Space weather

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The term space weather is analogous to terrestrial atmospheric weather phenomena defines and describes changes in the interplanetary and interstellar medium , specifically in the near-Earth region of the magnetosphere are perceived (up to 50,000 km distance to Earth). The main causes are the solar wind and the galactic cosmic rays of the Milky Way . The Van Allen radiation belt is influenced by these influences and more matter, particle and radiation streams reach the earth's environment at irregular intervals. These influence the earth's magnetosphere, ionosphere and earth's atmosphere .

Space weather is an important research area due to its extensive effects on life on earth. The aim is to understand the underlying physical mechanisms in order to predict such events or at least to be able to recognize them in good time so that suitable protective measures can then possibly be taken.

Causes and phenomena

overview

Space weather scheme

The earth has extensive natural protective mechanisms against external influences. The magnetosphere and the earth's atmosphere act as filters for matter and radiation from space. In particular, the magnetosphere as the outermost layer represents a significant obstacle for the solar wind and directs it in a large arc around the earth. This protection is only no longer sufficient in the event of strong influences and people can feel the external factors on the earth's surface.

The structures and variability of the solar corona are considered to be the main cause of space weather . Huge amounts of matter are released through coronal mass ejections and solar flares . This creates enormous shock waves that abruptly intensify the otherwise relatively continuous solar wind that transports particles from the sun towards the earth. The solar wind therefore exerts a much greater pressure on the magnetosphere. The resulting short-term changing phenomena are known as space weather.

Eruption on the photosphere of the sun (image taken with the Hinode telescope)

Flares

A flare can be observed using optical aids as a flash of light lasting a few minutes on the sun's surface. Although the area on the sun itself is very limited, the intensity of X-rays , high-energy protons and electrons (up to about 100  MeV ) often increases by more than a thousandfold. The decay to the initial value then takes several hours. Due to the very different strength of the individual flares, these values ​​also fluctuate. If the occurrence is particularly intense, the release of gamma rays is also possible. This phenomenon is particularly evident in the years of maximum solar activity ; up to ten flares a day are then possible.

Due to the speed of light, the flares are observed from Earth with a delay of about eight minutes compared to the actual eruption. At the same time, the released radiation also arrives unhindered. The particle currents, however, follow the interplanetary magnetic field lines and therefore do not reach the earth until 10 to 30 minutes later (depending on the energy of the particles). These falling particles represent a danger for people and equipment in the upper layers of the atmosphere. X-rays can penetrate into the lowest layer of the ionosphere (about 60 to 90 km above the ground) and particles are sometimes only at an altitude of 40 to 60 km braked.

CME

Under a coronal mass ejection (engl. CME - coronal mass ejections ) refers to the ejection of large quantities of matter (several 10 billion tons) from the corona (the outermost layer of the solar atmosphere) in the surrounding space. This takes place in the form of huge gas clouds with enormous speed. In contrast to the flares, however, CMEs cannot be observed directly even with the aid of optical devices. Only the coronograph , which covers the actual solar disk in a targeted manner and only lets light from the corona through to the detector, makes this phenomenon observable. The later date of the first discovery by Richard Tousey in 1971 is due to this fact .

The material that is transported towards the earth by the solar wind is electrically charged. The interaction with the interplanetary magnetic field causes it to be severely deformed. The interplanetary magnetic field emanates from the sun and normally spreads in a spiral to the edge of the solar system due to the sun's own rotation . In relation to the earth, it is also in its orbital plane. However, this magnetic field can be rotated out of this plane by the charged particles of a CME. If a field component is created that is opposite to the field lines of the terrestrial magnetic field, a short circuit occurs on the side of the magnetosphere facing the sun and interplanetary and terrestrial magnetic fields connect. The charged particles of the CME can now penetrate the magnetosphere along the resulting common magnetic field lines and cause massive consequences. The frequency of CMEs varies with solar activity: in years of low solar activity there are only a few dozen strong CMEs; There can be more than a hundred CMEs in the active phases.

