There are two main types of eclipses: solar and lunar. A solar eclipse is when the Moon passes between the Earth and the Sun, and a lunar eclipse happens when the Earth passes between the Sun and the Moon, casting a shadow on the moon’s surface.
A solar eclipse can be classified as either total (the Moon completely covers the Sun) or annual (The Moon covers all but an outer ring of the Sun). This “ring of fire” occurs when the Moon is either too far from the Earth, or the Earth is too close to the Sun for the Moon to completely cover it.
June and July is eclipse season, and depending on where you are in the world, you may have an opportunity to see one of three eclipses that will take place in the coming weeks.
The phenomenon is called an annular solar eclipse. It happens when the Moon is farthest away from Earth in its orbit, and therefore appears smaller in our skies relative to the Sun.
That small difference in apparent size is what sets annular eclipses apart from full solar eclipses, when the closer position of the Moon (with its average radius of 1,800 kilometres or 1,000 miles) makes it appear to be the same size as our far larger star, which has a radius of around 696,000 kilometres (432,000 miles).
A stunning – and unusual – example of this was captured by photographer Colin Legg and astronomy student Geoff Sims in Western Australia in May 2013.
How Do Eclipses Happen?
Annular eclipses are a pretty spectacular sight because of their “ring of fire” appearance, but how does this actually come to be? The answer lies in the Earth and the Moon’s orbits.
In order for the Moon to be completely blocked by the Earth’s shadow, or for the Moon to block the Sun, it must be completely (or nearly completely) in line with both the Sun and the Earth. Every month, both a new Moon and a Full Moon occurs, which theoretically should produce an eclipse. This doesn’t happen, however, because the Moon’s orbit around the Earth is not perfectly aligned with the Earth’s orbital plane around the Sun.
The Moon’s orbit is actually tilted five degrees to the Earth’s orbit, so most of the time a new Moon will pass just above or below the Sun, and a full Moon will pass just above or below the Earth’s shadow. As such there are only two points along the Earth’s orbit where the orbital plane of the Moon and the Earth coincide, and these points are called nodes.
When the Moon happens to be at a new or full phase when it nears a node, we get an eclipse. It does not need to be a perfect alignment for an eclipse to occur- as long as a new Moon is within 18.5 degrees of a node, or a full Moon is nor more than 12.5 degrees from a node, an eclipse will take place, but the more central the Moon is to the node, the most total the eclipse will be.
Eclipse seasons last for a little over a month and are usually just under six months apart from each other. Since the nodes are not stationary points and move or “regress”, they happen earlier each year by 19 days. This means that an eclipse year is 346.6 days long. Here is a video from a 2019 solar eclipse over Asia.
This year, the midpoint of the two seasons are in June and December. In June 2020, the Moon will turn new less than nine hours after the June 20 solstice, and will sweep right in front of the Sun on June 21, creating a ring of fire solar eclipse.
The Path of the Eclipse
Sadly, North Americans will not be able to view this ring of fire eclipse. The eclipse path will start in central Africa at sunrise in the Republic of the Congo, west of the Ubangi River. It will travel northeast through parts of the Congo, Central African Republic, South Sudan, Sudan, Ethiopia, the Red Sea, Yemen, Saudi Arabia, Oman, the Gulf of Oman, Pakistan, and India.
It will then move east and southeast over China and Taiwan, to the Phillippine Sea, pass just south of Guam, then end at Sunset over the North Pacific Ocean.
The point at which the eclipse will reach its fullest will occur over Uttarakhand, in Northern India. A partial eclipse will be visible over much of Africa, Asia, and Indonesia, some of southeast Europe will see the opening stages of the eclipse after sunrise, and some of Northern Australia will catch the end just prior to sunset.
This ring of fire eclipse is actually the second of three eclipses that will take place, which is unusual because there are typically only two eclipses in one eclipse season. The first and third eclipse, however, nearly miss being eclipses at all. The central one is very close to the middle of the season, which is why there is room for three eclipses.
It is important that during the entire eclipse season you wear proper eye protection. If you are lucky enough to be in a region that will be able to view this annular eclipse, it is extremely important that you wear glasses that are meant for viewing eclipses- regular sunglasses won’t cut it. Looking directly at an eclipse without proper eye protection can severely damage your eyes.