Image credit & copyright: Mikey MacKinven (Mikey Mack).
Happy Friday everyone! Let’s get our weekend off to a dazzling start with this image from Mikey MacKinven of the beautiful Aurora Australis (Southern Lights) over Lake Mapourika along the West Coast of New Zealand’s Southern Island.
You may not be familiar with the Southern Lights but they’re the beautiful Southern Hemisphere counterpart to the Northern Hemisphere’s, Northern Lights. I’ll explain a bit below. So what else do you see in the sky in this incredible image? How about that tiny 7,000 light year diameter cloud, 200,000 light years away beyond the colors and the screen of stars? Of course, that’s the Small Magellanic Cloud (SMC), a satellite galaxy to our own Milky Way. What about that tiny point of light next to it? That’s 47 Tucanae; a large globular star cluster 120 light years in diameter and at a distance of roughly 14,800 light years, it’s much closer to us that the SMC.
So what about the aurora; how to they work? It all starts with the Sun. Our home star turns its sights toward Earth and fires off material in the form of a Coronal Mass Ejection (CME). Roughly two days later (35-45 hours-ish) that material impacts Earth’s magnetosphere, follows the magnetic fields to where they converge at Earth’s magnetic poles.
The stronger the CME, the more powerful the event, and the more powerful the event, the further from the poles you are able to see the aurora. Weak Aurora Borealis (Northern Hemisphere) won’t travel much past the Arctic Circle but are often seen in Canada. High energy events can sometimes be seen all the way down to places like Northern California and points across Europe. Weaker Aurora Australis (Southern Lights) usually don’t go much past the Antarctic Circle. High energy events can create aurora in Australia, New Zealand and South Africa. Auroral events take place at the Northern and Southern magnetic poles simultaneously but viewing depends on many factors to include, day or night, weather, magnitude of the event and seasons.
The colors associated with aurora have to do with which atomic oxygen or nitrogen molecules charged particles contact when they hit Earth’s atmosphere which can happen anywhere from 32 km (20 mi.) to 321 km (200 mi.) in altitude.
Here’s a very basic breakdown:
Red: Above 150 mi. when charged particles interact with oxygen.
Green: Up to 150 mi. when charged particles interact with oxygen.
Violet: Above 60 mi. when charged particles interact with nitrogen.
Blue: Up to 60 mi. when charged particles interact with nitrogen.
Mikey MacKinven: http://www.mackphotography.co.nz/