Planet Nine is a hypothetical planet in the outer region of the Solar System. Its gravitational effects could explain the unlikely clustering of orbits for a group of extreme trans-Neptunian objects, bodies with average distances from the Sun that are more than 250 times that of Earth. These objects tend to make their closest approaches to the Sun in one sector, and their orbits are similarly tilted. Their improbable alignments suggest that an undiscovered planet may be shepherding the orbits of the most distant known Solar System objects. Planet Nine would have a predicted mass five to ten times that of Earth, and an elongated orbit extending 400 to 800 times as far from the Sun as the Earth's. It may have been ejected from its original orbit by Jupiter during the genesis of the Solar System, wrested from another star, captured as a rogue planet, or pulled into an eccentric orbit by a passing star.

Read more: https://en.wikipedia.org/wiki/Planet_Nine

_______________________________ Today's selected anniversaries:

1917:

First World War: The Canadian Corps began the first wave of attacks at the Battle of Vimy Ridge in Vimy, France. https://en.wikipedia.org/wiki/Battle_of_Vimy_Ridge

1942:

World War II: Japanese forces defeated Allied troops at the Battle of Bataan on the Bataan Peninsula in the Philippines before beginning to forcibly transfer more than 90,000 prisoners of war to prison camps in the Bataan Death March. https://en.wikipedia.org/wiki/Bataan_Death_March

1959:

NASA announced the selection of the Mercury Seven, the first astronauts in Project Mercury. https://en.wikipedia.org/wiki/Mercury_Seven

1999:

President of Niger Ibrahim Baré Maïnassara was shot to death by soldiers in Niamey. https://en.wikipedia.org/wiki/Ibrahim_Bar%C3%A9_Ma%C3%AFnassara

_____________________________ Wiktionary's word of the day:

grandfather: 1. (transitive, chiefly US, law) To retain existing laws or rules for (a person or organization previously affected by them). 2. (intransitive, chiefly US, law) To retain existing laws or rules only for people or organizations previously affected by them, and to apply new laws or rules to the unaffected people or organizations. https://en.wiktionary.org/wiki/grandfather

___________________________ Wikiquote quote of the day:

No one is more dangerous than someone who thinks he has "The Truth". To be an atheist is almost as arrogant as to be a fundamentalist.   --Tom Lehrer https://en.wikiquote.org/wiki/Tom_Lehrer