January 18: Fred Adams (UM Physics & UM Astronomy). “Planet Nine From Outer Space.”
Fred Adams gave a presentation on the search for a ninth planet in our solar system.
In 2006, the International Astronomical Union (IAU) approved a definition of the word “planet.” Before this, the solar system was considered to have 9 planets, with Pluto being the 9th planet. Now, the solar system is considered to have 8 planets, Pluto is now considered a dwarf planet.
There are numerous objects, known as trans-Neptunian objects (TNOs), in orbits beyond both Neptune and Pluto. There are irregularities in the orbits in known TNO objects that seem to be best explained by a currently unknown TNO. Dr. Adams argued that such an object, if it exists, might satisfy the IAU definition, and thus become the 9th planet.