10 Recent Space Discoveries 1/2 from Magdy's blog
Photo credit: Mark A. Wieczorek
Some Moon rocks brought by Apollo's teams were magnetic in nature, that means that the moon had it's own magnetic field (once upon a time) not like now, deprived of magnetic field.
A Magnetic field is generated by the what’s called a dynamo, which is caused by the fluid motion of a conducting material, such as liquid iron. In the case of the Earth’s magnetic field, this motion occurs in the planet’s outer core, and is caused by the convection of heat.
But the moon isn’t large enough for convection to take place.
the moon’s solid-rock middle layer, called its mantle, stirs up its liquid iron core. The researchers think this happens because the moon’s core and its mantle rotate around slightly different axes, and the boundary between them is not quite spherical, so their relative motion causes the fluid to mix around.
The strength of this stirring is determined by the angle between the core and the mantle, and the distance between the Earth and the moon, because the tidal gravitational tug from the Earth causes the moon’s mantle to rotate differently than the coreThis model would explain why the moon used to have a magnetic field, but no longer does. That’s because the angle between the mantle and the core has narrowed over time, while the distance between the moon and the Earth has widened, causing the tidal forces to steadily decrease. While these forces used to be enough to generate a dynamo inside the moon, they aren’t anymore.
Based on their calculations, the researchers estimate the lunar magnetic field might have lasted for about a billion years, somewhere between around 2.7 billion and 4.2 billion years ago.
“The further out the moon moves, the slower the stirring, and at a certain point the lunar dynamo shuts off,”
Source: https://sservi.nasa.gov/articles/mystery-moons-lost-magnetism-explained/
2 Galaxies 13 Billion Years Old
The early universe was an approximation of hell—a roiling, opaquely dense stew of electrons and protons. Almost half a billion years passed before the baby universe cooled down enough to allow the formation of neutrons. Shortly thereafter, the universal landscape settled further so that stars and galaxies could come into being.
A recent ultra-deep survey by the Subaru telescope—located in Hawaii and run by the National Astronomical Observatory of Japan—revealed seven of the earliest galaxies ever. Over 13 billion light-years distant, they appeared as unimaginably faint pinpricks of light. In fact, they were visible only after Subaru focused on a tiny patch of sky for over 100 hours of exposure.
Born only 700 million years after the big bang exploded everything into existence, these galaxies are among the earliest things ever observed and are among the first evidence of organization within the universe. These types of galaxies are characterized by intense hydrogen excitation and an absence of heavier elements since metals (other than minute amounts of lithium) hadn’t been blasted into existence yet by supernovae.
Termed Lyman-alpha emitters (LAE), these galaxies appeared suddenly and for (more or less) unknown reasons. LAE galaxies are prolific star-producers, and their extreme age offers insight into the evolution of the universe. However, astronomers aren’t sure if the ones captured by Subaru were newly formed or if they’d been present and were only made visible by a thinning of the cosmic gas that initially obscured them.
http://listverse.com/2015/01/05/10-recent-space-discoveries-no-one-can-explain/
Saturn’s largest moon, Titan, might be the most intriguing member of the solar system. It’s a primeval Earth, complete with an atmosphere, liquid bodies, and even suggestions of geological activity.
In 2013, the orbiting Cassini spacecraft spotted a brand new chunk of land that mysteriously appeared out of Titan’s second-largest sea, Ligeria Mare. Shortly thereafter, the “Magic Island” disappeared just as mysteriously into the translucent, –200 degree Celsius (–290 °F) methane-ethane sea. And then it reappeared again as a much larger landmass during one of Cassini’s recent radar sweeps of Titan.
The transient land confirms the supposition that Titan’s alien oceans and seas are dynamic components of an active environment, rather than static features. However, astronomers are at a loss to explain the physical processes responsible for the ephemeral landmass. Especially since it appears to have doubled in size—from 50 to 100 kilometers (30 to 60 mi) across—since it reappeared.
4 The Asteroid With Rings
All our gas giants are encircled by rings, though most of these are tenuous wisps of debris quite unlike Saturn’s massive sets of bling. And now, for the first time and quite unexpectedly, astronomers have found rings around a much smaller body. Meet Chariklo, an asteroid measuring only 250 kilometers (155 mi) across yet boasting its own ring system.
Chariklo, though the largest object in its cosmic vicinity, looked like an unremarkable chunk of space rock. Then astronomers noticed its anomalous light signature. As it eclipsed a faraway star, it caused an unanticipated dip in the amount of light reaching our telescopes. The dimming action occurred immediately before and after it crossed the star’s path, causing momentary confusion.
It turns out that Chariklo sports not one but two cosmic necklaces. Containing a good amount of frozen water, the larger of the rings hugging the planet is 7 kilometers (4 mi) wide, while the smaller is about half that size.
And while some asteroids do have “moons”—tiny satellites dancing around them—Chariklo is unique because a ring around an asteroid had never been observed. The rings’ origin is unclear, though it appears they were formed by an impact. They are either the remnants of a foreign body that shattered itself against Chariklo or pieces of Chariklo itself that blew off during the crash.
5 UV Underproduction
We pride ourselves on ascertaining the many universal balances that seem to occur throughout the cosmos. One such correlation has been observed between ultraviolet light and hydrogen, as the two have been found to coexist in well-defined proportions.
A recent survey, however, has thrown a monkey wrench into these suppositions and reported a severe underproduction of UV photons from known sources—a 400-percent discrepancy compared to predicted values. Lead author Juna Kollmeier likens it to walking into a dazzlingly bright room only to find several dim bulbs responsible for the disproportionate brilliance.
Two accepted processes produce UV radiation—unruly young stars and massive black holes—but more UV radiation exists than could have been produced by the two. Astronomers can’t explain the superfluous UV production and are forced to admit that “at least one thing we thought we knew about the present-day universe isn’t true.” That’s quite disheartening, considering that UV-hydrogen balance was believed to be very well understood. As in many times in the past, astronomers are forced back to the drawing board.
Quite mysteriously, this UV underproduction is only apparent at local distances. When looking farther off into space and time, astronomers find that their predictions hold up quite well. They’re remaining optimistic, though, since the unaccounted radiation could be the result of exotic, heretofore undiscovered processes. These possibly even involve dark matter decay.
Source:http://listverse.com/2015/01/05/10-recent-space-discoveries-no-one-can-explain/
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