Galactic cosmic rays

Galactic cosmic rays also influence life on earth. It consists of extremely high-energy and therefore extremely fast particles (more than 1 GeV), which have their origin outside the solar system, but within the Milky Way. If these particles hit the layers surrounding the earth, then it comes to ionization of atoms and molecules in the lower stratosphere and upper troposphere at a height of 10 to 20 km. If ions grow fast enough, this could lead to the formation of condensation nuclei - the basis for cloud formation. The assumption that cosmic radiation has such an impact on earthly weather and climate has not yet been confirmed with certainty by observations. Secondary cosmic radiation is also created by particle excitation. This results in increased radiation exposure for aviation and aircraft personnel.

The intensity of the radiation fluctuates counter-cyclically to solar activity. During phases of high solar activity, stronger turbulence occurs on the solar surface. This creates shock waves from the solar plasma in interplanetary space . These shield the inner solar system in a shell-like manner and protect it from penetrating radiation. This natural protection is less in phases of low solar activity. The earth is then more exposed to cosmic rays.

Other causes

Recording of the corona

In addition to these particle and radiation flows from the sun and the Milky Way, other factors have an effect on space weather. Cosmic catastrophes in the solar system, the Milky Way or even of an extragalactic nature, such as a supernova , can also have an impact on space weather. A supernova, for example, generates very high intensities of X-rays and gamma rays. Because of their extremely high energies (> 10 20 eV), extragalactic cosmic radiation can have a particularly strong influence on earthly life. However, this factor has apparently remained relatively constant over the past millennia.

The influence of cosmic events on so-called gamma-ray bursts becomes clear . A gamma-ray burst (or gamma-ray flash) is expressed in an extremely short, very bright flash of an object, which releases enormous amounts of energy. Collisions of neutron stars and special supernovae explosions (so-called hypernovae ) are discussed as causes for this process . Although the emitted gamma radiation cannot reach the terrestrial biosphere (the atmosphere prevents the radiation from penetrating), this radiation generates toxic nitrogen oxides, which would destroy the ozone layer (see gamma flash ). If a gamma-ray burst were to take place near the solar system, the ozone layer would be destroyed for several years, which would result in considerable radiation damage to life on earth.

Effects

Maunder minimum between 1645 and 1715

Today there are many technologies that can be influenced by space weather. By destroying the on-board electronics, high-energy particle radiation can directly interrupt the transmission of TV or mobile radio satellites. The propagation conditions for the radio waves used in telecommunications and navigation systems can also worsen under the influence of space weather. According to estimates by various scientists, there should be 150 satellite failures per year on the US side alone due to the influences and changes in space weather. A coupling to interplanetary phenomena is also being investigated for the climate . There are assumptions that they could have played a regional role during the “ Little Ice Age ” in the period of the Maunder minimum from 1665 to 1715, during which time there was a correlation between low solar activity and low temperatures. However, possible modes of action are still speculative.

Electromagnetic Radiation and Magnetic Storms

Effect of the magnetosphere

Solar flares increase the flow of high-energy particles to earth. This can also interfere with electronic components on the earth's surface. The rejection rate in the manufacture of sensitive semiconductor elements during the magnetic storms is considerably higher. The impact of a CME on the earth's magnetosphere leads to the formation of geomagnetic storms . These are associated with a rapid change in the direction and strength of the magnetic field on the ground. Then in extensive electrical conductors such. B. high voltage lines or in pipelines high currents are induced. The disruption of industrial production, such as the manufacture of computer chips, breakdowns of high-voltage networks and corrosion in oil pipelines reveal considerable correlations between solar activity and the occurrence of these economic failures.

Space weather can affect modern communication systems by directly disrupting the electronic devices on board the satellites used for this purpose. Satellite communication, navigation and orientation are considerably restricted by both particle flows and fluctuating magnetic fields. Solar storms can also damage or destroy components of satellites or lead to system crashes. It is expected that this will occur particularly in satellites whose electronic components are not space hardened and which operate on low voltage in order to consume little energy. This has serious implications for telephones, television, weather forecasting and, above all, data transmissions and satellite navigation. As a result of high-energy radiation or particles, the conditions for signal propagation in the ionosphere also deteriorate. Usually the ionosphere acts like a mirror for high frequency signals (3–30 MHz) and below. However, these reflection properties change so significantly in the context of intense space influences that undesired signal overlaps can occur. In the area of ​​the upper atmosphere and ionosphere, interrupted or misdirected radio wave propagation occurs. For example, on October 29, 2003, there was a disruption of GPS reference services in Germany . E.ON Ruhrgas's ASCOS satellite positioning service also suffered an outage of several hours. Also due to the change in the terrestrial magnetic field, there was a nine-hour power failure in Québec ( Canada ) in 1989 . The causes were geomagnetically induced currents in the transmission lines and failures of power transformers .

