The point that occurs when the earth is furthest away from the sun. Auxin: a plant hormone, also called IAA, responsible for cell elongation, fruit development, and formation of adventitious roots. Carotene: yellow-orange colored, fat-soluble plant pigments found in chloroplasts and chromoplasts that aid in absorption of light for photosynthesis. Chlorophyll: a group of green colored pigments a and b that are the primary pigments involved in the absorption of light for photosynthesis. Compound leaf: a leaf, made of numerous leaflets, that is connected to the stem through a petiole.
The point on the annual orbit of a body (about the sun) that is farthest from the sun; at present, the earth reaches this point (152 million kilometer from the sun) on about 5 July. Opposite of perihelion.
The point on the earth's orbit that is farthest from the sun. Although the position is part of a 21,000 year cycle, currently it occurs around July, when the earth is about 3 million miles farther from the sun than at perihelion. This term can be applied to any other celestial body in orbit around the sun. It is the opposite of perihelion.
The point on the orbit of the earth (or any other body in orbit about the sun) that is farthest from the sun; the opposite of perihelion. At present, aphelion occurs about July 1, when the earth is about three million miles farther from the sun than at perihelion, but the seasons in which aphelion and perihelion fall undergo a cyclic variation with a period of twenty-one thousand years. The date of aphelion passage is advancing slowly (toward dates later in the calendar year) at a rate of about one-half hour each year. This is a consequence of the eastward rotation of the line of apsides at a rate of about 11 sec of arc per year and the precession of the equinoxes of about 50 sec of arc per year, for a total of 61.9 sec of arc per year. See apocenter, apogee.