What is an ocean tide?
An ocean tide is the cyclic rise and fall of Earth's ocean levels, primarily caused by the gravitational forces exerted by the Moon and the Sun, combined with the rotation of the Earth.
What is a tidal bulge?
A tidal bulge is a vast elongation of Earth’s ocean water caused by the gravitational interplay between the Earth and the Moon. The Moon’s gravity pulls ocean water toward it, creating a primary bulge on the side of Earth closest to the Moon. Simultaneously, a secondary bulge forms on the exact opposite side of the planet, where the Moon's gravitational pull is weakest, causing inertia to fling the water outward.
What is gravity?
Gravity is the invisible, fundamental force of attraction that exists between all matter in the universe. On Earth, gravity is what keeps our feet on the ground, holds the atmosphere in place, and causes dropped objects to fall. On a cosmic scale, it governs the motion of planets, keeping Earth in orbit around the Sun.
What is the relationship between mass and gravity?
The relationship between mass and gravity is directly proportional: as the mass of an object increases, its gravitational pull becomes stronger. Every object with mass exerts gravity, but the effect is only noticeable with massive bodies like planets. For example, because Earth has significantly more mass than the Moon, its gravitational pull is about six times stronger. This fundamental link dictates how planets hold onto their moons and how stars keep solar systems together.
What is the relationship between distance and gravity?
The relationship between distance and gravity is inversely proportional and follows the inverse-square law: as the distance between two objects increases, the gravitational force between them rapidly decreases. Specifically, if you double the distance between two objects, their gravitational attraction drops to one-quarter of its original strength. This means that while gravity technically reaches infinitely across space, its power fades drastically over long distances, allowing local objects—like our Moon—to dominate Earth's tides.
What is inertia?
Inertia is a property of matter that describes an object's resistance to any change in its state of motion. Governed by Newton's first law, an object at rest will stay at rest, and an object in motion will continue moving at a constant speed in a straight line, unless acted upon by an outside force. Inertia depends entirely on mass; the more mass an object has, the harder it is to move or stop.
What is a Spring tide?
A spring tide occurs when the gravitational pulls of the Sun and the Moon align to reinforce each other, creating the greatest tidal range. This phenomenon happens twice a month—during the full moon and new moon phases—when the Earth, Moon, and Sun form a straight line in space. The combined gravitational forces pull the oceans in the same direction, resulting in exceptionally high, high tides and unusually low, low tides.
What is a Neap tide?
A neap tide occurs when the gravitational forces of the Sun and the Moon pull at right angles to each other relative to Earth. This alignment happens twice a month during the first and third quarter moon phases. Because the Sun's gravity partially cancels out the Moon's pull, the tidal range is minimized. The result is a period of moderate tides, featuring unusually low high tides and higher-than-average low tides.
What are perigean tides?
Perigean Tides happen every single month when the Moon reaches perigee—the point in its elliptical orbit closest to Earth. The closer Moon exerts more gravity, resulting in slightly higher high tides than normal.
What are proxigean tides?
A proxigean tide is an exceptionally high spring tide that occurs when the Moon is at its closest monthly approach to Earth (perigee) while simultaneously aligning in a new or full moon phase. This rare, precise astronomical coincidence maximizes the gravitational pull on Earth's oceans. The resulting tidal forces produce dramatic, unusually high water levels and severe low tides, which can trigger coastal flooding if combined with strong offshore winds or storms
What are apogean tides?
An apogean tide occurs when the Moon reaches apogee, its farthest point from Earth in its elliptical orbit. Because gravitational force decreases with distance, the Moon's pull on Earth's oceans is at its weakest during this time. As a result, apogean tides feature a reduced tidal range, characterized by lower-than-normal high tides and higher-than-normal low tides. This effect is the exact opposite of the enhanced perigean tides.
In this module you will investigate the gravitational mechanics of our planet-moon system. Your challenge is to create a working model that successfully demonstrates the causes of both daily tides and monthly tidal cycles.