In addition to these technical failures, the high-energy protons and electrons generated by flares and CMEs also represent a danger to living beings. In particular, astronauts and aircraft personnel as well as air travelers are exposed to increased radiation due to the altitude at which they are located. Particle concentrations, as measured after a large flare in October 1989, prove deadly even for astronauts in protective clothing. This aspect plays an important role especially during long space trips or when working outside the spacecraft. Individual, particularly high-energy particles occasionally even reach the ground and thus contribute to natural radiation exposure. Indirectly - through the resulting mutations - space weather also has an influence on the evolution of living beings. Stronger geomagnetic storms express themselves e.g. B. also in a swaying of the compass needle and lead to irritation in animals, which are guided by the magnetic field of the earth (carrier pigeons or migratory birds).

Image of the sun in the X-ray range

X-rays and gamma rays

Flares generate a much higher level of radio and X-ray radiation and thereby influence the ionosphere. Disturbances in (shortwave) radio traffic and signal reception due to increased amounts of radiation are the result. The radiation also leads to heating and thus to an expansion of the upper layers of the atmosphere. This can force satellites to make orbit corrections, Skylab crashes or the ISS.

The flux of ring current particles during magnetic storms, which is often several orders of magnitude higher, can also damage satellites, as isolated parts of the surface of a satellite can become very electrically charged and high-voltage flashovers cause defects and failures. The increased radio emissions that can be observed in connection with solar flares can also affect daily mobile phone traffic, especially in the morning and evening hours.

Northern lights

Aurora borealis

The electrons and protons of the CMEs stimulate and ionize the upper atmosphere. Northern lights are created : light phenomena especially in the area of ​​the polar ice caps; in the case of strong solar flares, however, it can also extend to northern or southern latitudes.

Cosmic rays

With its high-energy particles, cosmic rays endanger manned aerospace in particular . It represents an increased health risk (increased risk of cancer) for flight personnel and astronauts, since the aircraft are not adequately shielded from the strong galactic cosmic rays.

history

Original drawing by Carrington for the 1859 sun outbreak

The first connections between the sunspot cycle and fluctuations in global magnetism were made by observation stations of the British colonial empire. The English astronomer Richard Christopher Carrington registered the causes of magnetic storms on September 1, 1859 at the Carrington Event of 1859. Through his telescope he saw a huge explosion on the sun, which manifested itself as a very bright flash of light lasting only a few minutes (this explosion is now one of the ten strongest flares ever observed). About 20 hours later, the ejected matter and the emitted radiation reached the earth and triggered a magnetic storm that even affected the compass needles. This event can be seen as the beginning of the investigations into the solar-terrestrial relationships and space weather. Carrington suspected at this time a connection between the flares and the geomagnetic effects. However, this idea had to be revised, since the changes in the earth's magnetism are primarily due to the CMEs and the shock waves and magnetic field deflections caused by them.

In 1932, the cosmic radio emission was discovered by Karl Guthe Jansky ; ten years later the sun's radio emissions by James Stanley Hey while investigating interference with British radar stations during World War II. In the following years radio emissions were investigated in more detail using converted V2 rockets . Since the earth's atmosphere blocks a large part of the sun's radio radiation, the captured rockets were equipped with measuring instruments and shot down. Measurements could be carried out far from the ground, where the disturbing influence of the atmosphere is less.

Coronal mass ejections (CMEs) were only discovered in 1974 with the help of the Skylab space station due to poor visibility .

research

The potentially negative effects of space weather make exploring and predicting it an important part of current research. The main problem with this, however, is still a poor understanding of the basics. Since the formation of flares and CMEs is still largely unclear to this day and no reliable indications of impending eruptions and their strength are known, a prediction of space weather is hardly possible.

