Dhe anticipation is huge in many places: On Monday (April 8th), millions of people in Central and North America – from Mexico to Canada – can admire a total solar eclipse in the sky. At least in good weather. The astronomical spectacle cannot be observed from Europe. A partial solar eclipse can only be seen on the western edge of the continent – in parts of Portugal, Spain, Ireland and Great Britain as well as in Iceland. An overview:
What is a total solar eclipse?
A total solar eclipse occurs when the moon passes between the sun and the earth and completely obscures the sun as seen from the earth. “The sky darkens as if it were dawn or dusk,” explains the American space agency NASA. Since the moon is 400 times smaller than the sun, but also happens to be 400 times closer to the earth, both celestial bodies appear exactly the same size from our perspective. As a result, during a total eclipse, the sun's disk is darkened, but not its halo, the so-called solar corona. “Solar eclipses have a very special power,” said NASA boss Bill Nelson at a press conference. “They move people and give them a deep respect for the universe.”
Why are solar eclipses so rare?
The moon orbits the earth monthly, but lunar or solar eclipses do not occur every month. This is due to the inclination of the Moon's orbit relative to the Earth's solar orbit by about five degrees. Because of this, the moon, as seen from Earth, passes above or below the sun in most months. For the same reason, the full moon is not obscured by the Earth in a lunar eclipse every few weeks. When this happens, the moon is always in shadow when viewed from the entire side of the Earth facing the moon. However, when the Earth is darkened by the Moon, its shadow only falls on a small area. This is why you experience a lunar eclipse much more often than a solar eclipse at a particular location on Earth.
Overall, solar eclipses are not that rare. At least twice a year the moon obscures the sun somewhere in the world. But there are also years with five solar eclipses. However, this also includes partial ones. The fact that the sun is completely obscured somewhere only happens every one or two years – but it is only ever visible from a small part of the earth. On average, a total solar eclipse can only be seen from a given location on Earth about every 375 years.
However, the opportunities for this are unevenly distributed around the world. Ultimately, as a result of the not entirely circular shape of the Earth's orbit around the sun, places north of the equator are darkened twice as often as those in the southern hemisphere – on average over long periods of time and with a considerable statistical spread. The residents of Carbondale in the American state of Illinois last experienced a solar eclipse in 2017 and are now in the umbra again. In the area around what is now the city of Christchurch in New Zealand, the last time there was a solar eclipse was in 69 AD. And the next one won't happen until 2431.
What does this look like for North America – and what for Germany?
The last total solar eclipse was visible from the territory of the USA in 2017, from Mexico in 1991 and from Canada in 1979. The next one – after the one on April 8th – for the USA and Canada will not occur again until 2044, for Mexico in 2052. The last time a total solar eclipse was seen in Germany was in August 1999; the next one will take place on September 3, 2081.
Where exactly can the total solar eclipse on April 8th be observed from?
Starting over the Pacific, the umbra extends over northern Mexico, crosses the USA across 13 states from Texas diagonally northeast to Maine and finally touches southeastern Canada. The spectacle mainly takes place in the afternoon local time. Large cities such as Dallas, Indianapolis, Buffalo and Montreal are located in the zone, and a total of more than 30 million people live there.
What are the preparations like?
Institutions like NASA and astronomy enthusiasts in North America have been planning for the day of the solar eclipse for months. In many places, parties for watching together are planned, at which special glasses to protect the eyes will be distributed free of charge. Numerous schools in districts from which the total solar eclipse can be viewed have announced that they will close on the day. In addition, millions of people who live elsewhere have booked trips. Hotels and holiday apartments in the areas with a total solar eclipse are fully booked in many places, and the authorities warn of very high traffic volumes.
Mexican President Andrés Manuel López Obrador even moved his daily meeting with the security cabinet at 6 a.m. and his usual press conference to the northwestern coastal city of Mazatlán in Sinaloa state – only to put on safety glasses and observe the phenomenon afterwards. “This is something you don’t see every day, and it’s important for everyone,” López Obrador said. As a child he was fascinated by a comet. You never forget that.
Many scientists are also prepared. The event is a “wonderful opportunity for scientific research,” said NASA boss Nelson. The American space agency observes, records and measures the solar eclipse using aircraft, balloons and observatories on Earth, among other things. According to NASA, astronauts on the International Space Station (ISS) can also observe the spectacle.
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