Saturday, December 19, 2009

Geminid Meteor Shower No – Aurora Borealis Yes

I guess our location was to far West and North to see much of the Geminid meteor shower even though we did have good conditions. *See the update I took off web site for more info on the meteor shower.  I also added the picture taken in Norway of a bright  meteor flash from Astronomy’s photo of the day 19 December. *  The skies had cleared with the incoming cold weather and I even braved the –25F temperatures for several hours hoping to see and film a bright meteor burning as it entered earths atmosphere.

Five hours of viewing for me produced a total of 20 meteors, most 20 minutes a part.  While I didn’t see many meteors, there were several nice Aurora Borealis displays for me to enjoy and it made being out in the cold for the night worthwhile.  I even managed to film one very weak meteor in one of my Aurora pictures.


Faint meteor streak above the right ice sculpture.


Frost covered boat with the Aurora shimmering overhead.


A big wide band of green Aurora over houses.

*GEMINID METEOR UPDATE:  On Dec. 13th, Earth passed through a stream of debris from extinct comet 3200 Phaethon. The encounter produced a surge of more than 160 Geminid meteors per hour. The timing of the peak favored observers in Europe and the Middle East, many of whom said it was the finest display of Geminids they had ever seen.

Geminids are pieces of debris from a strange object called 3200 Phaethon. Long thought to be an asteroid, Phaethon is now classified as an extinct comet. It is, basically, the rocky skeleton of a comet that lost its ice after too many close encounters with the sun. Earth runs into a stream of debris from 3200 Phaethon every year in mid-December, causing meteors to fly from the constellation Gemini

Astronomy Picture of the Day-December 19, 2009


Aurora Shimmer, Meteor Flash
Credit & Copyright: Bjørnar G. Hansen,

Explanation: Northern Lights, or aurora borealis, haunted skies over the island of Kvaløya, near Tromsø Norway on December 13. This 30 second long exposure records their shimmering glow gently lighting the wintery coastal scene. A study in contrasts, it also captures the sudden flash of a fireball meteor from December's excellent Geminid meteor shower. Streaking past familiar stars in the handle of the Big Dipper, the trail points back toward the constellation Gemini, off the top of the view. Both aurora and meteors occur in Earth's upper atmosphere at altitudes of 100 kilometers or so, but aurora are caused by energetic charged particles from the magnetosphere, while meteors are trails of cosmic dust.

Tuesday, December 8, 2009

Winter Time Mirages


    A new month has started and conditions have been excellent for producing mirages. Several storm fronts have moved through the area rather quickly and over riding temperature layers have led to some spectacular mirages.


Morning Skyline to the East, Superior and Fata Morgana mirages.

     First of all, what's a mirage? They are real phenomena of atmospheric optics, caused by strong ray-bending in layers with steep thermal gradients. Because mirages are real physical phenomena, they can be photographed.  In a mirage, there is at least one inverted image of some object.

     Often a mirage contains multiple images, alternately erect and inverted. Mirages are classified according to the number and relative positions of these images. The classical mirages are:

# of Images       Name      Description

2     Inferior mirage      Inverted image below erect one

2     Superior mirage     Inverted image above erect one

3     3-image mirage     Inverted image between erect one

3+    Fata Morgana      complex alteration of distorted erect  and inverted images 


The surrounding lights lifted up in a complex Fata Morgana mirage in the cold morning air.  The mirages are caused by a sharp temperature inversion.

     We continue to have great conditions for mirages. I have posted another photo today, taken this morning of village lights 23 miles away. The lights are lifted up in five layers and you can see some of the bending of the refraction layers in the top two layers.



Above is another shot of mirages to the NE of us with objects in the Kuparuk Oilfield lifted up.


A good example of a Superior Mirage, CD North drill rig.

*A superior mirage occurs when an image of an object appears above the actual object, due to the refraction of light waves from the object down toward the eyes of the observer. Downward refraction occurs because air closer to the ground is colder, and therefore more dense, then air higher up. Superior mirages can take the form of looming, towering, and inversion, depending on the particular structure of the air column.

** The fata morgana is a complex mirage in which distant objects are distorted as well as elongated vertically. For example, a relatively flat river bank may appear to have tall cliffs and columns. The phenomenon occurs under much the same meteorological conditions as the superior mirage with inversion, and contains features of both towering and inversion.


What do you get when you combine a solar eclipse with a temperature inversion? Answer--a very strange Alaskan sunset. I took this picture from the Colville River Delta of Alaska's North Slope on March 18th 2007:


The crescent shape of the sun is caused by a partial eclipse--the Moon passed off-center in front of the sun on March 18th and 19th. This was widely seen from India, China, and the northern reaches of Alaska. The rest is a mirage....

Below is taken from when they ran the eclipse photo:

"Alaska is the place for strong mirages," explains atmospheric optics expert Les Cowley. "Often, layers of very cold air sit beneath warmer layers. Here the abnormal refraction has produced a distorted and strongly flattened partially eclipsed sun. The miraging temperature inversion layers can be seen crossing the sun and at each side."

"Conditions like these often produce green flashes," he adds, but so far no one has reported a flash to go with this eclipse.

Green flashes will be another topic covered in a future post.

Creative Commons License
Arctic Smoke Signals by James W. Helmericks is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 United States License.