What is an Eclipse?
In spite of everything I try to do with Science Avenue—in spite of all of the stigmas I hope to subvert, in spite of all of the misconceptions I hope to disprove, and in spite of all of the good I try to accomplish—the column’s central theme remains incredibly one-sided. In short, science is really cool, and sometimes, the only excuse one needs to learn more about a thing is precisely because that thing incites wonder and amazement. To fully appreciate science—to truly bask in the wonder of our universe—does not require a bachelor’s or a master’s or a doctorate. Our universe is pretty cool on its own, and the fact that we can even begin to try to explain a mere infinitesimal atom of this 13.8 billion-year-old space is wondrous—regardless of age, persuasion, or educational background.
This is all to say that eclipses are really cool, and if I can convince even one person of their coolness, then Science Avenue’s prime directive will have been fulfilled.
An eclipse is a syzygy—a straight-line configuration of three celestial bodies where one body is positioned directly in front of another body that is positioned directly in front of another body.
How does an Eclipse work?
Even though eclipses require any three astronomical bodies, we typically think of eclipses as either solar or lunar. Solar eclipses are the most commonly known eclipses. They occur when the Moon is positioned between the Earth and sun, such that the moon appears to completely cover the sun. In comparison, lunar eclipses occur when the Earth itself acts as an occluding body, positioned between the sun and the moon.
The last lunar eclipse to take place was on Sept. 27, 2015. For those who were fortunate enough to view the eclipse, the moon most likely appeared reddish-brown. This is a result of the Earth blocking the sun’s light. There was light from the sun hitting the moon, but the light was refracted through the Earth’s shadow, as a result of a phenomenon known as Rayleigh scattering.
Science Avenue will one day fully explain Rayleigh scattering, but only once The Ontarion pays for the 10-year education required to truly examine the phenomenon.
It’s important to recognize that it is physically impossible for the moon or Earth to ever truly cover the sun. That would imply that the Earth and moon are of a similar size; more importantly, it would imply that the moon and the Earth are of a similar size as the sun.
For scale, the Earth’s mass is 5.97 x 10^24 kg, the moon’s mass is 7.35 x 10^22 kg, and the sun’s mass is 1.99 x 10^30 kg. The sun is approximately 333,000 times larger than the Earth, while the sun is approximately 27 million times larger than the moon.
Why is an Eclipse important?
Our ancestors believed that eclipses were signs of impending doom—that civilizations rose and fell on the whims of celestial gods. For ancient humans, eclipses were important because they were apocryphal signs of times to come.
For modern humans, however, eclipses are not necessarily signs of the whims of the heavens, so much as they are signs that the heavens are fascinating. Interestingly enough, there are few reasons that eclipses are important, other than the fact that they are pretty cool.
Humans study science for a number of reasons—gaining knowledge for knowledge’s sake is noble, we are currently in the midst of a scientific revolution, it’s easy to find a job in a scientific or technological field.
Sometimes, knowing something isn’t necessary for nobility, or wealth, or position. Sometimes, knowing something is worthwhile simply because that something is interesting. Adding to the collective compendium of human knowledge is sometimes reason enough to learn.
What is the future of Eclipses?
There is not a single human being that has ever witnessed an eclipse on a planet other than Earth. As we look to the next generation of human existence, our species opens itself up to the possibility that we will witness a solar eclipse on Mars. Thanks to the Curiosity rover, we know what such an event looks like. One day, however, a real human will directly observe a Martian solar eclipse. As always, I’m excited for the truly absurd possibilities.
For those who are curious, the next total solar eclipse will occur on Aug. 21, 2017, and will be visible from Canada and the mainland U.S. The next total lunar eclipse will occur on Jan. 31, 2018 and will be visible from parts of the Pacific Ocean.