The Star Has Turned On

The Star Has Turned On

Stars and their accompanying planets are born in the gravitational collapse of a cloud of interstellar gas and dust. The collision of the gas molecules in the interior of the cloud heats it, eventually to the point where hydrogen begins to fuse into helium: four hydrogen nuclei combine to form a helium nucleus, with an attendant release of a gamma-ray photon. Suffering alternate absorption and emission by the overlying matter, gradually working its way toward the surface of the star, losing energy at every step, the photon’s epic journey takes a million years until, as visible light, it reaches the surface and is radiated to space.

The star has turned on

The gravitational collapse of the prestellar cloud has been halted. The weight of the outer layers of the stars is now supported by the high temperatures and pressures generated in the interior nuclear reactions. The Sun, our nearest star, has been in such a stable situation for the past five billion years.

Thermonuclear reaction like those in a hydrogen bomb are powering the Sun in a contained and continuous explosion, converting some four hundred million tons (4x 10(14) grams) of hydrogen into helium every second. When we look up at night and view the stars, everything we see is shining because of distant nuclear fusion.

It is not impossible that to some infinitely superior being the whole universe may be as one plain, the distance between planet and planet being only as the pores in a grain of sand, and the spaces between system and system no greater than the intervals between one grain and the grain adjacent (Samuel Taylor Colbridge, Omniania). Image : Bright Colors by © Megan Jorgensen

We have examined our Sun in various wave-lengths from radio waves to ordinary visible light to X-rays, all of which arise only from its outermost layers. It is not exactly a red-hot stone, an Anaxagoras thought, but rather a great ball of hydrogen and helium gas, glowing because of its high temperatures, in the same way the poker glows when it is brought to read heat.

Anaxagoras was at least partly right: Violent solar storms produce brilliant flares that disrupt radio communications on Earth; and immense arching plumes of hot gas, guided by the Sun’s magnetic field, the solar prominences which dwarf the Earth. The sunspots, sometimes visible to the naked eye at sunset, are cooler regions of enhanced magnetic field strength. All this incessant, roiling, turbulent activity is in the comparatively cool visible surface. We see only the temperatures of about 6,000 degrees. But the hidden interior of the Sun where sunlight is being generated, is at 40 million degrees.