Neptune's windy atmosphere in August 1989. The ice giant Neptune was the first planet located through mathematical predictions rather than through regular observations of the sky.
well slavery was an big issue because it separated the northern and southern states. the northern states realize that slavery was an unnessary inhumane treatment and wanted to abolished it. While the southern states depended on slaves since they worked for free on their plantation. To resolve this they counted 3 free men for 5 slaves until 1808.
The letting of residents in the territories decide the question of slavery for themselves. This was a major issue in the debate of the territories in the west in deciding which states will ban or keep slavery.