Chloe White

1. Secrets of the Sun Chloe White

2. What is the Sun? • The Sun is a Star, similar to other stars that appear in the sky but because it is so close to Earth and also because there is so much heat coming from it and it is so bright it always appears to be much bigger than it actually is. • There are many stars that appear in the sky at night and in fact a lot of these stars are much bigger than the Sun but the Sun is the centre of our Solar System and all of the planets in our Solar System, including Earth, orbit around the Sun. • The Sun is an essential source of heat and light for the planets in our Solar System.

3. The Sun - What is it made of ? • The Sun is made up of hot gases – a massive glowing sphere of hot gas. It contains many of the same materials we find here on the Earth. These materials, called elements include Hydrogen, Helium, Calcium, Sodium, Magnesium, and Iron. Most of the Sun is made up of Hydrogen - about 70%and Helium - about 28%. Carbon, Nitrogen and Oxygen account for about 1.5% and the remaining elements make up 0.5%.

4. How hot is the Sun? • A process called fusion heats the Sun. Fusion happens in the core of the Sun, which is very hot . In fact, the core's average temperature is around 27,000,000 degrees Fahrenheit. The surface of the Sun is cool compared with the core, only 10,000 degrees Fahrenheit. Fusion not only heats the Sun, but it makes the sunlight we see here on Earth. This sunlight travels the speed of light which is 186,282 miles per second or 299,792,458 meters per second. This means the light from the Sun takes 8.4 minutes to travel 93 million miles to Earth. If the world's fastest land animal were to travel that same distance, it would take a cheetah over 151 years to reach the Earth running about 70 mph nonstop!

5. How old is the Sun? • The Sun was actually formed from a nebula over 4 and a half billion years ago. A nebula is a cloud of dust and gas (often called "gust"). If enough of this dust and gas gather together, a star can form inside a nebula. The Sun is now halfway through its life span. So in another 5 billion years, the Sun might begin to change. The Sun will expand, becoming a red giant. The Sun will be so big that it will engulf Mercury, while Venus will probably orbit just outside of the Sun's surface. The Earth will be scorched at this point, leaving the planet unsuitable for life. Pluto, in fact, would be the only planet suitable for any life in the solar system.

6. How old is the Sun? This is the life cycle of the Sun. At the very end of its life cycle, the Sun is likely to blow off its outermost layers. It will then shrink to the size of the Earth, becoming a cooler white dwarf star.

7. How does the Sun produce energy? • When we say the Sun "burns", that's really not what we mean. The Sun produces energy the same way a hydrogen bomb does. Everything in the Universe that is solid, liquid or gas (like a rock, or a flower, or a glass of water) is made of tiny particles called atoms. There are different kinds of atoms. The lightest kind is called hydrogen, and it is the most common atom in the Universe. All the stars you can see when you look at them at night are almost completely made up of hydrogen.

8. How does the Sun produce energy? When Hydrogen is squeezed very hard , lots of the atoms will stick together, and change the way they are . This is called atomic fusion. The fused atoms form the next heavier type of atom, which is Helium (the same one that is used in balloons). When they do this, they give off a little bit of energy. It's not much but the Sun has lots of Hydrogen. In the core of the Sun the pressure is high enough (and it's hot enough too) to make Hydrogen turn into Helium in huge amounts. There is so much Hydrogen being converted to Helium (hundred of millions of tons every second!) that a huge amount of energy is released. This is what causes the Sun to shine. That energy works its way out from the core of the Sun to the surface and then shines down on the Earth and all the other planets.

9. Effects of the Sun on the Earth The Sun's rays (or rays of sunlight) are radiation that comes from the Sun. This radiation is important for life on Earth because it keeps our planet warm. However, too much exposure to the Sun's rays can be harmful to your skin. The sun can give people energy in a couple ways. When sunshine warms your body it is giving you some heat energy through radiation. The most important way the sun gives us energy is through the food we eat. Plants can convert the suns energy into food for itself, which we can eat. In fact, all the food we eat relies somehow on the sun.

10. Effects of the Sun on the Earth A solar eclipse occurs when the Moon comes between the Earth and the Sun, so the light from the Sun is blocked. A lunar eclipse happens when the Earth comes between the Moon and the Sun, so that when we look at the Moon we see the shadow of the Earth on the Moon. We have night and day because Earth is rotating and the Sun only shines on the side that is facing toward it. It might be simpler to think of a person standing a short distance from a lit lamp. If that person spins in place, one side of them is lit up, while the other side (the side away from the lamp) is dark. In this case, the side of the person toward the lamp will be in "daylight", and the side away from the lamp will be in "night".

