Apple Inc became the largest company in the world.
On this day, its value reached over $600 billion.
Source
Halley's Comet made its closest approach to Earth in recorded history.
The UK, Ireland, and Northern Ireland governments signed the Good Friday Agreement.
The first photo of a black hole that was taken in 2017 was announced to the public.
The Titanic departed Southampton for its first and only journey.
Arbor Day was celebrated for the first time in America in Nebraska.
