#### What are the general characteristics of sun? Who discovered sun rotates? How much hot is sun? How far is sun? Information about sun.

SUN the central controlling body of the solar system. It is by far the largest member of the system, being 740 times more massive than its nine major planets together and 10 times wider than the largest planet, Jupiter.

The sun’s rays supply the earth with heat and light, contribute to the growth of plant life, evaporate water from the ocean and other bodies of water, play a role in the production of winds, and perform many other functions that are vital to the existence of life on earth.

As a star the sun is a typically yellow dwarf, inconspicuously loeated in a spiral arm near the outer edge of our Milky Way galaxy. In orbiting the center of the galaxy, it whirls toward the constellation Cygnus at a velocity of about 140 miles (220 km) per second. At the same time it speeds toward a point in the constellation Hercules at 12 miles (20 km) per second, in a transverse motion that is perpendicular to its galactic orbit.

## General Characteristics Of Sun

The sun is a glowing ball of gases about 865,000 miles (1,393,000 km) in diameter. In terms of relative mass, it consists of 69.5% hydrogen and 28% helium—an element first discovered on the sun. Carbon, nitrogen, and oxygen account for 2% of the mass, and magnesium, sulfur, silicon, and iron account for 0.5%. Other elements are present in the sun in trace amounts only.

Although the sun is gaseous throughout its entire structure, it appears to have a definite surface when viewed through a suitable filter. This is an illusion caused by the sun’s great distance from the earth, which averages about 92,960,000 miles (149,660,000 km) from the center of the sun to the center of the earth. The distance actually varies through the year because the earth’s orbit is slightly elliptical. Early in January, when the earth is elosest to the sun, the distance about 91,400,000 miles (147,150,000 km). Early in July, when the earth is farthest away, the distance is about 94,500,000 miles (152,140,000 km).

#### Galileo Galilei

As Galileo Galilei discovered in 1610, the sun rotates about an axis that is approximately aligned with the earth’s axis. The rotational movement is from east to west, as viewed from the earth, and the speed decreases from a period of nearly 27 days at the solar equator to a period of more than 30 days near the poles. That is, the gaseous sun rotates more rapidly at the equator than at the poles.

This rotating ball of gases has a mass of $\displaystyle 2,19x{{10}^{27}}$ tons (nearly $\displaystyle 2x{{10}^{30}}$ kg), which is 330,000 times the mass of the earth. Its average density is 88 pounds per cubic foot (1.41 grams per cu cm), which is 1.41 times the density of water but only a little more than 0.25 times the average density of the earth. However, the sun’s density inereases greatly toward the interior. The gas pressure at the apparent surface is only 1/10 that of the earth’s standard atmospheric pressure at sea level, and its density is only about 1/3500 that of terrestrial air at sea level, but at the center of the sun the gases are highly compressed by the great mass of material above them. The gas density there is nearly 100 times the density of water, or nearly 9 times the density of lead, and the pressure is 200 billion atmospheres.

#### Temperature

Temperature also inercases toward the interior, from about 10,000° F (6,000° C) at the apparent surface to more than 18,000,000° F (10,-000,000° C) at the center. Above the apparent surface the temperature first decreases to about 7,200° F (4,000° C) and then inereases rapidly to more than 1,800,000° F (1,000,000° C) in the outer atmosphere of the sun.

The gravitational pull at the surface of the sun is 28 times as strong as the gravitational pull at the earth’s surface. So strong is the sun’s gravity that it exceeds the earth’s gravitational pull for any object that is more than 160,000 miles (nearly 258,000 km) from the earth. Thus the moon experiences a stronger gravitational pull from the sun than from the earth.

mavi

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