The values of a, d and n are: 1  a = 1 (the first term) 2  d = 3 (the common difference between terms) 3  n = 10 (how many terms to add up)
Five planets will align in the predawn sky tomorrow, awakening Titans and office workers alike. Gulp. It must be time to unleash the Titans: five of the planets in our Solar System will align diagonally in the predawn night sky starting tomorrow morning. Mercury, Venus, Mars, Jupiter, and Saturn will all be visible with the naked eye starting January 20th and lasting until about February 20th. The last time a planetary party like this happened was in 2005. It's also slated to happen again later this year in August.
The next total solar eclipse visible from the mainland U.S. will be on August 21, 2017. The next total solar eclipse visible in the mainland United States will come on August 21, 2017. The next total eclipse after that for U.S. observers will be on April 8, 2024. Image Credit: NASA Eclipse Web Site.