(12-08-2014, 10:55 PM)Icaro Wrote: Today's APOD is a video dubbed Wanderers. It's pretty cool.

http://apod.nasa.gov/apod/ap150107.html Wrote:To celebrate 25 years (1990-2015) of exploring the Universe from low Earth orbit, the Hubble Space Telescope's cameras were used to revisit its most iconic image. The result is this sharper, wider view of the region dubbed the Pillars of Creation, first imaged by Hubble in 1995. Stars are forming deep inside the towering structures. The light-years long columns of cold gas and dust are some 6,500 light-years distant in M16, the Eagle Nebula, toward the constellation Serpens. Sculpted and eroded by the energetic ultraviolet light and powerful winds from M16's cluster of young, massive stars, the cosmic pillars themselves are destined for destruction. But the turbulent environment of star formation within M16, whose spectacular details are captured in this Hubble visible-light snapshot, is likely similar to the environment that formed our own Sun.

(01-27-2016, 10:24 AM)facettes Wrote: Source: APOD, 2016 January 27  

APOD Wrote:Explanation: What's happened to the sky? Moonlight illuminates a snowy scene in this night land and skyscape made on 2013 January from Lower Miller Creek, Alaska, USA. Overexposed near the mountainous western horizon is the first quarter Moon itself, surrounded by an icy halo and flanked left and right by moondogs. Sometimes called mock moons, a more scientific name for the luminous apparitions is paraselenae (plural). Analogous to a sundog or parhelion, a paraselene is produced by moonlight refracted through thin, hexagonal, plate-shaped ice crystals. As determined by the crystal geometry, paraselenae are seen at an angle of 22 degrees or more from the Moon. Compared to the bright lunar disk, paraselenae are faint and easier to spot when the Moon is low.

APOD Wrote:Explanation: Why would the sky glow like a giant repeating rainbow? Airglow. Now air glows all of the time, but it is usually hard to see. A disturbance however -- like an approaching storm -- may cause noticeable rippling in the Earth's atmosphere. These gravity waves are oscillations in air analogous to those created when a rock is thrown in calm water. The long-duration exposure nearly along the vertical walls of airglow likely made the undulating structure particularly visible. OK, but where do the colors originate? The deep red glow likely originates from OH molecules about 87-kilometers high, excited by ultraviolet light from the Sun. The orange and green airglow is likely caused by sodium and oxygen atoms slightly higher up. The featured image was captured during a climb up Mount Pico in the Azores of Portugal. Ground lights originate from the island of Faial in the Atlantic Ocean. A spectacular sky is visible through this banded airglow, with the central band of our Milky Way Galaxy running up the image center, and M31, the Andromeda Galaxy, visible near the top left.

APOD Wrote:Explanation: How massive can a normal star be? Estimates made from distance, brightness and standard solar models had given one star in the open cluster Pismis 24 over 200 times the mass of our Sun, making it one of the most massive stars known. This star is the brightest object located just above the gas front in the featured image. Close inspection of images taken with the Hubble Space Telescope, however, have shown that Pismis 24-1 derives its brilliant luminosity not from a single star but from three at least. Component stars would still remain near 100 solar masses, making them among the more massive stars currently on record. Toward the bottom of the image, stars are still forming in the associated emission nebula NGC 6357. Appearing perhaps like a Gothic cathedral, energetic stars near the center appear to be breaking out and illuminating a spectacular cocoon.

(04-04-2016, 05:26 PM)Parsons Wrote: I don't know how I feel about the last APOD (April 4th). When it comes to natural beauty, I appreciate only all-natural. Anything synthetic done (outside of basic brightness adjustments) ruins potentially beautiful photos for me. I think of it akin to someone graffiti-ing their own artwork all over a National Park: its already naturally beautiful, so any 'enhancements' only deface that beauty. That photo is a combination of the best aurora photo from that location and the best waterfall photo from that same location. So I would consider that in some gray area in between natural and not. I realize the conditions were extremely difficult to the point the photo may not have existed at all, so I do appreciate it exists. I just won't add it to my aurora wallpaper collection.