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 Three-fifths Compromise gave the otherwise small white  populations of the South an equal footing with the more populous  North, and this compromise held until the basic issue of slavery  became paramount in the 1820s and 1830s.