About our sun
93 million miles from where you are sitting right now, at the center of our solar system is the biggest ball of gas you've ever seen. You see it every day, and without it you wouldn't exist.
I'm talking about the Sun of course. And even as you read this it's caught in a struggle between the force of gravity trying to squeeze it out of existence and the atomic explosion at its heart trying to blow it into pieces.
ANATOMY OF THE SUN:
The Sun is like an onion, filled with gaseous layers.
Corona: The outer most layer and the visible part during an eclipse.
Chromosphere: The "middle layer."
Photosphere: The "surface" of the Sun.
Core: This is the furnace that powers the Sun.
SIZE AND TEMPERATURE:
The Sun is big. Really big. It's the biggest thing in our solar system, and accounts for over 99% of the entire mass of the solar system. Here are the details:
DIAMETER: The diameter of the Sun is 870,000 miles (109 times larger than the Earth's). It would take more than 100 Earths laid side by side to span the width of the Sun. VOLUME: It's big enough to hold over 1 million Earths. If the Sun were a basketball, then the Earth would only be the size of the head of a pin. The Sun is also extremely hot. Even at its coolest point it is still 2.1 million degrees F.
CORE TEMPERATURE: 18 Million degrees F.
SURFACE TEMPERATURE: 10,000 degrees F.
It takes 8 minutes for sunlight to travel 93 million miles from the surface of the Sun to reach us here on Earth. Along with the visible light, the Sun also emits harmful ultraviolet (UV) radiation as well as radio waves and x-rays. UV radiation, which can damage your skin and eyes, is the source of sunburns, suntans and skin cancer.
While the Sun's light can be harmful to humans, it's also necessary for life. Without the Sun, the Earth would be a frozen rock drifting dead in space. The Sun provides the light, heat and energy needed for plants to grow, and animals to live.
Solar flares are the result of disturbances in the Sun's electromagnetic field. These disturbances cause large amounts of gas and particles to be ejected into space.
These particles travel out towards the planets at a million miles per hour. When these particles reach the Earth's outer atmosphere, it often impacts satellites, which disrupts radio and cell phone communication.
Solar flares also cause the northern and southern lights. When the ejected particles make contact with the Earth's outer atmosphere, they cause the gas in the atmosphere to release light. This light appears in many different colors and is called the "aurora." The aurora in the northern hemisphere is called the Aurora Borealis, but is more frequently known as "northern lights." Similarly, in the southern hemisphere they are known as "southern lights" or Aurora Australis.
Sunspots are areas of the surface that are cooler than the areas around them (roughly 2780 degrees F difference). Because they are cooler and emit less radiation, they appear darker than the hotter gas around them.
The number of sunspots is closely related to the Sun's magnetic field activity. The more active the field, the higher the number of sunspots, and the more flares. Typically, this is an 11-year cycle from one period of maximum activity to the next maximum.
LIFE AND DEATH:
Our Sun is a middle-aged star and it turns hydrogen into helium through nuclear fusion in its core. Our Sun is about 4.5 billion years old, and is expected to be around for another 5 billion. The Sun is mostly hydrogen (70%) and helium (28%), which means it has plenty of fuel to burn.
In 5 or 6 billion years our Sun will run out of hydrogen. Gravity will squeeze it until it is small enough and hot enough for its helium core to ignite. This will cause the Sun to expand rapidly and engulf the inner planets. Mercury, Venus, Earth and Mars will be vaporized as the Sun swells to a Red Giant.
Eventually, even the helium will run out and the Sun will shrink again to become what astronomers call a White Dwarf. The Sun will remain a White Dwarf until the end of time.