Thoday's APOD is a very interesting image in many ways.
Another example of a blue-looking Tarantula Nebula.
Photo: Jonathan Green, Amit Kamble.
Full resolution here.
Note in the APOD a bright blue "star" in the Large Magellanic Cloud. That would be R136
, the brilliant star cluster that ionizes the tremendous emission nebula, the Tarantula Nebula
. While the Tarantula Nebula would normally look pink, even in an RGB image, it is clear that the star cluster is so much brighter than the nebula that it is no wonder if the blue stars outshine the red nebula in a low-resolution image like the APOD, particularly since it seems certain that no Hα filter has been used for it. After all, the astrophotographer's goal was to capture the aurora in the sky and make it a part of the skyscape which includes the Milky Way and the Magellanic Clouds and some bright stars and nebulas, not to resolve the deep-sky objects in stunning detail.
Another example of a blue-looking Tarantula Nebula can be seen at left, and there are other examples, too.
Another striking detail in today's APOD is the very great difference between the Large and the Small Magellanic Clouds. Usually, color pictures show these galaxies to be moderately similar in brightness, although different in size. But in this image, the Small Magellanic Cloud looks downright emaciated compared with its big bully of a neighbor.
I really like the annotation of the APOD, and I particularly appreciate that 47 Tucanae has been pointed out, just south of the Small Magellanic cloud. 47 Tucanae is the second brightest globular of the Milky Way, so it certainly deserves attention.
However, the brightest Milky Way globular of them all is also in the picture, and it was overlooked! Omega Centauri
is the fuzzy whitish blob in the upper left part of the picture, to the left of the Coalsack and the Southern Cross.
And of course... even I like the aurora a lot! I like the way it shimmers and changes color between orange, brick red, pink and purple.