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.
Clock how the world will celebrate October 21 - the date that Marty McFly visited in Back to the Future II. There have been more than a few hoax attempts over the past few years, but the big day is finally here - tomorrow is October 21, 2015, which is when Marty McFly and Doc Brown went into the future in Back To The Future II.