Monday, December 17, 2012

All About Northern Lights

The weather has not cooperated this past few days relative to hiking.  Temperatures have been in the mid 30s and it has been raining.  As I have said in the past, this is my least favorite weather,  so I did not get outdoors to take any photographs. 

Progress continues with the online rockhounding adventures.  I am more than half way done with the first of the five segments of the second adventure.  Today I will be finishing creating a movie that describes how the Upper Peninsula land mass came to be. 

As I wind down toward launching the online rockhounding adventures, I will probably not post a blog update every day.  I am on the computer so much, that spending an hour or so every day on the blog just adds to the computer time.  So please be patient and understanding.....

For today's posting, I decided to include some more northern lights photos. 

Shawn Malone photograph

In the northern and southern areas near the poles of our planet people are often entertained by mysterious dancing lights in the night time sky. This natural phenomena is  known as 'Aurora borealis' in the north and 'Aurora australis' in the south..

These fantastic light displays appear in many colors with green being the most common. Shades of pink, red, yellow, green, blue, and violet can also be seen.  In many cases the lights appear static or move slightly, but they can also appear as scattered clouds of light to streamers, arcs, rippling curtains or shooting rays that light up the sky with an eerie glow.

The aurora lights occur when solar winds released from the Sun hit the Earth's upper atmosphere.  The charged particles in these solar winds collide with gas particles in the Earth's atmosphere.  The colors of the aurora lights correlate with the type of gas involved in the collisions.  The most common color of green is produced by oxygen molecules involved in collisions about 60 miles above the Earth (10 km). Rare, all-red auroras are produced by high-altitude oxygen at heights of up to 200 miles (330 km). Nitrogen produces blue or purplish-red aurora.

The frequency and intensity of aurora lights depends entirely on the degree of sunspot activity as well as  on the amount of solar winds released by our Sun. This connection between solar activity and auroras was first hypothesized in 1880.

The process that causes northern and southern lights starts in the atmosphere above the Sun.  The incredibly hot temperature above the Sun's surface causes molecules in the solar atmosphere to collide.  These incredibly explosive collisions tear the molecules apart, releasing free electrons and protons.  The Sun's rotation "throws" these subatomic particles into the vacuum of space as solar wind.  Most of the solar wind particles that reach Earth are deflected by our planet's magnetic field. However, our planet's magnetic field is weaker at the north and south poles, which allows some particles to enter the Earth's atmosphere and collide with gas particles. These collisions emit light that we see as aurora borealis and aurora australis.

The lights of the aurora generally extend from 80 kilometres (50 miles) to as high as 640 kilometres (400 miles) above the earth's surface.  It is important to point out that auroral activity is cyclic, peaking roughly every 11 years. The next peak period is 2013.  Since northern lights have been rare in Grand Marais these past few years, we look forward to more of these magnificent displays next year.

The best time to see northern lights is in the winter because there are longer periods of darkness and more nights that have clear skies. Usually the best time of night to check for auroral displays is around midnight.  In some cases the northern lights can go on for hours.  In other cases, they are only visible for a few minutes.

Here are some more of incredible aurora photos from the Internet.

Information and photos for this blog posting has input from:

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