2 Dollars - Charles III WOW! signal

The WOW! signal was a narrowband radio transmission detected on August 15, 1977, by astronomer Jerry Ehman at Ohio State University's Big Ear radio telescope. Ehman circled the printout and wrote "Wow!" in the margin — the annotation that named it permanently. The signal lasted 72 seconds, matched the expected profile of an extraterrestrial transmission almost perfectly, and has never been detected again despite decades of follow-up observation.

Big Ear itself was demolished in 1997 to make way for a golf course expansion.