunspots in the photosphere, in addition to studying the solar dynamo that generates its magnetic field.It is an extremely complex and still are being explored new ways and deepen the already known theme.
14. Transits of Venus and Mercury
The transits of the inner planets (Venus and Mercury) across the Sun were used in ancient times to measure the distance between them and Earth. Currently, no longer have much scientific interest, but represent good viewing opportunities for the general public and are often used to test the instruments and imaging spectrographs from satellites observing the sun. In addition, the method of Traffic is one of the most widely used to discover new extrasolar planets , and even try to study their atmospheres.