Six Facts About Solar Eclipses

A solar eclipse is when the Moon passes directly between the Earth and the Sun, which results in a total or partial obscuring of the Earth’s view of the Sun. During this period, a large shadow is cast on some regions of the Earth. For example, on Monday, 21st of August 2017, the Moon fully occulted the Sun in the United States.

This rare event lasted for 90 minutes in total and spanned 14 states – from West Coast to East Coast.

When the eclipse occurred, the corona appeared like a ring around the Moon completely covering the Sun (totality). When totality occurs, a 200-km-wide core shadow was observed. This only happens during a total eclipse like the one that happened on August 21st, 2017. The next one to take place with a similar route will take place in 94 years.

Image Credit: Shutterstock / Allexxandar

The Event was Live-Streamed by Exploratorium and NASA

To assess the total eclipse, the sun spots and the corona, various NASA telescopes were in operation in Madras, Oregon, and Casper, Wyoming. With a hydrogen light telescope, for example, the Exploratorium crew was able to observe the Sun’s outermost atmosphere.

In Madras, a Lufft WS700 multi-parameter weather sensor was deployed to observe the weather parameters; air pressure, temperature, precipitation intensity, precipitation type, precipitation quantity, relative humidity, wind direction, wind speed, and radiation.

Fact 1: The Weather Noticeably Changes During a Solar Eclipse

Lufft‘s weather sensor WS700 recorded cloudier and windier weather shortly before the eclipse began. There was a temperature drop of around 4 °C (7 °F) due to light loss. The global radiation significantly shifted at the start of the eclipse, as recorded by the measurements of the WS700.

The darkness could be compared to that of the time shortly before sunset. The entire process was like an instant change from daylight to twilight. As the Moon passes in front of the Sun, the shadow of the Sun takes the same form as the current one of the solar eclipse.

This becomes visible when taking a perforated plate and holding it between the Sun and the ground. The unique shadow appears even sharper on the ground, so it is possible to see very fine shapes.

Fact 2: Solar Eclipses do Not Occur Every Month Even Though the Moon Seems to Take the Same Path

The Moon’s orbit is tilted relative to the orbit of the Earth around the Sun, much like a Gyroscope, so the Moon typically crosses below or above the Earth. At that time, it does not pass the line between the Sun and the Earth and therefore does not generate a solar eclipse: A solar eclipse is only possible twice a year.

Find the full explanation in the video below from the Exploratorium:

Video Credit: Exploratorium

Fact 3: The Sun is 400 Times Larger Than the Moon But Gets Covered Completely

The closer an object becomes, the bigger it appears. The Sun is roughly 400 times larger than the Moon, but the Moon is around 400 times closer to the Earth. This means that from Earth, they seem to be equal in size.

Due to the different orbits, various types of eclipses occur: If the Moon only partially covers the Sun, it is called a partial solar eclipse. If the Moon moves completely in front of the Sun but cannot cover it completely due to the excess distance, it is an Annular Eclipse. 

Only in the case of a total solar eclipse does everything align perfectly so that the Sun completely disappears for a few minutes, leaving only its corona visible.

Fact 4: During an Eclipse, You Can Look Into the Future

Although the previous total solar eclipse took place around midday, there were stars visible during the phase of totality – as at night. However, it is not the standard stellar constellation as expected, but rather one that will be seen in several months’ time. On the 21st of August, it aligned with the constellation of February 2018.

Fact 5: Visible Sunspots are Magnetic Fields Changing the Flow of Cosmic Material

Although the distance between the Sun and Earth is a whopping 149,600,000 km, geomagnetic storms on the Sun have a real influence on the Earth’s magnetic field. This can have a direct impact on airplane or satellite communications or even power grids.

The geomagnetic storms, also known as prominences, are generally much larger than the Earth. They are comprised of a loop of hot gas emanating from deep sun layers, such as 20,000 °F hot helium as a result of solar magnetic activity. When a solar eclipse occurs, these events become visible in form of sunspots.

Fact 6: Solar Eclipse Events Will Not Happen Forever

In around 400 Million years, as the Moon slowly distances itself from the Earth, the event of a total solar eclipse will no longer occur. This is because the distance between the Moon and the Sun will be too great to completely cover the Sun’s disk. When this is the case, solar eclipses will only be a distant memory in the cosmic consciousness.

Learn More About this Event in the Video of the Exploratorium in Cooperation with NASA:

LIVE REPLAY Total Solar Eclipse 2017 | Telescope and Program from Madras, OR and Casper, WY

Video Credit: Exploratorium

This information has been sourced, reviewed and adapted from materials provided by OTT HydroMet.

Lufft and Kipp & Zonen are two of OTT HydroMet's strong brands for professional environmental monitoring. For more information on this source, please visit OTT HydroMet.


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