In 1776, the solar system only had 6 planets. Now, it has 8. Does it end there?

Over the past 250 years, the number of "planets" in our solar system has ranged from six to nine — and, briefly, even 11 — depending on what astronomers knew at the time and how they defined a planet. As the United States prepares to celebrate its 250th anniversary, that changing tally offers a unique lens on humanity's evolving understanding of the cosmos since 1776.Throughout history, astronomers have discovered new worlds, identified entirely new classes of celestial objects and r