The Sun is of great importance to the Earth. It is a source of heat and light which allows life to exist on Earth. That was noticed a long time ago by the ancient peoples. That is why in ancient times the Sun was considered the most important deity. Without the Sun's energy, life as we know it, could not exist on our home planet. Can we imagine our life without the Sun's light and heat? What would happen?
Without the Sun's heat and light, the Earth would be a lifeless ball of ice-coated rock. Without the Sun's rays, all photosynthesis on Earth would stop. All plants and all animals, including humans, could not stay alive, because they rely on plants for food. In short, there would be no life.
In this lesson, we are going to learn about the SUN, and we will discuss:
The Sun is:
Stars are space objects that produce their own energy through the fusion reaction of gasses. The Sun produces energy by the fusion reaction of Hydrogen turning into Helium in its core. Fusion happens when lighter elements are forced together to become heavier elements. When this happens, a huge amount of energy is created. The Sun converts about 5 million tons of mass into energy every second. This energy heats the Sun, so, the Sun heats Earth and all the other planets.
The Sun is NOT:
The Sun consists of
The Sun has six layers. Three layers, the corona, chromosphere, and photosphere, comprise the sun's atmosphere or outer layer. The other three layers, convective zone, radiative zone, and core, comprise the inner layers, or the parts of the sun that are not seen.
Knowing that we get the heat from the Sun, and the Sun is so far from the Earth, it can be concluded that the Sun is very hot. But how much is it really hot?
The temperature at the surface of the Sun is about 10,000 Fahrenheit (5,600 Celsius). The temperature rises from the surface of the Sun inward towards the very hot center of the Sun where it reaches about 27,000,000 Fahrenheit (15,000,000 Celsius). The temperature of the Sun also rises from the surface outward into the Solar atmosphere. The uppermost layer of the solar atmosphere, called the corona, reaches temperatures of millions of degrees.
There are cooler parts on the Sun's surface called Sunspots. Sunspots are areas that appear dark on the surface of the Sun.
The Sun is the center of our solar system, and its gravity holds the solar system together. Everything in our solar system revolves around it – the planets, asteroids, comets, and tiny bits of space debris. The Sun is the only star in our solar system.
The Sun is much bigger than all other celestial bodies around it. The other surrounding celestial bodies due to the great attractive force of the Sun are forced to move along certain paths around. Its gravity holds the solar system together. Planets revolve around the sun in fixed orbits.
The Sun and the whole Solar System revolve around the center of our own galaxy - the Milky Way.
The sun rotates around its axis once in about 27 days. Since the Sun is a ball of gas/plasma, it does not have to rotate rigidly as the solid planets and moons do. In fact, the Sun's equatorial regions rotate faster (taking only about 24 days) than the polar regions (which rotate once in more than 30 days).
As the planets revolve around the Sun, the sun revolves around the center of the Milky Way galaxy. It takes about 225-250 million years to revolve once around the galaxy’s center. This length of time is called a cosmic year.
The Sun is at an average distance of about 150 million kilometers (93,000,000 miles ) 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.
The distance between Earth and the Sun changes during a year. At its closest, the Sun is 147.1 million km 9 (1.4 million miles) away from us. At its farthest, the Sun is 152.1 million km (94.5 million miles ) away.
Compared to Earth, the Sun is enormous! It contains 99.86% of all of the mass of the entire Solar System. The Sun is 864,400 miles (1,391,000 kilometers) across. This is about 109 times the diameter of Earth. The Sun weighs about 333,000 times as much as Earth. Earth is about the size of an average sunspot.
