Aurora Borealis over Poland as in the far north
The Sun is getting restless. It is approaching the next maximum of its activity cycle. The enormous amounts of energy stored in the magnetic field of it are converted into violent phenomena such as flares and coronal mass ejections. The events do affect the Earth and one of them took place on the night of April 23/24.
The sun, through its activity, shapes the conditions prevailing in interplanetary space, also near the Earth. The state of these conditions is called space weather. High-energy radiation (e.g. X-rays) emitted by the Sun as well as plasma clouds and charged particles ejected by the Sun with great speed have a significant impact on the condition of the Earth’s atmosphere and magnetosphere.
Extreme space weather conditions occur during strong flares and coronal mass ejections. As a result, there is a strong disturbance of the upper atmosphere (increase in the degree of ionization) and the magnetosphere (geomagnetic storms and stronger radiation belts). The effect of these phenomena may be interference in radio communication (terrestrial and satellite), damage to power grids, to satellites and unfavorable changes in their orbits. Astronauts are also exposed to higher levels of dangerous radiation.
One manifestation of extreme space weather is the extensive and bright aurora borealis. The auroral glow is caused by atoms of matter ejected from the Sun that hit the Earth’s atmosphere. In calm conditions, the visibility of the aurora is limited to the polar regions. However, when a faster and denser cloud of material ejected from the Sun reaches the Earth, the aurora can become brighter and reach lower latitudes. In such cases, we have a chance to see the aurora from Poland. It is usually visible quite low above the northern horizon in the form of a diffuse red or green glow. The aurora that occurred on the night of April 23/24 was thus unusual.
Two days before the auroral night, on April 21, the Sun experienced a solar flare accompanied by a coronal mass ejection. After more than 2 days of propagation through interplanetary space at a speed of over 800 km/s, the ejection reached the Earth. Its interaction with the Earth’s magnetosphere caused a strong geomagnetic storm. One of the effects of this event was a very bright and extensive aurora that occurred on the night of April 23/24. It was visible not only in the polar regions but also far from them, for example in Spain (photo). In Poland, it covered a large area of the sky, reaching up to the zenith. This happened probably for the first time in 20 years. We could see such a bright and extensive aurora in 2003.
Unfortunately, in the western part of Poland clouds interrupted observations, but the aurora was recorded by three ALPS stations located in the observatories in Ostrowik, Sopotnia Wielka, and Piwnice. In the first two places, the weather was very favorable, in the third only a fragment of the aurora was visible in the spaces between the clouds.
To readers interested in a detailed description of the aurora and the phenomena that led to it, we recommend the text on Polish AstroBloger.
ALPS (All-sky Light Pollution Survey) is a network of automatic light pollution monitoring stations. The project is coordinated by the Astronomical Institute of the University of Wrocław – project website. The field of view of the ALPS cameras covers almost the entire sky. South is at the bottom of the frame, north at the top, east to the left, and west to the right. In the center of the field of view is the zenith which is the point of the sky directly above the camera.
text: dr Sylwester Kołomański, head of the ALPS project
Department of Heliophysics and Space Physics, Astronomical Institute, Faculty of Physics and Astronomy
University of Wrocław
Translated by Milena Topolska (student of English Studies at the University of Wrocław) as part of the translation practice.
