D.O.C. The Search for Planets

The Search for Planets


Planets are large objects in space. Planets travel around the sun. Early astronomers searched the sky to find planets. In earlier times, peoples thought there were six planets. They knew about Earth, Mars, and Venus. They knew about Mercury, Jupiter and Saturn. Was there anything else out there? Early telescopes were too weak to spot other planets.
March 13, 1781, was an important day. F. William Herschel and Caroline L. Herschel discovered a seventh planet. They called it Uranus. They wondered if there were still more planets out in space. Some people thought so. They kept looking because they were curious.
Jean J. Le Verrier thought he knew where another planet was. He asked Johanne G. Galle and Heinrich L. d’Arrest to look for it. That very night, they thought they saw something. What was it? By the next night, they knew that it was a planet. Thanks to their work, Neptune became the eighth known planet on September 24, 1846.
What was beyond Neptune? Dr. Clyde W. Tombaugh found out. He discovered Pluto on February 18, 1930. It became the ninth know planet. We have since learned that Pluto is very small. We now call Pluto a “dwarf planet.” If all goes well, a spacecraft will fly past Pluto in 2016. It will take pictures of the planet. The pictures should tell us what the surface of Pluto is like. Are there more planets beyond Pluto? What do you think?