That was likely June 1783 in Annonay, France when the Montgolfier brothers, Joseph and Jacques successfully launched the first successful hot air balloon. Their balloon was 10 meters (32.8 ft.) in diameter and rose to 2000 meters (6,562 ft.). Because a man made flying object had not been seen before, you can imagine the awe of those who happened looked up in the surrounding villages and fields.
aliens were fist discovered in 1917
the first vampire sighting was in 0001bc.
Area 51
That was prior to written history so there is no record of the first sighting.
I worked there for 10 years, it is where the military developes their most secret technology so it is away from prying eyes. Not a single alien sighting in all that time.
The first written sighting of the Northern Lights was reported to be in 2600 B.C
the first sighting was in 1,000,907 BC so yeah that's when it occured.
Yes, many.
Area 51 is in Nevada.
Area 51 got its name from its location on a grid map. The U.S. Geological Survey designated the area as "Area 51" because it simply corresponds to its location on a grid in the Nevada Test and Training Range. It was not officially acknowledged until the CIA publicly acknowledged its existence in 2013.
565 AD
Well a Kraken is a mythological creature, so there never was a first sighting of something that didn't exist. But it was seen in Pirate's of the Caribbean ;)
No one revealed Area 51.