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Public release date: 11-Mar-2013[ | E-mail |
Share ] Contact: Susan Hendrix
Susan.m.hendrix@nasa.gov
301-286-7745
NASA/Goddard Space Flight Center
On March 2, 2013, NASA's Solar Dynamics Observatory (SDO) entered its semiannual eclipse season, a period of three weeks when Earth blocks its view of the sun for a period of time each day. On March 11, however, SDO was treated to two transits. Earth blocked SDO's view of the sun from about 2:15 to 3:45 a.m. EDT. Later in the same day, from around 7:30 to 8:45 a.m. EDT, the moon moved in front of the sun for a partial eclipse.
When Earth blocks the sun, the boundaries of Earth's shadow appear fuzzy, since SDO can see some light from the sun coming through Earth's atmosphere. The line of Earth appears almost straight, since Earth -- from SDO's point of view -- is so large compared to the sun.
The eclipse caused by the moon looks far different. Since the moon has no atmosphere, its curved shape can be seen clearly, and the line of its shadow is crisp and clean. Any spacecraft observing the sun from an orbit around Earth has to contend with such eclipses, but SDO's orbit is designed to minimize them as much as possible, with only two three-week eclipse seasons each year. The 2013 spring eclipse season continues until March 26. The fall season will begin on Sept. 2.
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Public release date: 11-Mar-2013[ | E-mail |
Share ] Contact: Susan Hendrix
Susan.m.hendrix@nasa.gov
301-286-7745
NASA/Goddard Space Flight Center
On March 2, 2013, NASA's Solar Dynamics Observatory (SDO) entered its semiannual eclipse season, a period of three weeks when Earth blocks its view of the sun for a period of time each day. On March 11, however, SDO was treated to two transits. Earth blocked SDO's view of the sun from about 2:15 to 3:45 a.m. EDT. Later in the same day, from around 7:30 to 8:45 a.m. EDT, the moon moved in front of the sun for a partial eclipse.
When Earth blocks the sun, the boundaries of Earth's shadow appear fuzzy, since SDO can see some light from the sun coming through Earth's atmosphere. The line of Earth appears almost straight, since Earth -- from SDO's point of view -- is so large compared to the sun.
The eclipse caused by the moon looks far different. Since the moon has no atmosphere, its curved shape can be seen clearly, and the line of its shadow is crisp and clean. Any spacecraft observing the sun from an orbit around Earth has to contend with such eclipses, but SDO's orbit is designed to minimize them as much as possible, with only two three-week eclipse seasons each year. The 2013 spring eclipse season continues until March 26. The fall season will begin on Sept. 2.
###
[ | E-mail | Share ] ?
AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert! system.
Source: http://www.eurekalert.org/pub_releases/2013-03/nsfc-nso031113.php
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Google Research just launched its Wikilinks corpus, a massive new data set for developers and researchers that could make it easier to add smart disambiguation and cross-referencing to their applications. The data could, for example, make it easier to find out if two web sites are talking about the same person or concept, Google says. In total, the corpus features 40 million disambiguated mentions found within 10 million web pages. This, Google notes, makes it “over 100 times bigger than the next largest corpus,” which features less than 100,000 mentions. For Google, of course, disambiguation is something that is a core feature of the Knowledge Graph project, which allows you to tell Google whether you are looking for links related to the planet, car or chemical element when you search for ‘mercury,’ for example. It takes a large corpus like this one and the ability to understand what each web page is really about to make this happen. To construct this data set, Google looked at links to Wikipedia pages “where the anchor text of the link closely matches the title of the target Wikipedia page.” There is a high probability, that this anchor text is a mention of the corresponding entity that’s the focus of the entity that’s discussed in the Wikipedia entry. The 10 million annotated web pages, sadly, aren’t part of the corpus because of copyright issues, but the UMass Wikilinks project features all the necessary tools to create this data from scratch. The UMass team also published a paper that explains the process that was used to create this data set in more detail (PDF). Last year, Google released a similar data set when it launched a database with over 7.5 million concepts and 175 million unique text strings that is similar to what Google itself uses to suggest targeted keywords for advertisers. That set, too, was built by looking at Wikipedia articles to identify concepts and the anchor links that other websites used to link to them.
