The nebular hypothesis is the most widely accepted model in cosmogony explaining the formation and evolution of the Solar System, which suggests that it formed from nebulous material in space. The hypothesis offers explanations for some of the Solar System's properties, including the nearly circular and coplanar orbits of the planets, and their motion in the same direction as the Sun's rotation. According to the hypothesis, Sun-like stars form over about 100 million years, in massive, gravitationally unstable clouds of molecular hydrogen (giant molecular clouds). Matter coalesces to smaller, denser clumps within, which then proceed to both rotate and collapse, forming stars. Star formation produces a gaseous protoplanetary disk around the young star, which may give birth to planets (protoplanetary disk pictured in the Orion Nebula). The formation of planetary systems is thought to be a natural result of star formation, with dense terrestrial planets forming closer to the star and colder giant planets forming further away, beyond the so-called frost line. Originally applied only to our own Solar System, the nebular hypothesis is now thought to be at work throughout the universe.

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

_______________________________ Today's selected anniversaries:

1774:

In response to the British Parliament enacting the Intolerable Acts, representatives from twelve of Britain's North American colonies convened the First Continental Congress at Carpenters' Hall in Philadelphia. https://en.wikipedia.org/wiki/First_Continental_Congress

1793:

French Revolution: The National Convention began the Reign of Terror, a ten-month period of systematic repression and mass executions by guillotine of perceived enemies within the country. https://en.wikipedia.org/wiki/Reign_of_Terror

1914:

World War I: The First Battle of the Marne began with French forces engaging the advancing German army at the Marne River near Paris. https://en.wikipedia.org/wiki/First_Battle_of_the_Marne

1945:

Cold War: Soviet cipher clerk Igor Gouzenko defected to Canada with over 100 documents on Soviet espionage activities and sleeper agents. https://en.wikipedia.org/wiki/Igor_Gouzenko

1977:

NASA launched the robotic space probe Voyager 1 (pictured), currently the farthest spacecraft from Earth. https://en.wikipedia.org/wiki/Voyager_1

_____________________________ Wiktionary's word of the day:

canard: A false or misleading report or story, especially if deliberately so. https://en.wiktionary.org/wiki/canard

___________________________ Wikiquote quote of the day:

I succeeded by saying what everyone else is thinking.     In the mystic traditions of the different religions we have a remarkable unity of spirit. Whatever religion they may profess, they are spiritual kinsmen. While the different religions in their historic forms bind us to limited groups and militate against the development of loyalty to the world community, the mystics have already stood for the fellowship of humanity in harmony with the spirit of the mystics of ages gone by.   --Sarvepalli Radhakrishnan https://en.wikiquote.org/wiki/Sarvepalli_Radhakrishnan