The entire chain of solar-terrestrial relationships is explored in many different projects:

  • A Space Weather Working Team (SWWT) was set up at ESA for this purpose, which is used to evaluate the data from the SOHO (Solar and Heliospheric Observatory) satellite .
  • The satellite cluster is supposed to research the solar activities and record the interactions between solar wind and earth's magnetic field.
  • The EUV Imaging Telescope (EIT) of the SOHO space observatory delivers images of the sun in UV light every minute, whereby structures and dynamic processes in the corona become visible and protuberances , flares, active areas, sunspots , magnetic fine structures, etc. can be examined.
  • LASCO (Large Angle and Spectroscopic Coronograph) observes the entire area around the sun, from the edge of the sun to a distance of 32 solar radii. It is thus possible to observe CMEs and Halo CMEs, which move precisely on the sun-earth line. With LASCO, important advances in research have been made with greater accuracy in predictions and better estimates of the duration of events to earth.
  • The Deep Space Climate Observatory is intended to provide NOAA and the US Air Force with data on space weather and also enable warnings of geomagnetic storms with an advance warning time of 15 to 60 minutes.

Further measurements of the solar wind, high-energy particles and the radiation flux from outside the magnetosphere as well as other particles and currents were carried out with the help of radar devices and thus fundamental effects on the ionosphere and atmosphere were investigated.

The solar-terrestrial relationships are almost completely covered by suitable observations with the help of space probes, earth satellites and ground-based measuring systems. Most of the data even appears on the Internet in near real time and is publicly accessible. Several industrialized countries use them for their official warning centers for observation and forecasting.

One problem with space weather forecasting is the short warning times, namely the time from observing the sun to reaching the earth. For example, the X-ray radiation emitted by flares is as fast as the optical information, i.e. as the observation itself. With energetic particles there is a delay of 10 to 30 minutes and with geomagnetic storms through CMEs one has at least 2 to 4 days for warning.

Ion storm prediction

Today the ion storms, which are particularly dangerous for astronauts, can be predicted more precisely. It was previously known that an ion current in solar eruptions is preceded by an increased number of electrons. However, a reliable prediction was difficult because an increase in electrons did not always result in a dangerous ion storm. Using data from SOHO, it has now been possible to develop prediction software that enables advance warning times of up to 74 minutes.

literature

  • Gerd W. Prölss: Physics of near-earth space. An introduction . Springer, Berlin 2004, ISBN 3-540-40088-5 .
  • Ioannis. A. Daglis (Ed.): Effects of Space Weather on Technology Infrastructure. Proceedings of the NATO ARW . Springer Netherlands, 2005, ISBN 1-4020-2747-8 .
  • Barbara B. Poppe, Kristen P. Jorden: Sentinels of the Sun: Forecasting Space Weather. Johnson Books, 2006, ISBN 1-55566-379-6 .
  • Volker Bothmer, Ioannis A. Daglis: Space Weather: Physics and Effects. Springer Verlag, Heidelberg 2007, ISBN 3-540-34578-7 .
  • Yohsuke Kamide, Abraham C.-L. Chian: Handbook of the Solar-Terrestrial Environment. Springer, Berlin 2007, ISBN 3-540-46314-3 .
  • Arnold Hanslmeier : The Sun and Space Weather. Springer, Dordrecht 2007, ISBN 978-1-4020-5603-1 .
  • Mark Moldwin: An introduction to space weather. Cambridge University Press, Cambridge MA 2008, ISBN 978-0-521-86149-6 .
  • Karl-Heinz Glassmeier, Joachim Vogt: Magnetic polarity transitions and biospheric effects. Space Sci. Rev., 155, 387-410, 2010.

