Isaac Newton’s universal law of gravitation is an expansion of the planetary motion ideas developed by Johannes Kepler. One derivative of Newton’s universal law gives us a useful formula to find tidal forces on Earth caused by either the Sun or Moon. The tidal force depends on the mass m of the Sun or Moon, the radius r of Earth, and the cube of the distance d between Earth and either the Sun or Moon. (The G in the equation is known as the gravitational constant, and it doesn’t change.) Based on the equation and your knowledge of the Sun-Earth-Moon system, which celestial body (the Sun or the Moon) has a greater influence on Earth’s tides? Justify your answer.

interphase

the period of cell growth when the cell synthesizes new molecules and organelles. the cell is not dividing and it constitutes the majority of the time spent in the cell cycle

prophase

changes occur in the nucleus and cytoplasm. the chromatin condenses to form structures (sister chromatids) visible with a light microscope and the mitotic spindle begins to form, but the nucleus is still in tact

prometaphase

the nuclear envelope fragments and the spindle microtubules attach to the kinetochores of the sister chromatids

metaphase

all the cell's duplicated chromosomes are lined up at an imaginary plane equidistant between the poles of the mitotic spindle

anaphase

begins when sister chromatids separate from each other and ending when a complete set of daughter chromosomes arrives at each of the two poles of the cell

telophase

the daughter nuclei form at the two poles of a cell

cytokinesis

the division of a cytoplasm to form two separate daughter cells. usually occurs during telophase during mitosis. this and mitosis make up to mitotic (m) phase of the cell cycle