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Observers of a total solar eclipse in Exmouth in Western Australia in April 2023
Photo: Aaron Bunch / AP
On Monday, April 8, millions of people in Central and North America - from Mexico to Canada - will be able to witness a total solar eclipse in the sky, known as SoFi for short. The spectacle cannot be seen from Germany. Only on the western edge of Europe - in parts of Portugal, Spain, Ireland and Great Britain as well as Iceland - will the moon partially obscure the sun. This SoFi could deliver particularly dramatic images. Whether this happens can be seen in this country on a live stream or – even more impressively – in a planetarium.
During a solar eclipse, the sky suddenly darkens during the day, such as at dawn or dusk. Birds fall silent for a while and anyone standing in the path of totality - also called the "path of darkness" - can see something when the sky is clear that would otherwise remain hidden: the outer part of the sun's atmosphere, the corona, which is otherwise outshone by the sun's bright light.
What exactly happens during a solar eclipse? Where can you watch the celestial event in Germany? And when can we see the next SoFi in this country? Answers to the most important questions.
How does a solar eclipse occur?
A total solar eclipse can only be observed when the new moon passes between the sun and the earth and completely obscures the sun. During such an event, you don't look at the sun at the time of complete darkening, but rather at the moon. Onlookers on site should only watch the spectacle with special glasses that filter out sun rays that are harmful to the retina. This also applies when looking through a camera or telescope. Otherwise there is a risk of permanent damage.
The moon is between the earth and the sun during each new moon phase. However, since the moon's orbit around the Earth is slightly tilted, the moon usually does not pass directly in front of the sun, but rather above or below it. A solar eclipse can only occur when the moon crosses the plane on which the sun and the earth are located and is also in line with the two celestial bodies at that moment.
The fact that the small moon then obscures the much larger sun is due to the perspective: the sun has a diameter about 400 times larger than the moon, but is also about 400 times further away from the earth. If both are visible in the sky, they appear to be about the same size; the small moon can obscure the large sun.
This makes Earth a special case. No other rocky planet in our solar system has the right proportions for a solar eclipse: Mercury and Venus have no moons, and Mars' two satellites are far too small; they can only partially obscure the sun.
How common is a solar eclipse?
Overall, such events are not that rare. There are around two to five solar eclipses worldwide every year, but these also include partial darkenings. A total SoFi only occurs about every one to two years and can then only be seen within a small region of the world. On average, such an event can only be observed from a specific location on our planet about once every 375 years. This was last the case in Germany in August 1999; the next total solar eclipse will take place here on September 3, 2081.
Where exactly can it be seen on Monday – and what options are there from Germany?
Starting over the Pacific, the moon's umbra extends over northern Mexico, crosses the USA across 13 states from Texas diagonally northeast to Maine and finally touches southeastern Canada. Large cities such as Dallas, Indianapolis, Buffalo and Montreal are located in the zone, and a total of more than 40 million people live there.
In Germany, some observatories offer events. The Zeiss Large Planetarium in Berlin, for example, invites you to experience the solar eclipse live in 360 degrees and see detailed images of the sun in full HD. Free tickets will be available at the box office on April 8th from 6 p.m. The event will also be broadcast in the Hamburg Planetarium. Solar research experts are on site to explain what is going on. The event is chargeable.
If you don't want to leave the house, you can choose from various live streams online. The American space agency offers a handful of webcasts
NASA, including annotated versions and transmissions from several telescopes in North America. You can find a stream here:
NASA will also stream the flight of three research rockets scheduled to launch from Virginia during the eclipse. Their mission: study how the sudden decline in sunlight affects our upper atmosphere.
The National Science Foundation will also show the solar eclipse. In addition, experts talk about research into the sun and provide insight into the work with the Daniel K. Inouye Solar Telescope in Hawaii, the largest solar telescope on earth.
There are also offers from various observatories: The Lowell Observatory in Arizona, for example, transmits the view of the solar eclipse from Waco, Texas. The Exploratorium in California reports live in English and Spanish from Junction, Texas, and Torreón, Mexico.
Why could this SoFi be particularly dramatic?
The sun is particularly active at the moment - more active than it has been in two decades. Every eleven years, the sun's activity waxes and wanes as the north and south magnetic poles swap places. At the beginning of this solar cycle, activity is at its lowest, which is called the solar minimum. In the middle of the cycle, activity increases, called the solar maximum, and then falls back to minimum.
This year the sun is approaching a maximum of activity. The result: There will be more solar flares and solar storms, which could also affect this year's total solar eclipse. During the eclipse, the solar corona may look very spiky, like a "very irritable little hedgehog," solar physicist Scott McIntosh told the Washington Post.
NASA observes the special solar eclipse using aircraft and balloons, among other things. Another team of researchers is using instruments on the ground to determine the density and temperature of the corona more precisely than before. And still others want to fly a huge kite loaded with instruments more than three kilometers into the sky so that no clouds disturb the view.
How else do researchers study the sun?
Two probes - NASA's Parker Solar Probe and the European Space Agency's Solar Orbiter - are on site or on their way to the sun. They work together to solve a 65-year-old mystery: Why is the sun's outer atmosphere far hotter than its surface?
The Parker Solar Probe launched to the sun on August 12, 2018 - and penetrated further into the corona than any other device before. Only 10.5 solar radii from the sun's surface, it plunged into its outer atmosphere. That corresponds to just over seven million kilometers. For the first time from this perspective, she was able to observe how the sun ejected mass into space.
The Solar Orbiter has also been active since February 10, 2020. It is intended to photograph the star at the center of our solar system as often as possible and take high-resolution close-up photos of the polar regions
.
During the mission, the scientists involved also want to measure how solar winds are composed and what accelerates them to speeds of hundreds of kilometers per second. To do this, the Solar Orbiter should now approach the sun up to 42 million kilometers, i.e. 60 solar radii.
The Esa space mission Proba-3 is also planned. In order to research the solar corona, two satellites are to be launched into space in September and simulate a solar eclipse: The first satellite has a shield with a diameter of 1.40 meters and plays the role of the moon, which moves in front of the sun. In the darkness behind it, the second satellite can take pictures of the gases around the sun.
The aim of the Mist is also to research “gigantic waves of plasma and magnetic fields” that are thrown into space from the sun’s corona, explained Esa engineer Raphaël Rougeot at a press conference on Wednesday. These events could damage satellites and facilities on Earth, which is why researchers want to better understand them and predict them in a timely manner.
With material from dpa