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Astronomy Picture of the Day
Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.2012 April 12
Image Credit: ISS Expedition 30, NASA
Explanation: On another April 12th, in 1961, Soviet cosmonaut Yuri Alexseyevich Gagarin became the first human to see planet Earth from space. Commenting on his view from orbit he reported, "The sky is very dark; the Earth is bluish. Everything is seen very clearly". To celebrate, consider this recent image from the orbiting International Space Station. A stunning view of the planet at night from an altitude of 240 miles, it was recorded on March 28. The lights of Moscow, Russia are near picture center and one of the station's solar panel arrays is on the left. Aurora and the glare of sunlight lie along the planet's gently curving horizon. Stars above the horizon include the compact Pleiades star cluster, immersed in the auroral glow.
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Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
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April 12, 2012
Astronomers Zooming In on Alien "Earth-Sized" Planet System
A new observatory still under construction has given astronomers a major breakthrough in understanding a nearby planetary system that can provide valuable clues about how such systems form and evolve. The scientists used the Atacama Large Millimeter/submillimeter Array (ALMA) to discover that planets orbiting the star Fomalhaut must be much smaller than originally thought.
Their calculations also indicated the probable size of the planets -- larger than Mars but no larger than a few times the size of the Earth. This is much smaller than astronomers had previously thought. In 2008, a Hubble Space Telescope (HST) image had revealed the inner planet, then thought to be larger than Saturn, the second-largest planet in our Solar System. However, later observations with infrared telescopes failed to detect the planet.
That failure led some astronomers to doubt the existence of the planet in the HST image. Also, the HST visible-light image detected very small dust grains that are pushed outward by the star's radiation, thus blurring the structure of the dusty disk. The ALMA observations, at wavelengths longer than those of visible light, traced larger dust grains -- about 1 millimeter in diameter -- that are not moved by the star's radiation. This clearly revealed the disk's sharp edges, which indicate the gravitational effect of the two planets.
"Combining ALMA observations of the ring's shape with computer models, we can place very tight limits on the mass and orbit of any planet near the ring," said Aaron Boley, a Sagan Fellow at the University of Florida, leader of the study. "The masses of these planets must be small; otherwise the planets would destroy the ring," he added. The small sizes of the planets explain why the earlier infrared observations failed to detect them, the scientists said.
The ALMA research shows that the ring's width is about 16 times the distance from the Sun to the Earth, and is only one-seventh as thick as it is wide. "The ring is even more narrow and thinner than previously thought," said Matthew Payne, also of the University of Florida.
The ring is about 140 times the Sun-Earth distance from the star. In our own Solar System, Pluto is about 40 times more distant from the Sun than the Earth. "Because of the small size of the planets near this ring and their large distance from their host star, they are among the coldest planets yet found orbiting a normal star," Boley said.
The scientists observed the Fomalhaut system in September and October of 2011, when only about a quarter of ALMA's planned 66 antennas were available. When construction is completed next year, the full system will be much more capable. ALMA's new capabilities, however, revealed the telltale structure that had eluded earlier millimeter-wave observers.
"ALMA may still be under construction, but it already has proven to be the world's most powerful telescope for observing the Universe at millimeter and submillimeter wavelengths," said Stuartt Corder, of the National Radio Astronomy Observatory, a member of the observing team.
The effect of planets or moons in keeping a dust ring's edges sharp was first seen when the Voyager 1 spacecraft flew by Saturn in 1980 and made detailed images of that planet's ring system. One ring of the planet Uranus is confined sharply by the moons Cordelia and Ophelia, in exactly the manner the ALMA observers propose for the ring around Fomalhaut. The moons confining those planets' rings are dubbed "shepherding moons."
The Daily Galaxy via National Radio Astronomy Observatory
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Facebook recently bought Instagram for one billion dollars. Instagram is the fast, beautiful, fun way to share photos with friends and family. Instagram enables you to snap a picture, choose a filter to transform and theoretically improve its look and feel, then post to Instagram’s website. And you can share to Facebook, Twitter, and Tumblr too – it’s photo sharing, reinvented, and super easy to do. But, still, it’s reinvented; not exactly new or groundbreaking. So, why exactly didFacebook buy Instagram and why does that matter?
Facebook doesn’t need Instagram’s 30 million users.
It already has 850 million of its own. And Facebook’s ultra-simple built-in photo app is the most popular app on Facebook. So, why? Is Facebook predicting that its user acquisition rate will slow down? Don’t think so. They’ll likely hit a billion users sometime in the next year just on autopilot. Facebooks upcoming IPO guarantees that they’ll be spending most of their time and treasure on increasing revenues, not users. Of course, most of that is ad revenue. Instagram comes with users but no revenue and no obvious way to monetize their user base.
The Facebook Instagram deal looks like it’s a pure mobile play.
But, Facebook already has lots of mobile users. Well over 400 million users per month use Facebook on their mobile devices; and Facebook offers mobile apps on just about every platform. Problem is, Facebook is getting pennies on the dollar for mobile ad revenue compared to desktop ad revenue. In light of the upcoming IPO, Wall Street analysts are surely looking at this acquisition from the PoV of “how much revenue does the acquisition bring to the table v. the expense of keeping Instagram running and of course the one billion dollar price tag?”.
OK, this might be a bit of a stretch but maybe not. Facebook doesn’t own a piece of the image acquisition part of the mobile market. Instagram does. So, maybe Facebook is thinking that instead of Instagram users posting the images to Instagrams website, that users will start posting them to Facebooks timeline. That would result in more opportunities to serve ads to the desktop and of course that would increase revenues. I for one would like to see Facebooks spreadsheets on that one though since Facebook still has to recoup their one billion dollar investment and that will not be easy.
Maybe Facebook doesn’t have much of a choice?
Facebook wants a big piece of the mobile market and their current mobile offering may take too much time to develop into a revenue-generating service. Mobile image acquisition isn’t part of Facebook’s current mobile service but maybe that’s exactly what they need right now. The Instagram purchase, complete with business infrastructure and 30 million users, would instantly accelerate Facebook’s market share of the mobile market, and interface with Facebook in a way that increases Facebooks ad revenues on the desktop. Now this could be a Facebook mobile service that makes Wall Street happy. Right?
So, maybe the new Facebook Instagram service will enable users to quickly and easily take beautiful pictures, seamlessly share them to their Facebook timeline and friends, and Facebook gets to serve more ads to the desktop where they make their money. Maybe this is starting to sound like a match made in heaven. Never underestimate the Zuck.
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