1) The abolition of slavery in the United States was officially proclaimed with the ratification of the 13th Amendment to the Constitution in 1865.

2) The word "pencil" contains two vowels: E and I.

3) The word "oxygen" contains two vowels: O and E.

4) The Northern Lights, also known as the Aurora Borealis, are natural light displays that occur in the polar regions due to interactions between the Earth's magnetic field and solar particles.