However, just in case you missed it, this is a thumbnail reminder of a must see image of the Sun.
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| © Alan Friedman (Averted Imagination) |
Wednesday, March 14, 2012
Really Angry Bird
However, just in case you missed it, this is a thumbnail reminder of a must see image of the Sun.
Friday, March 9, 2012
Dust Devil in Mars
Dust Snake Devil on Mars
California Institute of Technology
What a camera! What an amazing image!
Click here to see the large image in all its glorious detail.
A towering dust devil, casts a serpentine shadow over the Martian surface in this image acquired by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter.
The scene is a late-spring afternoon in the Amazonis Planitia region of northern Mars. The view covers an area about four-tenths of a mile (644 meters) across. North is toward the top. The length of the dusty whirlwind's shadow indicates that the dust plume reaches more than half a mile (800 meters) in height. The plume is about 30 yards or meters in diameter.
A westerly breeze partway up the height of the dust devil produced a delicate arc in the plume. The image was taken during the time of Martian year when the planet is farthest from the sun. Just as on Earth, winds on Mars are powered by solar heating. Exposure to the sun's rays declines during this season, yet even now, dust devils act relentlessly to clean the surface of freshly deposited dust, a little at a time.
NASA
The scene is a late-spring afternoon in the Amazonis Planitia region of northern Mars. The view covers an area about four-tenths of a mile (644 meters) across. North is toward the top. The length of the dusty whirlwind's shadow indicates that the dust plume reaches more than half a mile (800 meters) in height. The plume is about 30 yards or meters in diameter.
A westerly breeze partway up the height of the dust devil produced a delicate arc in the plume. The image was taken during the time of Martian year when the planet is farthest from the sun. Just as on Earth, winds on Mars are powered by solar heating. Exposure to the sun's rays declines during this season, yet even now, dust devils act relentlessly to clean the surface of freshly deposited dust, a little at a time.
NASA
Thursday, March 8, 2012
Supernova and Sun
Multiwavelength X-ray, infrared, and optical compilation image of
Kepler's supernova remnant, SN 1604.
While studying the Barnard 68 dark nebula I understood that such clouds collapse by time and start to heat up while falling inside pulled by gravity. I was thinking that maybe something heavy inside such cloud could perhaps trigger a collapse of the cloud.
But the Khan Academy lecture on the formation of Earth suggests something else - not just a cloud collapsing by time or anything inside the cloud but rather a strong push from outside.
The idea is that there may have been a supernova explosion that caused a powerful pressure wave. This caused the molecular cloud to compress giving gravity something to do forming both the Sun and the planetary disk and enough heat for heavier atoms to form all the way to uranium.
So instead of a quiet hiss the Sun would have started with a rather big bang in the near neighbourhood of the dark nebula that is our cold mother.
I am not at all qualified to decide what happened by myself but a very eager student to learn more about the origins of our Solar system.
Supernova
A supernova is a stellar explosion Solitary stars with a mass below approximately 9 solar masses, such
as the Sun, evolve into white dwarfs without ever becoming supernovae.
Supernovae are extremely luminous and cause a burst of radiation that often briefly outshines an entire galaxy, before fading from view over several weeks or months. During this short interval a supernova can radiate as much energy as the Sun is expected to emit over its entire life span.
The explosion expels much or all of a star's material at a velocity of up to 30,000 km/s (10% of the speed of light), driving a shock wave into the surrounding interstellar medium. This shock wave sweeps up an expanding shell of gas and dust called a supernova remnant.
Several types of supernovae exist.
Types I and II can be triggered in one of two ways, either turning off or suddenly turning on the production of energy through nuclear fusion. After the core of an aging massive star ceases generating energy from nuclear fusion, it may undergo sudden gravitational collapse into a neutron star or black hole, releasing gravitational potential energy that heats and expels the star's outer layers.
Alternatively a white dwarf star may accumulate sufficient material from a stellar companion (either through accretion or via a merger) to raise its core temperature enough to ignite carbon fusion, at which point it undergoes runaway nuclear fusion, completely disrupting it.
Although no supernova has been observed in the Milky Way since Kepler's Supernova 1604, supernovae remnants indicate on average the event occurs about once every 50 years in the Milky Way.
They play a significant role in enriching the interstellar medium with higher mass elements.
Furthermore, the expanding shock waves from supernova explosions can trigger the formation of new stars.
from wikipedia
There you have it!
Supernovae are extremely luminous and cause a burst of radiation that often briefly outshines an entire galaxy, before fading from view over several weeks or months. During this short interval a supernova can radiate as much energy as the Sun is expected to emit over its entire life span.
The explosion expels much or all of a star's material at a velocity of up to 30,000 km/s (10% of the speed of light), driving a shock wave into the surrounding interstellar medium. This shock wave sweeps up an expanding shell of gas and dust called a supernova remnant.
Several types of supernovae exist.
Types I and II can be triggered in one of two ways, either turning off or suddenly turning on the production of energy through nuclear fusion. After the core of an aging massive star ceases generating energy from nuclear fusion, it may undergo sudden gravitational collapse into a neutron star or black hole, releasing gravitational potential energy that heats and expels the star's outer layers.
Alternatively a white dwarf star may accumulate sufficient material from a stellar companion (either through accretion or via a merger) to raise its core temperature enough to ignite carbon fusion, at which point it undergoes runaway nuclear fusion, completely disrupting it.
Although no supernova has been observed in the Milky Way since Kepler's Supernova 1604, supernovae remnants indicate on average the event occurs about once every 50 years in the Milky Way.
They play a significant role in enriching the interstellar medium with higher mass elements.
Furthermore, the expanding shock waves from supernova explosions can trigger the formation of new stars.
from wikipedia
"The expanding shock waves from supernova explosions can trigger the formation of new stars."
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