Orion, the hunter, is a constellation, and constellations are not "discovered" in the sense of finding something new. They are patterns of stars that humans have recognized and named for thousands of years.

Orion is one of the oldest recognized constellations, with records of it dating back to at least:

* 3,000 BC: In Mesopotamia, where it was known as "The Ploughman."

* 2,000 BC: In ancient Egypt, where it was associated with the god Osiris.

So, while we can't pinpoint an exact "discovery" date, it's safe to say that Orion has been known and recognized for at least 5,000 years.