Noun. 1. thyroxine-hormone produced by the thyroid glands to regulate metabolism by controlling the rate of oxidation in cells; thyroxine is 65% iodine. tetraiodothyronine, thyroxin, T. thyroid hormone-any of several closely related compounds that are produced by the thyroid gland and are active metabolically.hyroxine. n. 1. (Biochemistry) the principal hormone produced by the thyroid gland: it increases the metabolic rate of tissues and also controls growth, as in amphibian metamorphosis. It can be synthesized or extracted from the thyroid glands of animals and used to treat hypothyroidism.
The Sun is at an average distance of about 93,000,000 miles (150 million kilometers) away from Earth. It is so far away that light from the Sun, traveling at a speed of 186,000 miles (300,000 kilometers) per second, takes about 8 minutes to reach us.Like all of the other planets in our Solar System, Earth does not travel around the Sun in a perfect circle.his means that the distance between Earth and the Sun changes during a year. At its closest, the Sun is 91.4 million miles (147.1 million km) away from us. At its farthest, the Sun is 94.5 million miles (152.1 million km) away.
How far is Mercury away from the sun? Astronomers convert large distances such as these to astronomical units. An astronomical unit (AU) is 93 million miles, which is the average distance from the sun to Earth. In this regard, Mercury's average distance from the sun is 0.387 AU. To put this into perspective, Neptune's average distance from the sun is 30.1 AU. The closest Mercury comes to Earth during its orbit is 48 million miles.