Sky Watch: The sun

Closest star contains 99 percent of solar system mass

Published Jan 22, 2014 at 12:06AM

Now that Oregon is deeper into winter’s chilling grip, many readers may already be looking forward to sunnier months ahead. Let us consider the sun and its life-sustaining attributes. First, and primarily for younger readers, never, ever look at the sun even for split second without approved solar-viewing equipment.

Nearly everyone realizes how important the sun is to Earth and almost all life on our planet. Nevertheless, it may come as a revelation that the sun contains about 99 percent of all the mass in the solar system. Everything else — planets, moons, comets, asteroids and other detritus — contribute less than 1 percent. This gargantuan solar mass is necessary to generate sufficient heat through gravitational compaction to cause hydrogen to fuse into helium, the sun’s primary source of energy. From the standpoint of physics, the sun does not burn. It fuses lighter elements into heavier elements. This process converts mass into energy at a much higher rate than chemical burning.

With the exception of geothermal, nuclear and moon-generated tidal energy, virtually all other energy comes to Earth directly or indirectly from the sun. Energy from a wood fire can be considered stored energy from the sun. Wind power results from differential heating of Earth’s atmosphere and is also produced by the sun. Hydroelectric power is created when water vapor is lifted by solar heat and accumulates as rainwater in rivers and lakes that eventually spin turbines in hydroelectric plants. Gasoline, coal and natural gas are hydrocarbons that would not exist without energy from the sun.

An energetic type of wind, the solar wind, is created by a flow of charged particles from the sun streaming outward in all directions. Aurora borealis, occasionally visible from Bend, and Aurora australis, the northern and southern lights, are caused by these particles spiraling down into the Earth’s magnetic field, generating beautiful shimmering light shows. From time to time, huge ejections of materials called plasmas are emitted from the sun in the form of coronal mass ejections. When they impact Earth, communications blackouts and power grid damage may occur over widespread areas. Sensitive electronic components in satellites can be damaged or destroyed. With sufficient warning, some satellites may be turned to present protective shielding toward the particle onslaught. Voltages in electricity transmission lines can be adjusted to prevent damaging and costly power outages. For a comprehensive discussion of the sun, current solar imagery and solar weather, visit the Solar and Heliospheric Observatory website at www.nasa.gov/mission_pages/soho.

— Kent Fairfield is a volunteer with Pine Mountain Observatory and a lifelong amateur astronomer. He can be reached at kent.fairfield@gmail.com. Other PMO volunteers also contributed to this article.