For Himmelsgucker it was the highlight of the current astronomy year 2019: The Mercury passes between Earth and Sun and can be observed with the right equipment. But in many places clouds clouded the view.
On Monday sky-gazers in Germany observed the rare spectacle of a so-called Mercury transit in front of the sun. According to the German Weather Service (DWD), however, the event was not seen in many places because of clouds and high fog. But especially in eastern Germany, there were chances for a clear view.
In a Mercury transit, the innermost planet of the solar system passes between earth and sun and can be observed with appropriate equipment as a small point in front of the solar disk. Such a constellation is rare. The several-hour event was considered the highlight of the current astronomy year 2019. In many places met sky-gazers. Observatories also opened or offered livestreams on the Internet.
In Germany, about half of the Merkur transit could be seen. The planet moved around 13.30 clock in front of the solar disk. The period of observations ended at sunset, which is currently in Germany between about 16.00 and 17.00 clock depending on the region. Until then, Mercury had only half crossed the sun.
A Mercury passage can generally only be observed with a telescope with additional special equipment or via a projection screen. Experts have been waiting vehemently before to look unprotected into the blazing sun. There is a danger of blindness. With the naked eye, the planet would not be visible in front of the sun anyway.
A Mercury transit always occurs when the Sun, Mercury and Earth are roughly in line. Mercury then passes in front of the sun when viewed from the earth and can be recognized as a tiny point. This is ultimately a kind of mini-solar eclipse.
However, the constellation rarely occurs. This is because Earth and Mercury revolve around the Sun at different speeds, and the levels of their orbits also diverge by several degrees. The next Merkurtransit comes only in 2032.
From Earth's point of view, only Mercury and Venus can pass through the Sun from all the planets in the solar system. Their orbits are closer to the sun. All other planets orbit the sun at a greater distance than Earth.