Найдавніші датовані малюнки сонячних плям на основі спостережень Йоганна Кеплера за допомогою камери-обскури у травні 1607 року
Astronomers have used observations by a 17th-century German mathematician to determine the state of the solar cycle in 1607, which may help solve the mystery of the period of minimum solar activity.
An international team of scientists has deciphered 400-year-old astronomical drawings, helping to unravel the mystery of solar activity at the time. The researchers used the observations of German mathematician Johannes Kepler, made in 1607, to determine the state of the 11-year cycle of the Sun.
Johannes Kepler, born in 1571, is primarily known as the author of the laws of planetary motion. However, his contribution to astronomy is not limited to this. Kepler also made careful observations of the Sun using a primitive but effective method.
To observe the Sun, Kepler used camera obscura. This is a simple device consisting of a small hole in the wall through which sunlight passes and falls on a sheet of paper. This way, the scientist could safely study the image of the Sun and sketch its features.
The dark spots that Kepler recorded on the surface of the Sun are actually temporary phenomena in the photosphere — the visible layer of the solar atmosphere. These areas appear darker because their temperature is lower than the surrounding temperature — about 3800 K (3500°C) versus 6000 K (5700°C). The spots are caused by the complex interaction of the Sun’s magnetic field with its plasma as the star rotates.
A group of researchers led by Hisashi Hayakawa from Nagoya University (Japan) applied modern methods of analyzing Kepler’s drawings. The scientists used Sperer’s law, which describes the change in the latitude of the formation of active regions of the Sun during the solar cycle. The results showed that Kepler’s observations occurred at the end of the solar cycle, which preceded a period of significant solar decline.
The data obtained can help astronomers better understand long periods of minimum solar activity, in particular the so-called Maunder Minimum (1645-1715). This mysterious stage in the history of the Sun still raises many questions among experts. The new information brings scientists closer to unraveling the causes of long-term changes in the behavior of our star and their impact on the Earth’s climate.
As a reminder, archaeologists discovered traces of tungsten in the laboratory of the Danish astronomer Tycho Brahe, although this element was officially discovered only in the 18th century.
Source: Sciencealert, Universetoday