Web links

Video

Individual evidence

  1. ^ RA Howard: A Historical Perspective on Coronal Mass Ejections . In: Natchimuthukonar Gopalswamy, Richard Mewaldt, Jarmo Torsti (eds.): Solar Eruptions and Energetic Particles Vol. 16. American Geophysical Union , 2006, ISBN 978-0-87590-430-6 , DOI doi.org/10.1029/165GM03 ( to the article ; PDF; 0.2 MB)
  2. ↑ SOHO LASCO CME catalog
  3. ^ H. Cremades, V. Bothmer: On the three-dimensional configuration of coronal mass ejections In: Astronomy and Astrophysics 422/2004. EDP ​​Sciences, pp. 307-322, ISSN  0004-6361 , on the article
  4. ^ Franck Arnold: Clouds under cosmic influence . In: MaxPlanckForschung 1/2003, pp. 7–8, ISSN  0341-7727
  5. ↑ Benjamin A. Laken et al .: A cosmic ray-climate link and cloud observations . In: J. Space Weather Space Clim. tape 2 , 2012, doi : 10.1051 / swsc / 2012018 .
  6. ↑ a b R. Schwenn, K. Schlegel: Solar wind and space weather . In: Spectrum of Science Dossier - Die Trabanten der Sonne 3/2001, pp. 15–23, ISSN  0947-7934 ( on the article ( Memento from June 10, 2007 in the Internet Archive ); PDF; 0.4 MB)
  7. ^ Willie Wei-Hock Soon and Steven H. Yaskell: The Maunder Minimum and the Variable Sun-Earth Connection , World Scientific, 2003, ISBN 981-238-274-7
  8. ↑ Tony Phillips: Solar Variability and Terrestrial Climate. In: NASA Science News. January 8, 2013, accessed September 20, 2016 .
  9. ↑ Thomas Bührke: Beyond the Milky Way . Special issue of the BMBF (2000; for the article ; PDF 1 MB)
  10. ↑ F. Kneer et al. (Ed.): Perspectives on research into the sun and the heliosphere in Germany , Copernicus GmbH, Katlenburg-Lindau 2003, ISBN 3-936586-19-5 ( to the article ; PDF; 4 MB)
  11. ↑ Thomas Weyrauch: Can a solar storm freeze electronics? , in Raumfahrer.net, Date: September 6, 2012, accessed: September 7, 2012 ( to the article )
  12. ↑ Space weather: DLR researchers expect new insights into the effects of the solar wind , DLR communication dated October 30, 2003
  13. ↑ ESA: Space Weather: Dangers to Earth , Information from November 15, 2002
  14. ↑ Cosmic Radiation - Messengers from Space ( Memento from October 30, 2018 in the Internet Archive ) (PDF; 3 MB), lecture by Dr. B. Pfeiffer (University of Mainz)
  15. ^ Space Weather Research Explorer ( Memento from September 27, 2007 in the Internet Archive ), information from the Exploratorium
  16. ↑ Course correction: Atlantis brings ISS into higher orbit. Spiegel Online , May 24, 2000.
  17. ↑ K. Scherer, H. Fichtner: The climate from space . In Physik Journal , 3/2007, Wiley-CH, pp. 59–63, ISSN  1617-9439 ( to the article ; PDF; 8 MB)
  18. ^ RC Carrington: Description of a Singular Appearance seen in the Sun on September 1, 1859 . In: Monthly Notices of the Royal Astronomical Society 20/1859, pp. 13–15, ISSN  0035-8711 ( to the article )
  19. ^ MA Shea, DF Smart: Compendium of the eight articles on the “Carrington Event” attributed to or written by Elias Loomis in the American Journal of Science, 1859–1861 . In: Advances in Space Research , 38/2/2006, pp. 313-385, ISSN  0273-1177 , doi : 10.1016 / j.asr.2006.07.005 .
  20. ^ B. Lovell: The Emergence of Radio Astronomy in the UK after World-War . In: Quarterly Journal of the Royal Astronomical Society 28/1/1987, pp. 1-9, bibcode : 1987QJRAS..28 .... 1L
  21. ↑ RM MacQueen, JR Eddy, JT Gosling et al .: The outer Solar Corona as observed from Skylab : Preliminary Results . In: Astrophysical Journal , 187/1974, pp. L85-L88, bibcode : 1974ApJ ... 187L..85M
  22. ↑ DSCOVR: Deep Space Climate Observatory | NOAA National Environmental Satellite, Data, and Information Service (NESDIS). National Oceanic and Atmospheric Administration (NOAA), accessed September 3, 2019 .
  23. ↑ Press release Science @ NASA ( Memento from August 27, 2007 in the Internet Archive ) from NASA on the new forecast software from May 25, 2007
This version was added to the list of articles worth reading on September 20, 2007 .