Sagan ride.
Zodiacal Light and the False Dawn
Explanation: Is it dawn or false dawn? During certain times of the year, the horizon near the rising Sun will begin to glow unusually early. This early glow does not originate directly from the Sun, but rather from sunlight reflected by interplanetary dust. Calledzodiacal light, the glowing triangle of light may be mistaken, for a while, for a sunrise, and so may be called a false dawn. Pictured above, two false dawns were recorded in time lapse movies each spanning about five hours from the perch of the highest observatory in the world: Mount Saraswati near Hanle, India. At its brightest, the rising zodiacal triangle on the left glows brighter than even the central disk of our Milky Way Galaxy — visible as the diagonal band moving left to right across the frame.
Image Credit & Copyright: Nilesh Vayada & Ajay Talwar (TWAN)
A Full Sky Aurora Over Norway
Explanation: Higher than the highest building, higher than the highest mountain, higher than the highest airplane, lies the realm of the aurora. Aurorae rarely reach below 60 kilometres, and can range up to 1000 kilometres. Aurora light results from energeticelectrons and protons striking molecules in the Earth’s atmosphere. Frequently, when viewed from space, a complete aurora will appear as a circle around one of the Earth’s magnetic poles. The above wide angle image, horizontally compressed, captured anunexpected auroral display that stretched across the sky one month ago over eastern Norway.
Image Credit & Copyright: Sebastian Voltmer
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The Supernovae
Fate has something very different, and very dramatic, in store for stars which are some 5 or more times as massive as our Sun. After the outer layers of the star have swollen into a red supergiant (i.e., a very big red giant), the core begins to yield to gravity and starts to shrink.
As it shrinks, it grows hotter and denser, and a new series of nuclear reactions begin to occur, temporarily halting the collapse of the core. However, when the core becomes essentially just iron, it has nothing left to fuse (because of iron’s nuclear structure, it does not permit its atoms to fuse into heavier elements) and fusion ceases. In less than a second, the star begins the final phase of its gravitational collapse.
The core temperature rises to over 100 billion degrees as the iron atoms are crushed together. The repulsive force between the nuclei overcomes the force of gravity, and the core recoils out from the heart of the star in an explosive shock wave. As the shock encounters material in the star’s outer layers, the material is heated, fusing to form new elements and radioactive isotopes.
Boom!
In one of the most spectacular events in the Universe, the shock propels the material away from the star in a tremendous explosion called a supernova. The material spews off into interstellar space — perhaps to collide with other cosmic debris and form new stars, perhaps to form planets and moons, perhaps to act as the seeds for an infinite variety of living things.
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Baby Solar System: 3 Alien Planets Smaller Than Earth Found
Astronomers have discovered the three smallest alien planets yet, including one that’s just the size of Mars.
Imaged Above: This artist’s concept depicts the newfound planetary system KOI-961, which contains three alien planets smaller than Earth. The exoplanets circle their red-dwarf host star at very close distances, so they’re likely too hot to host life. Credit: NASA/JPL-Caltech
The alien worlds, detected using publicly available data from NASA’s Kepler mission, are 0.78, 0.73 and 0.57 times the diameter of Earth, respectively; the smallest one is roughly Mars-size. The three exoplanets orbit a red dwarf star known as KOI-961, which is just one-sixth the size of our sun and is located 120 light-years away, in the Constellation Cygnus (The Swan).
“This is the tiniest solar system found so far,” said principal investigator John Johnson of the California Institute of Technology in Pasadena. “It’s actually more similar to Jupiter and its moons in scale than any other planetary system. The discovery is further proof of the diversity of planetary systems in our galaxy.”
A Mini Planetary System
The three planets orbit very close to their star, just 0.6 to 1.5 percent the distance from Earth to the sun. It takes each of them less than two days to zip around KOI-961, researchers said.
“It’s almost like you took a shrink gun and zapped a planetary system, the whole thing, including the sun,”
All three exoplanets are thought to be rocky like Earth. However, their closeness to their star makes them too hot to be in the habitable zone, the area around a star neither too hot nor too cold for liquid water to exist on the surface.