11. Sunspots Sunspots are made up of two parts: a dark, circular central disk called the umbra, and a lighter outer area called the penumbra. The appearance of the area outside of the sunspot is the result of convection. The center of each granule is hot material rising from the sun's interior, while the edges are cooler material sinking downward. The sun has a magnetic field that is twisted around inside the sun as it spins. There are places on the sun where this magnetic field rises up from below the sun's surface and pokes through, creating sunspots. Sunspots are magnetic and often have a North and South pole like a magnet. They come and go over the surface of the sun and last from a few days to a few weeks.

12. How big is a Sunspot? The average sunspot is about the size of the entire planet Earth. However, sunspots come in a variety of sizes ranging from hundreds to tens of thousands of miles across (many times larger than Earth). Scientists measure the total of all of the sunspots seen on the sun every day to get a measure of how active the sun is. Sunspots are not permanent. They appear and disappear on the surface of the sun.

13. Who first discovered Sunspots • Who first noticed sunspots? It's hard to say, as the records left by many ancient peoples have been lost (or not kept in the first place). But as early as 28 B.C., astronomers in ancient China recorded systematic observations of the cycles of what looked like small, changing dark patches on the surface of the sun. And there are some early references to sunspots in the writings of Greek philosophers from the fourth century B.C. However, none of the early observers could explain what they were seeing. What could sunspots be?

14. Who first discovered Sunspots There is some debate over which European was first to discover sunspots. The credit is usually shared by Johann Goldsmid (known as Johannes Fabricius) of Holland, Galileo Galilei of Italy, Christopher Scheiner of Germany, and Thomas Herriot of England, all of whom claimed to have discerned sunspots sometime in 1611. All four men observed sunspots through telescopes, and made drawings of the changing shapes by hand, watching the spots traverse the visible surface of the sun. These drawings were the first steps toward understanding sunspots. Christopher Scheiner Johannes Fabricius Galileo Galilie of Italy

15. The Sunspot Cycle • In the last few decades, the forces behind sunspots are becoming better understood, but we've known for over a 150 years that sunspots appear in cycles. The average number of visible sunspots varies over time, increasing and decreasing on a regular cycle of between 9.5 to 11 years, on average about 10.8 years. An amateur astronomer, Heinrich Schwabe, was the first to note this cycle, in 1843. The part of the cycle with low sunspot activity is referred to as "solar minimum" while the portion of the cycle with high activity is known as "solar maximum.“ • By studying the sun's magnetic field, modern astronomers have discovered that the cycle covers twenty-two years, with an eleven-year cycle of sunspots above the equator followed by an equal cycle below the equator. It turns out that the magnetic fields primarily point from west to east in the Northern Hemisphere (of the sun), and from west to east in the Southern Hemisphere. In the next eleven-year cycle, the fields are reversed. So the cycle is really twenty-two years. • Sunspots most often appear in the low latitudes near the solar equator, and they almost never appear below 5 or above 40 degrees north and south latitude. As the sunspot cycle progresses, the visible sunspots move gradually towards the equator.

16. Pictures of Sunspots

17. What is a Solar Storm • Solar Storms are caused by superhot explosions of gas and charged particles from the sun’s surface. These are called Coronel Mass Ejections (or CMEs for short) and are similar to Solar Flares. • Solar storms can cause problems with radio transmittions from satellites orbiting the planet. • In 1997, a solar storm shut down an important Television satellite that provided television broadcasts. • They can also affect mobile phone transmittions.

18. Climate change ... is it linked to the Sun? For years there has been a debate going on about whether or not the sun was to blame for our recent climate change. But now the debate seems to be settled as a scientific report states that while sun activity has gone down during the past 20 years, the earth’s climate has become more out of the ordinary. Creating extreme cold in normally warm places, and vice versa. Next to that there has been extreme drought in places like Australia and excessive rainfall in places all over the world.

19. Climate change ... is it linked to the Sun? Long-term climate records are a key to understanding how Earth's climate changed in the past and how it may change in the future. Direct measurements of light energy emitted by the sun, taken by satellites and other modern scientific techniques, suggest variations in the sun's activity influence Earth's long-term climate. However, there were no measured climate records of this type until the relatively recent scientific past. According to http://news.bbc.co.uk/2/hi/uk_news/6290228.stm- A new scientific study concludes that changes in the Sun's output cannot be causing modern-day climate change.It shows that for the last 20 years, the Sun's output has declined, yet temperatures on Earth have risen.It also shows that modern temperatures are not determined by the Sun's effect on cosmic rays, as has been claimed.

20. Research www.wikipedia.com www.windows.ucar.edu/tour/link=/kids_space/qsun_eff.html http://news.bbc.co.uk/1/hi/uk/6290228.stm www.askjeeves.com