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| Rotation | A rotation is a circular movement of an object around a center of rotation. A three-dimensional object can always be rotated around an infinite number of imaginary lines called rotation axes. If the axis passes through the body's center of mass, the body is said to rotate upon itself, or spin. |
| Orbit | the curved path of a celestial object or spacecraft around a star, planet, or moon, especially a periodic elliptical revolution. |
| Day | a period of twenty-four hours as a unit of time, reckoned from one midnight to the next, corresponding to a rotation of the earth on its axis. |
| Equinox | An equinox is commonly regarded as the instant of time when the plane (extended indefinitely in all directions) of Earth's equator passes through the center of the Sun.[3][4] This occurs twice each year, around 20 March and 23 September. In other words, it is the moment at which the center of the visible Sun is directly above the equator. |
| Solstice | A solstice is an event occurring when the Sun appears to reach its most northerly or southerly excursion relative to the celestial equator on the celestial sphere. Two solstices occur annually, around June 21 and December 21 |
| Phases | each of the aspects of the moon or a planet, according to the amount of its illumination, especially the new moon, the first quarter, the full moon, and the last quarter. |
| Eclipse | An eclipse is an astronomical event that occurs when an astronomical object or spacecraft is temporarily obscured, by passing into the shadow of another body or by having another body pass between it and the viewer. This alignment of three celestial objects is known as a syzygy. |
| Tide | the alternate rising and falling of the sea, usually twice in each lunar day at a particular place, due to the attraction of the moon and sun. |
| Tide Rising | For the most part, the rise and fall of the tides is caused by the gravitational influence of the Moon. The Moon's gravity pulls the ocean surface upward, creating a bulge in the water -- high tide. Locations on Earth perpendicular to the Earth-Moon line experience low tide. |
| Spring Tide | Spring tides occur when the Moon is either new or full, and the Sun, the Moon, and the Earth are aligned. When this is the case, their collective gravitational pull on the Earth's water is strengthened. |
| Neap Tide | a tide just after the first or third quarters of the moon when there is least difference between high and low water. |
