Los Angeles, August 20 : Twilight will fall at midday on Monday, stars will glimmer and birds will roost in an eerie stillness as millions of Americans and visitors witness the first total solar eclipse to traverse the United States from coast to coast in 99 years. The sight of the moon’s shadow passing directly in front of the sun, blotting out all but the halo-like solar corona, may draw the largest live audience for a celestial event in human history. When those watching via broadcast and online media are factored into the mix, the spectacle will likely smash records.”It will certainly be the most observed total eclipse in history,” astronomer Rick Fienberg of the American Astronomical Society (AAS) said last week.The eclipse begins its cross-country trajectory over the Pacific Coast of Oregon in late morning. It will reach South Carolina’s Atlantic shore some 90 minutes later.The total eclipse of the sun is considered one of the most spell-binding phenomena in nature but it rarely occurs over a wide swath of land, let alone one of the world’s most heavily populated countries at the height of summer.In terms of audience potential, it is hard to top the United States, with its mobile and affluent population, even though the direct path is mostly over rural areas, towns and small cities.The largest is Nashville, Tennessee, a city of 660,000 residents.Even so the advent of social media and inexpensive high-tech optics have boosted public awareness, assuring what many US experts predict will be unprecedented viewership for the so-called “Great American Eclipse.”