Tony Olszewski, age 11, of Newport News, Virginia, for his question:
Do they know what the sun is made of?
Scientists tell us that our starry sun is a super sized package of atomic elements and nuclear energies. So far the solar spectrum has revealed that its material ingredients include more than 70 of the ordinary chemical elements from which our world is made. However, most of our cool planet's materials are frozen solid. The materials of the gaseous sun are separate particles. And most of its atoms, its pairs of atoms and molecules are ions, stripped of their electrons.
Though most of the earth's basic elements have been identified in the sun, they exist there in vastly different proportions. For example, the earth's most abundant ingredient is oxygen, which is quite scarce in the sun. About 98.5 percent of the earth's solid crust is built from oxygen and silicon, plus six other basic elements. The sun contains only small amounts of these materials.
On the other hand, gaseous hydrogen and helium are rather scarce on our planet. The total mass of the sun equals 333,000 times more than all the material in our world and scientists estimate that about three fourths of this solar material is hydrogen gas. The sun's second most abundant ingredient is helium.
The sun's volume is estimated to be about 337,000 million million cubic miles. If it were hollow it could swallow one and a third million earth sized planets, and have room for dessert. And the whole thing is a continuous nuclear bonfire. Every second, our friendly neighborhood star converts 657 million tons of its hydrogen fuel into 653 million tons of helium. The missing four million tons of, matter in this equation is converted into nuclear energy, most of which is radiated out into space. The seething temperatures of the solar furnace also make and remake other atoms. Hence, the 70 or so other ingredients may be there today gone tomorrow.
The ingredients in the sun are identified by the lines they etch on the rainbow spectrum. One useful instrument in this work is the spectrograph, a system of glass prisms that separate and photograph the sun's light. When any substance becomes a burning gas, it creates its own unique lines on certain ribbons of the rainbow spectrum. All the sun's materials are incandescent gases and the solar spectrum is streaked with thousands of identifiable lines.
The solar spectrum reveals the signatures of the elements carbon and nitrogen, oxygen and iron. The telltale lines also identify magnesium and nickel, aluminum and nickel, magnesium, calcium and sodium. Perhaps traces of all the earth's common elements also may be present.
It is important to remember that the bulk of the sun's material is hydrogen and helium. Atoms of the other 70 or so identified elements may be remodeled in the nuclear furnace. And as the sun grows older, it is thought that larger amounts of its original hydrogen will form quantities of titanium and various other metals.