A solar eclipse is a natural phenomenon that happens on Earth as the Moon passes between Earth and the Sun in its orbit (this is also known as occultation). This occurs at New Moon when the Sun and Moon are together.

Solar Eclipse Facts
Image by Pete Linforth from Pixabay

If the Moon were just marginally closer to Earth, orbiting in the same plane and circular in its orbit, we would see eclipses every month. The lunar orbit is elliptical and inclined in regard to Earth’s orbit, so we can see only 5 eclipses a year. The Sun may be completely blocked, or partially blocked, depending on the geometry of the Sun, Moon, and Earth.

During an eclipse, the shadow of the Moon (divided into two parts: the dark umbra, and the lighter penumbra) passes over the surface of the Earth. Point of safety: Never look directly at the Sun during an eclipse unless it is during a total solar eclipse. The Sun’s bright light can easily do harm to your eyes.

Here are some facts about the solar eclipse: 

1. Shadows

During a solar eclipse, the shadow formed by the moon on Earth is broken down into three parts. Those are the antumbra, penumbra and umbra. The Umbra is the darkest aspect of the night, where the moon covers the sun in full. The antumbra is the field above that, where the moon is facing the Sun but doesn’t overtake it in its entirety, because the shadow isn’t as dark. The penumbra is the outer shadow area where the moon covers only a fraction of the Sky.

2. Weather

Lufft’s WS700 weather sensor reported that it was getting cloudier and windier shortly before the eclipse began. Because of light loss, the temperature dropped 4 ° C (39 ° F). With the beginning of the eclipse, the global radiation changed dramatically as shown by the WS700 measurements. Shortly before sunset, the darkness was comparable with the time.

The entire thing has been like a transition from dawn to dusk. When the moon shifts toward the sun, the sun shadow assumes the same form as the solar eclipse ‘s present one. This becomes clearly visible when holding a perforated plate, between the sun and the ground. The unique shadow on the ground looked even clearer so very fine forms could be seen.

3. Occurrence

Total solar eclipses are very rare events. On average they occur about 18 months, with reoccurrences only once every 360 to 410 years, on average, at any given location. Every year there are between 2 and 5 solar eclipses, with at least one per eclipse season. There are about 240 solar eclipses per century. The moon’s orbit is tilted relative to the Earth’s orbit around the sun, like a gyroscope, so the moon often passes beneath or above the Earth. It doesn’t cross the line between the sun and the earth at certain moments and thus does not cause a solar eclipse.

4. Visible Future

Even though the last total solar eclipse happened around midday, during the totality process, stars were visible. Nevertheless, what is to be seen in the sky is not the usual star constellation but one that will be seen in several months.  On August 21st, it corresponded to the February 2018 constellation.

5. Covers Sun Completely

The sun is 400 times larger than the moon but is fully covered during the eclipse. The closer an object is to its apparent size, the bigger it is. The Sun is about 400 times the size of the Moon, but the Moon is 400 times closer to the Earth. The consequence that they tend to be of the same size from Earth.

Different types of eclipses occur because of the various orbits: When the moon just partly covers the sun, it is considered a partial solar eclipse. When the moon passes fully in front of the sun but because of the wide distance it cannot cover it entirely, it is an Annular Eclipse. It fits exactly in the case of a total solar eclipse, so that the sun disappears entirely for a few minutes, leaving only the corona behind.

6. Total Solar Eclipse

A total solar eclipse happens when the moon blocks the solar disk entirely. During a total solar eclipse, the narrowest portion of the path is called the “zone of totality” (where the Sun is fully obscured and the Moon casts the darkest shadow (called the umbra). 

Total solar eclipses from the Earth weren’t always visible. The Moon had been too close to Earth in the past, so it totally blotted out the Sun’s disk during eclipses. The lunar orbit has shifted at a rate of just over 2 cm every year over time and, at times, the alignment is almost flawless in the new epoch.

The orbit of the Moon will, however, continue to widen, and total solar eclipses will no longer occur in maybe 600 million years. Future observers will instead only see partial and annular eclipses.

7. Annular Solar Eclipse

Not every single solar eclipse is complete. If the Moon is in its orbit further out than normal, it appears too small to cover the Sun’s disk completely. A bright ring of sunlight radiates around the Moon during such an occurrence. This type of eclipse is an eclipse which is called “annular.” It originates from the Latin word “annulus” meaning “ring.”

During such an eclipse, the time of annularity will last from 5 or 6 minutes to up to 12 minutes. Although the Sun is largely obscured by the Moon, during annularity, enough bright sunlight escapes that the observers can never directly look at the Sun. During the entire eclipse, eye protection is required.

8. Partial Solar Eclipse

A partial solar eclipse happens as Earth passes across the lunar penumbra when the Moon shifts between Earth and the Sun. Like seen from Earth, the Moon does not block the entire solar disk. Based on your location during a partial eclipse, anything from a tiny sliver of the Sun being blotted out to an almost complete eclipse could be apparent. 

Using licensed filters or an indirect viewing process, such as projecting sunlight through a telescope and onto a white piece of paper or carton, any eclipse can be viewed safely. Don’t take a telescope to look at the Sun, unless it has the correct filter. Blindness and severe harm to the eyes may result from inadequate observation techniques.

9. Magnetic Fields

Visual sunspots are magnetic fields which change the cosmic material flow. Since the sun is 149,600,000 km away from Earth, our magnetic field is influenced by geomagnetic storms on the earth. It can also impact the connectivity of aircraft or satellite, or power grids.

The magnetic geo-storms, also known as prominences, are often much larger than Earth. They consist of a hot gas loop coming from deeper levels of the sun, like 20,000 ° F hot helium caused by solar magnetic activity. Those occurrences are evident in the form of sunspots during the eclipse.

10. Won’t Last Forever

The total solar eclipse will one day expire, as the moon slowly distances itself from the earth. For about 400 Million years the distance between the moon and the sun would be too far to cover the surface of the sun completely. Solar eclipses would then be just a mystical memory.

Ashwin Khadka is a PhD Scholar in Nano Energy and Thermofluid Lab in Korea University, Republic of Korea under Korean Government Scholarship Program. He has a Masters Degree in Physics from Tribhuvan University, Kathmandu, Nepal. He is a science enthusiast, researcher and writer.