The Clermont steamboat by Robert Fulton made its maiden trip up the Hudson River.
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King Charles IX of France became an adult on his 13th birthday.
Asaph Hall discovered Mars' second moon, called Phobos.
Younes Abouyaaqoub drove a van into pedestrians on La Rambla in Barcelona, Spain, killing 14 people and injuring at least 130 others.
Pope Leo II became the bishop of Rome.
American swimmer Michael Phelps became the first person to win eight gold medals at one Olympic Games.
