There have been 91,310 days in the last 250 years, but only a few of them stand out as singularly odd. Unexplained phenomena, surprising coincidences, and, in some cases, a strange quiet, don’t happen every day — especially on a massive scale.

From the day an entire region thought the apocalypse was coming, to the day apparently nothing of note happened at all, some days really stand out.. Next time you’re having an eerie day, put it in perspective with these five dates.

May 19, 1780: New England’s Dark Day

This Friday in May started out like any other, with the sun rising and bringing daylight with it. But if you happened to be in the northeastern United States or small parts of southeastern Canada, the sky was yellow by midmorning and completely darkened by noon. This would be disorienting at best even today, but in the 18th century, without the benefit of modern science to explain what happened, it was even more harrowing. 

People left work and school and flooded into churches and taverns. Some believed it was the second coming of Christ. Others decided to stay put; one state legislator famously said, in response to his colleagues calling for adjournment, “The day of judgment is either approaching, or it is not. If it is not, there is no cause for an adjournment; if it is, I choose to be found doing my duty. I wish therefore that candles may be brought.”

The moon came out around midnight that night, much to the relief of those who thought it was judgment day. Nobody knew what caused the darkness at the time, but the likely culprit, based on reports from the period and physical evidence on older trees, was wildfire smoke blowing in from Canada.

April 18, 1930: The Slowest News Day

A day with no news seems next to impossible in today’s 24-hour news cycle, but one evening in 1930, BBC News reported that there was nothing to report — at least nothing that hit the station’s desk. When it came time for the regular 15-minute radio news bulletin at 8:45 p.m., the broadcast was very short: The announcer simply said, “There is no news.” The remainder of the 15 minutes was filled with piano music before the station returned to what was playing before, a live concert of the BBC Symphony Orchestra at the Queen’s Hall in London.

It's easy now to look back at what actually happened around the world that day, including a typhoon in the Philippines, but communication wasn’t as fast in the 1930s, and journalists relied heavily on wire services and government announcements. Even still, it was pretty rare to not have any news at all to report for the day.

April 11, 1954: The Most Boring Day, According to AI

Almost every day, major events happen somewhere in the world, and someone famous or noteworthy is born or dies on that day. But not always — and one such dull day was April 11, 1954. This is according to the artificial intelligence project True Knowledge, which indexed hundreds of millions of facts and was later sold to Amazon to help develop the Alexa product. In November 2010, computer scientist William Tunstall-Pedoe created a query to determine the single most boring day in history. The answer was April 11, 1954. The program determined that a Turkish academic was born that day — his field is electrical engineering — but reported that nothing else particularly significant happened. The AI clearly wasn’t a fan of water polo — the Hungarian water polo Olympian Attila Sudár was born on April 11, 1954.

March 12, 1951: Two Dennis the Menaces

If you’re from the United States, you may have a very different idea of the cartoon character Dennis the Menace than someone from the United Kingdom. In America, Dennis is a baby-faced blonde boy, a lovable scamp who gets into trouble but is ultimately endearing. The British Dennis the Menace, on the other hand, is a violent bully with a grumpy expression and a hunched posture. 

The weirdest part is that neither Dennis came first: They debuted at the same time, with no coordination, on March 12, 1951. The American Dennis was syndicated to 16 newspapers, while the British Dennis was in a weekly comic book magazine called The Beano. It’s a bizarre coincidence, but rarely causes confusion — when the 1993 American film Dennis the Menace was released across the pond, it was just called Dennis.

August 15-16, 1977: Aliens and Elvis

On August 15, 1977, the Big Ear radio telescope at the University of Ohio was trained on the cosmos, ready to catch a signal from some kind of extraterrestrial intelligence, should it exist. That day, it picked up what astronomers now know as the “Wow!” signal, a strange radio signal at a frequency and volume they’d been looking for. It’s still the most compelling example of a potential extraterrestrial communication — and while the general consensus now is that it was something other than alien life, nobody knows for sure what that is.

In 1977, SETI researchers were wowed by what they’d picked up, and the astronomy community was buzzing. But it was a busy 24 hours, and the world’s eyes were on a different type of star. On August 16, Elvis Presley died, setting off a firestorm of media coverage and national mourning. While there are many conspiracy theories around the death of the King, surprisingly (given the timing), most of them don’t involve aliens.