How Did We Get Such a Good Understanding of Ocean Tides?
People have been observing the tides for a long time. After all, it is a natural phenomenon with a material impact on human societies, with an excellent example being how Julius Caesar lost a number of his ships on his British expedition because he was a native of the Mediterranean who was unused to British tides as well as British weather. As a result, it should come as no surprise to learn that our ancient predecessors offered up some rather remarkable deductions based on their observations.
For example, Pytheas of Massalia was a Greek explorer who visited Great Britain, the North Sea, and the Baltic Sea. As a result, his experiences enabled him to make a connection between the tides and the phases of the moon, which was particularly impressive because he is believed to have lived from around 350 BC to around 285 BC. Likewise, a number of people from a number of cultures made further contributions, with examples ranging from Seleucus of Seleucia who believed that the tides were caused by the moon to the Venerable Bede who noticed that the rising of the tides on one British coast coincided with the falling of the tides on the other side.
Later scholars voiced their opinions on the matter as well, though in some cases, their opinions were by no means better than that of their predecessors. For example, Galileo thought that the tides were caused by the motion of the Earth as it moved around the Sun, which was rather inaccurate to say the least. In contrast, Johannes Kepler concluded that the moon was responsible for causing the tides, but his speculation accounted for the existence of no more than a single tide on a daily basis. It wasn't until Issac Newton that the tides were explained as the result of the gravitational attraction of astronomical objects. However, while Newton was the one who came up with the explanation, there are numerous individuals who emerged as winners in his wake by furthering our understanding of the phenomenon through various ways.
What Causes Ocean Tides?
Considering what has been written, it shouldn't take the kind of luck needed to win at Yukon Gold for interested individuals to become winners by figuring out that the tides are caused by the gravitation attraction between the Earth and the moon.
In short, the Earth's gravity attracts the moon, much as how the moon's gravity attracts the Earth. However, since the Earth's gravity is much stronger than the moon's gravity, the center of their is situated much closer to the Earth than to the moon. To be exact, it is situated about 75 percent of the distance between the center of the Earth and the surface of the Earth, which is why the Earth and the moon move as they do.
The influence of the Earth's gravity and the moon's gravity causes both astronomical objects to become more elongated. However, this influence isn't that noticeable when it is exerted upon the land. In contrast, water is much more fluid, which in turn, means that the effects of this influence become much more obvious on water. The water on the surface of the Earth facing the moon bulges towards the moon, thus resulting in what we call high tide. However, this explains one high tide but not the other, which is why it is important to point out the elongating effect of gravitational attraction. Simply put, since the Earth is elongated by the moon's gravity, it stands to reason that the other side of the Earth would bulge outwards as well.
Speaking of which, it is worth mentioning that people don't need the kind of luck necessary to become winners at Yukon Gold to figure out that the sun has an effect on the tides as well. However, while the sun's gravity is much more powerful than the moon's gravity, it offers a smaller effect on the tides because it has a smaller effect on the gravity field over the Earth. With that said, there are times when circumstances line up so as to offer interested individuals a chance to see the effects of solar tides without needing them to win at Yukon Gold or something similar. After all, spring tides are when lunar tides are reinforced by solar tides, whereas neap tides are when lunar tides are countered by solar tides.