December 31, 2012
December 30, 2012
Sentinels of the Arctic
Who guards the north? Judging from this photograph, possibly giant trees covered in snow and ice. The picture was taken in 2011 in Finnish Lapland where weather can include sub-freezing temperatures and driving snow. Surreal landscapes sometimes result, where common trees become cloaked in white and so appear, to some, as watchful aliens. Far in the distance, behind this uncommon Earthly vista, is a more common sight - a Belt of Venus that divided a darkened from sunlit sky as the Sun rose behind the photographer. Of course, in the spring, the trees have thawed and Lapland looks much different.
Image Credit & Copyright: Niccolò Bonfadini
Explanation from: http://apod.nasa.gov/apod/ap120529.html
Pink Aurora over Crater Lake
Why is this aurora strikingly pink? When photographing picturesque Crater Lake in Oregon, USA in June 2012, the background sky lit up with auroras of unusual colors. Although much is known about the physical mechanisms that create auroras, accurately predicting the occurrence and colors of auroras remains a topic of investigation. Typically, it is known, the lowest auroras appear green. These occur at about 100 kilometers high and involve atmospheric oxygen atoms excited by fast moving plasma from space. The next highest auroras -- at about 200 kilometers up -- appear red, and are also emitted by resettling atmospheric oxygen. Some of the highest auroras visible -- as high as 500 kilometers up -- appear blue, and are caused by sunlight-scattering nitrogen ions. When looking from the ground through different layers of distant auroras, their colors can combine to produce unique and spectacular hues, in this case rare pink hues seen above. As Solar Maximum nears in 2013, particle explosions from the Sun are sure to continue and likely to create even more memorable nighttime displays.
Image Credit & Copyright: Brad Goldpaint
Explanation from: http://apod.nasa.gov/apod/ap120725.html
