What is the Sun? Why does the Sun shine? Is it just a ball of burning gas? To us on Earth, it is much more than that; it is an anchor and protector, a heater and source of constant energy. It is dangerous and, at the same time, life providing. It is the center of our solar system. It may prove to be the instrument of doom to our Earth.
The Sun is huge. It is the most dominant object in our solar system. About 99.8% of all the mass of our solar system is in the Sun. If one adds up all the planets, moons, asteroids, comets and dust in our system, the total would equal little more than 1% of the Sun. It is not a huge star. After all, the largest stars can be as much as 1,000 times larger than ours. But the Sun is more massive and brighter than 95% of the stars in our galaxy.
The Sun sends out lots of energy. But what kind energy does it emit? Most of it is light (photons) and infrared rays. The infrared rays are not only seen but are also felt. We call it heat. These are forms of electromagnetic radiation.
The Sun is very dangerous. Not only does it send out light, heat and radio waves, but dangerous ultraviolet rays, gamma and X rays emitted from it would kill us if it were not for the protection of our atmosphere.
The Sun is hot, so hot that it can burn our skin from 93,000,000 miles away! It is a blazing nuclear furnace. Not only is it hot, but it shoots out flames for more than two hundred thousand miles before pulling back to the Sun’s fiery surface. The Sun produces light. It creates photons that speed out beyond our solar system, even beyond our galaxy. Some of these photons have now traveled nearly 5 billion years, moving at 186,000 miles per second. Someone far out in the Universe could be just now receiving this light message. It is the story of the beginning of our solar system and of the star that rules it.
It pulls in debris that could otherwise hit circling objects. Our star keeps us from wandering away and smashing into other objects.
The Sun spins, just as other large bodies in space. It takes the star’s equator about 25 days to rotate. The upper and lower regions take about 28 earth days for a complete turn. Why? Because the object is made of gas is not a solid.
The Sun is violent. It does not have a stable surface area. Portions as big as Texas come to the surface, then cool and disappear in less than 5 minutes. Solar storms and explosions push out flames and winds that contain cosmic particles, known as solar cosmic rays that have effects for hundreds of millions of miles. The rays made up of mostly ejected protons, have some heavier nuclei and electrons. These rays can cause great harm to space travelers, probes and satellites. They cannot enter the earth’s protective atmosphere but can create a magnetic storm when colliding with the upper atmosphere. This may lead to interference or disruptions in our electrical power grids and communications.
Some more facts:
The Sun puts out a tremendous amount of power. The amount of energy the Earth alone receives is equal to 126 watts per square foot per second! That means that one weeks’ worth of solar energy landing on Earth is equal to us using all our natural reserves of gas, oil, and coal on the entire planet during the same amount of time. The difference is that the Sun will be able to do that every week for billions of years.
The average distance between the Sun and Earth is 93,000,000 miles (1AU).
It takes about 8.3 minutes for the Sunborn light to reach us at this distance.
The diameter of the Sun is 864,000 miles.
It has a surface gravity 28 times stronger than that of Earth.
More than 70 elements (atoms) can be found in the Sun. The main ingredients are hydrogen (72%) and helium (26%); the core is thought to be 38% helium.
The Sun orbits the center of our galaxy every 250 million earth years.
Our Sun is known as a “population one”, star. There are three generations of stars, “population ones” being the youngest generation. They have the highest amounts of helium and heavier elements inside them.
Dissecting Our Sun
The corona is the highest layer of the Sun’s atmosphere. It reaches out several million miles into space. It is very hot and is seen as an uneven halo around the Sun during total solar eclipses.
Next is an area that is called the transition region. It is a hot area that cannot be detected with observations during a solar eclipse. It emits light in the ultraviolet bands. It receives most of its energy from the corona.
The chromosphere is a thin, transparent layer that extends out 6,000 miles from the photosphere. One can only see it from Earth when there is a total eclipse of the Sun.
A solar eclipse means the Moon is between the Earth and the Sun. The Moon will block out all but the very outer edges of the Sun from our sight.
The photosphere is the lowest level of the atmosphere. It is about 300 miles thick and is the visible surface of the Sun. It is about 10,000 degrees Fahrenheit. The Sun has a grainy look on its photosphere. Its appearance resembles a leathery skin.
