2. goodnight-lenin:

    Why would the sky look like a giant target? Airglow. Following a giant thunderstorm over Bangladesh in late April, giant circular ripples of glowing air appeared over TibetChina, as pictured above. The unusual pattern is created by atmospheric gravity waves, waves of alternating air pressure that can grow with height as the air thins, in this case about 90 kilometers up. Unlike auroras powered by collisions with energetic charged particles and seen at high latitudes, airglow is due to chemiluminescence, the production of light in a chemical reaction. More typically seen near the horizon, airglow keeps the night sky from ever being completely dark.

    (via the-actual-universe)

  4. intothegreatunknown:

    The Milky Way | Lake Tekapo, New Zealand (by Fernandez Barrett)

    (via wild-earth)

  6. Darstellung der Mondphasen. Illustration by Georg Caspar Kirchmaier, 1684
    Himmelsphäre. Illustration by Johannes Regiomontanus, 1512
    Sonnenbahn. Illustration by Johannes Zahn, 1687
    Sonnenzirkel. Illustrated by Johann Ulrich Müller, 1694
    Planetenumlaufbahnen. Illustration by Marcus Vitruvius Pollio & Walther Hermann Ryff, 1575
    Konstruktion der Mittagslinie einer Sonnenuhr. Illustration by Johann Ulrich Müller, 1694
    Zodiak. Illustration by Marcus Tullius Cicero & Ambrosius Theodosius Macrobius, 1526
    Ekliptik. Illustration by Johannes Regiomontanus, 1512


    I kind of love these circular illustrations from the Deutsche Fotothek. 

    (Click images for info)

  7. King Of The Night - © Marsel van Oosten

    (via earthlycreations)

  9. startswithabang:

    The Green Flash

    "Given a clear path to the horizon — such as over the ocean — this means that there’s a slight region of space just above the reddened Sun where only the shorter wavelength light is visible!

    And when that happens, in addition to the normal color gradient that comes with a sunset, you can also get a small, separate region above the disk of the Sun that appears yellow, green, or even blue! (And much fainter than the rest of the Sun!)”

    During sunset, the Sun appears to redden, dim, and eventually sink below the horizon. Every once in a while, a rare phenomenon emerges along with it: a green flash, where a greenish-colored beam of light appears just over the Sun. What causes it? One of the most beautiful natural phenomena our planet has to offer, explained in glorious detail.

    (via science-junkie)

  10. wapiti3:

    Musk Ox on Flickr.

    Ben Hattenbach photos (Alaskan Wildlife)
    Social behavior and reproduction
    Muskoxen live in herds of 12–24 in the winter and 8–20 in the summer. They do not hold territories, but they do mark their trails with preorbital glands. Male and female muskoxen both have separate age-based hierarchies, with mature oxen being dominant over juveniles. Dominant oxen tend to get access to the best resources and will displace subordinates from patches of grass during the winter. Muskoxen bulls assert their dominance in many different ways. One is arush and butt , in which a dominant bull rushes a subordinate from the side with its horns, and will warn the subordinate so it can have a chance to get away. Bulls will also roar, swing their heads, and paw the ground.Dominant bulls sometimes treat subordinate bulls like cows. A dominant bull will casually kick a subordinate with its foreleg, something they do to cows during mating.Dominant bulls will also mock copulate subordinates and sniff their genitals. A subordinate bull can change his status by charging a dominant bull.