At the end of the story about Noah and the great flood, a rainbow appears as a symbol of God’s promise that this will never happen again. But there is a better reminder of a force that protects us every day…the Aurora.
Observing the Northern Lights has been on my bucket list; but that took a tumble down the list when I discovered that they can only be observed at the earth’s poles (I knew that) in winter (didn’t know that).
So how are the Northern Lights a sign that we are being protected?
The story can be told by comparing Earth and Mars development. Earth and Mars were very similar when they formed over 4 billion years ago. Both had an atmosphere, chaotic activity, water and carbon, the key elements for life. Even more important, both had geothermal vents which many scientists believe is where life began.
Mars was once a blue planet with a vast sea that covered 1/5th of its surface. Large, freshwater lakes on Mars survived for hundreds of millions of years. It had a 2 ½ mile deep waterfall!
Yet today, Mars is a cold, red, dry, dusty planet and its neighbor, earth, is a blue planet teeming with life and water.
Approximately 3.7 billion years ago, the chance for life on Mars evaporated with its atmosphere.
Scientists believe the atmosphere was removed by solar winds.
Solar winds are streams of charged particles from the sun that can strip away the atmosphere. Unlike Mars, Earth is protected by a strong magnetic field that forms around it like a shield. Earth’s magnetic field invisibly surrounds our planet; but on some wintry days near the poles, we can see it in action—the aurora.
Our auroras are a visible spectacle of our magnetic field protecting us from the solar winds…all in a mysterious and beautiful display. Technically, the aurora is a result of disturbances in the magnetosphere caused by solar wind, but I like my description better.
So why does earth have this protection and Mars does not? (As it was explained to me) Planets’ magnetic fields are formed by the liquid iron in their cores. Earth’s size means that it has enough liquid iron to generate a formidable magnetic field. Mars, on the other hand, is a much smaller planet, so it generated a weaker magnetic field. The combination of Mars’s distance from the sun and its relatively small size destroyed its magnetic field, allowing solar winds to gradually rob Mars of its chance for life. Billions of years ago, it stole Mars’ oxygen and hydrogen and eventually its lakes, oceans and waterfalls. To this day, the solar winds continue to strip away Mars’ remaining atmosphere.
So, the aurora is not only beautiful and surreal, but it shows us in a dramatic fashion how our magnetic field is protecting us like a winter jacket from the solar winds.
Maybe I’ll buy a warmer jacket and move it up on my bucket list.
Note: NOVA on PBS has a summer series on the planets for all of those interested in these stories and more.
Angela Rieck, a Caroline County native, received her PhD in Mathematical Psychology from the University of Maryland and worked as a scientist at Bell Labs, and other high-tech companies in New Jersey before retiring as a corporate executive. Angela and her dogs divide their time between St Michaels and Key West Florida. Her daughter lives and works in New York City.