The bright areas called granules have been seen as big as 625 miles wide. They are the result of rising currents from the convection zone.
The darker surrounding areas are about 300 degrees cooler. Those dark areas are from descending gases and typically last five minutes.
The granules can be part of greater super granules that can be up to 19,000 miles in diameter. These are composed of a number of granules banding together. Super granules can last for several hours. that of water.
Nuclear reactions take place in the core, or center of the Sun, as hydrogen is converted in to helium. This is an area where the density of the star is 15 times that of lead. Here, the gas pressures are 2 million times that of the earth’s atmosphere. Fusion, (when two atomic nuclei merge.) takes place here. Nuclear matter is turned into energy. Photons are created. These are the particles that, when grouped together in a moving stream, we call light. Some are absorbed. Others escape.
The radiation zone surrounds the core. It is named the radiation zone because the energy that passes through it is mainly radiation in nature. This makes up 48 percent of the Sun’s mass. It may take a photon over 1,000,000 years to pass through this zone.
Spiricules are jets of gas that reach out as far as 6,000 miles into space and are up to 600 miles wide. Found in the chromosphere, they last anywhere from 5 to 15 minutes.
Did you know?
It is estimated that it takes up to 1 million years for a photon to escape to the Sun’s radiation zone and reach the surface. It then takes less than 9 minutes to get to Earth. That means the light you see from the Sun is about 1 million years and 9 minutes old!
Sunspots are darker areas found on the photosphere, usually found in groups of two or more, these spots can last from a few hours to a few months. They can best be seen during sunrise or sunset. Do not look for them without expert help and proper instruments! The first observations of sunspots were recorded in China around 800 BC. Galileo was the first to observe them with a telescope.
Sometimes there are no sunspots on the surface. At other times people have recorded as many as 250 of them. There seems to be a pattern of activity called the sunspot cycle. It is about 11 years from the start to end. When it is at its higher level of activity it is called the sunspot maximum.
The Sun, like earth, has a magnetic field. If taken as a whole, it is only twice as strong as the earth’s field. But, in certain areas, there are concentrations of magnetism that can be as strong as 3,000 times that of Earth. These areas are where we find sunspots. Sunspots act like super magnets. This magnetic field shows up before the spot can be seen and it lingers for a while after the spot is gone. There is a background magnetic field around the Sun. The magnetic axis is tilted at 15 degrees from true north and south.
This field is filled with energized particles created by the Sun’s rotation and gas convections. They cause outbursts of radiation and other materials.
Every 11 or so years the magnetic poles on the Sun reverse. This happens just after the sunspot activity reaches its height, thus creating a cycle of solar activity of 22 years.
Solar flares are tremendous explosions of light, radiation and particles. They can reach a height up to 200,000 miles and can produce more energy than our world can create in 100,000 years. Flares can send out 20 billion tons of matter into space during an eruption. These flares have a life span of only a few minutes. They are mostly seen when there is an abundance of sunspot activity.
Prominences are arched ionized gases that occur on the limb of the Sun. Magnetic fields and sunspots supply the energy for them. Solar winds are streams of electrically charged particles flowing out from the Sun. Unlike our wind, it is very thin, hot and extremely fast, an average speed is close to 1 million miles per hour. The solar wind takes about 4 days to travel from the Sun to the Earth. Sunspot activities affect these winds. When there are sunspots, the winds are the strongest. The winds end up somewhere beyond Neptune.
The Sun will not stay forever the same as it is now. Previously, it was mentioned that the Sun will grow dimmer. As time goes on the Sun will start running short of its main fuel, hydrogen. On the other hand, it has been developing a new fuel that will eventually power the star; helium. The Sun will someday switch over completely burning helium and will turn red in color. The temperature will drop, and the star will dramatically expand. It will then be a red giant, burning helium. The closest three planets that presently are orbiting the Sun will be actually end up within our sun! The Sun will once again change. This time it will end up as a white dwarf, burning the last of its hydrogen. During this phase it will burn off the last of its hydrogen. Eventually, the sunlight will flicker and dim. Finally it will end up being a black, burned out, cinder ball in space.
The Sun is about half way through its life cycle. It has a little less than 5 billion years of life to go. Right now it is nearly as bright as it will ever be. It is brighter now than 2 billion years ago and it is brighter than it will be 2 billion years in the future.