Thank our lucky stars for Earth's protective magnetosphere
By Amanda Jermyn

We can thank our lucky stars, or rather the laws of the universe that govern them, for the magnetic field that surrounds the Earth. Without it we would not be here.

So what is this magnetic field, and how does it protect us? The Earth’s center is comprised of a solid inner core surrounded by a liquid outer core made of molten iron. As the planet rotates, movement in the outer core generates electric currents that give rise to Earth’s magnetic field. In other words, the earth acts like a giant bar magnet, with force fields that extend from its core, reaching about 36,000 miles into space, flowing between earth’s magnetic south and north poles. It is this Earth-encompassing magnetic field, known as the magnetosphere, that protects us from damaging cosmic rays, the charged particles that bombard the Earth’s atmosphere from outer space.

Though space is rife with such particles, the solar wind, a stream of high energy particles emanating from the sun, is the main source of those targeting Earth. The intense heat of the sun causes a flow of free electrons and protons too hot to form atoms to radiate in all directions, including towards Earth. Our planet’s magnetosphere deflects most of these charged particles so that they flow around the Earth, rather than towards it, though some do flow towards the Earth’s magnetic poles where the lines of magnetic force are greatest. Collisions between these charged particles and nitrogen and oxygen atoms in Earth’s upper atmosphere lead to the release of energy in the form of light, resulting in vivid aurora displays, usually occurring close to the poles. The recent solar flare on January 23rd produced dramatic auroras around the North Pole, and led to air traffic being diverted from this region because the intense stream of charged particles interferes with radio communication. However, under normal circumstances, most cosmic rays are deflected away from Earth by its magnetic field.

In the absence of such protection these charged particles would erode the ozone layer which protects Earth from ultraviolet rays that can cause damage to living organisms, including cancer in humans and animals. Not all planets have the right conditions to generate a protective magnetic field. Other planets within our solar system that have a magnetosphere are Mercury, Jupiter, Saturn, Uranus and Neptune. Mars may have a very weak one, but Venus has none. Those without a magnetosphere would be hostile to life. They would be unable to maintain protection from radiation from space, and their surfaces would be bombarded by harmful cosmic rays. Earth’s magnetic field is the strongest among the rocky planets, strong enough to protect us from lethal cosmic rays, and a reminder of life’s fragility within the universe.

Join the Springfield STARS Club on Tuesday, February 28th at 7:30pm at the Springfield Science Museum for a talk by amateur astronomer Paul Cardone on the topic, “An Astronomer’s Journey into the Desert,” about his adventures setting up telescopes, observing the night sky, and astrophotography at Casita de Gila in New Mexico. Paul works in Information Technology at MassMutual Life Insurance Company and is active in astronomy outreach locally. He gives astronomy talks at schools, builds telescopes, and organizes star parties at schools where students can look through telescopes and learn about the night sky. Refreshments will be served, and the public is welcome free of charge.

Also, on Friday, March 2nd at 7:30pm the STARS Club and Springfield Science Museum will host “Stars over Springfield,” an astronomy adventure for the whole family. Ed Faits, president of the Arunah Hill Natural Science Center, will present “One Small Step,” a look back at the Apollo moon landings. Participants will have an opportunity to examine authentic moon rocks and lunar soil samples collected by Apollo astronauts and on loan from NASA, courtesy of Skip Price, Professor of Geology and Astronomy at Greenfield Community College. Observing through the Science Museum’s rooftop telescope will follow, weather permitting. A fee of $3 for adults and $2 for children under 18 will be charged.