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This has been a glorious week for solar observers! Led by large sunspot region AR1339, the sun's disk is alive with activity... the most dynamic show in many years. I made two interpretations - which do you prefer? A close-up view of 1339 can be seen here . This image was featured on NASA's Astronomy Picture of the Day .
digg On March 10, 1869, railroad officials, political leaders and work gangs converged at Promontory Point, Utah, to drive in the last spike of the Pacific Railroad, the first of five transcontinental railroads built in the 19th century. The driving of the spike linked the Union Pacific line built from East to West with the Central Pacific, which had commenced construction in California. On January 28, 1986, after about 73 seconds into its launch, space shuttle Challenger exploded, leading to the deaths of its seven crew members, which included the first teacher in space. The first transcontinental telegraph line went into operation 149 years ago on October 24, 1861, when the gap between the country’s eastern and western networks was closed.