*** THIS AMA IS NOW OVER, BUT I WILL CHECK BACK FROM TIME TO TIME TO ANSWER ADDITIONAL QUESTIONS. THANKS TO EVERYONE WHO PARTICIPATED. I WISH YOU CLEAR SKIES ON AUGUST 21! *** I hope you’ve got plans to experience the total solar eclipse that will cross the United States on August 21. It will be a mind-blowing, awe-inspiring, not-to-be-missed spectacle! I’ve been chasing total eclipses since I saw my first, in Aruba, in 1998. It was such a moving, addictive experience that I just had to repeat it. (You can read about my obsession/hobby here and here.) I also became fascinated with the history of eclipses, which led me to write my new book, American Eclipse: A Nation’s Epic Race to Catch the Shadow of the Moon and Win the Glory of the World. My book tells the true story of the total solar eclipse of July 29, 1878, which crossed America’s western frontier, from Montana Territory to Texas. In the nineteenth century (and even today), total eclipses were keenly important for astronomers, enabling them to probe the outer reaches of the sun and the inner reaches of the solar system. In 1878, many of the era’s great scientists traveled to Wyoming and Colorado to conduct their studies in the midday darkness. American Eclipse focuses on three remarkable individuals. Thomas Edison, age 31 and a recent celebrity due to his invention of the phonograph, traveled to Wyoming with a new device (the tasimeter) to study the sun’s corona. James Craig Watson, an astronomer at the University of Michigan, used the eclipse to search for a mysterious planet called Vulcan, which scientists believed circled the sun within the orbit of Mercury. And Maria Mitchell, professor of astronomy at Vassar College, used the eclipse for political/social purposes. She assembled an all-female expedition to Denver, to demonstrate to a skeptical public that women could equal men as scientists. I love to talk about solar eclipses! Ask me about the eclipse of 1878, the upcoming one on August 21, or anything else. I can also offer eclipse-viewing advice. I recently gave a TEDx talk about eclipse chasing, and it’s now online here. And I wrote a blog post about the August 21 eclipse for Scientific American here. I should also mention that my friends at NOVA PBS will be producing a live broadcast on Facebook during the eclipse from Irwin, Idaho. It’ll be hosted by science journalist Miles O’Brien—follow them on Facebook to get more information and updates. —David