What Would Happen if We Didn't Have Leap Years?

In a leap year, we add this extra day to the month of February, making it 29 days long instead of the usual 28
In a leap year, we add this extra day to the month of February, making it 29 days long instead of the usual 28
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What Would Happen if We Didn't Have Leap Years?

In a leap year, we add this extra day to the month of February, making it 29 days long instead of the usual 28
In a leap year, we add this extra day to the month of February, making it 29 days long instead of the usual 28

You may be used to hearing that it takes the Earth 365 days to make a full lap, but that journey actually lasts about 365 and a quarter day. Leap years help to keep the 12-month calendar matched up with Earth’s movement around the Sun. After four years, those leftover hours add up to a whole day.

In a leap year, we add this extra day to the month of February, making it 29 days long instead of the usual 28.

The idea of an annual catch-up dates back to ancient Rome, where people had a calendar with 355 days instead of 365 because it was based on cycles and phases of the Moon. They noticed that their calendar was getting out of sync with the seasons, so they began adding an extra month, which they called Mercedonius, every two years to catch up with the missing days.

In the year 45 B.C.E., Roman emperor Julius Caesar introduced a solar calendar, based on one developed in Egypt. Every four years, February received an extra day to keep the calendar in line with the Earth’s journey around the Sun.

In honor of Caesar, this system is still known as the Julian calendar. As time went on, people realized that the Earth’s journey wasn’t exactly 365.25 days – it actually took 365.24219 days, which is about 11 minutes less. So, adding a whole day every four years was actually a little more correction than was needed.

In 1582, Pope Gregory XIII signed an order that made a small adjustment. There would still be a leap year every four years, except in “century” years – years divisible by 100, like 1700 or 2100 – unless they were also divisible by 400.

It might sound a bit like a puzzle, but this adjustment made the calendar even more accurate – and from that point on, it was known as the Gregorian calendar, as reported by Science Alert and The Conversation.

What if we didn’t have leap years?

If the calendar didn’t make that small correction every four years, it would gradually fall out of alignment with the seasons. Over centuries, this could lead to the solstices and equinoxes occurring at different times than expected. Winter weather might develop in what the calendar showed as summer, and farmers could become confused about when to plant their seeds.

Without leap years, our calendar would gradually become disconnected from the seasons. Other calendars around the world have their own ways of keeping time. The Jewish calendar, which is regulated by both the Moon and the Sun, is like a big puzzle with a 19-year cycle. Every now and then, it adds a leap month to make sure that special celebrations happen at just the right time. The Islamic calendar is even more unique. It follows the phases of the Moon and doesn’t add extra days. Since a lunar year is only about 355 days long, key dates on the Islamic calendar move 10 to 11 days earlier each year on the solar calendar. For example, Ramadan, the Islamic month of fasting, falls in the ninth month of the Islamic calendar. In 2024, it will run from March 11 to April 9; in 2025, it will occur from March 1-29; and in 2026, it will be celebrated from February 18 to March 19.

Learning from the planets

Astronomy originated as a way to make sense of our daily lives, linking the events around us to celestial phenomena.

The concept of leap years exemplifies how humans have existed. Some ancient methods, such as astrometry and lists of astronomical objects, persist even today, revealing the timeless essence of our quest to understand nature. People who do research in physics and astronomy are inherently curious about the workings of the universe and our origins. In the grand scheme, our lives occupy a mere second in the vast expanse of space and time – even in leap years when we add that extra day.



Greece's 'Instagram Island' Santorini nears Saturation Point

Tourists queue as they wait to take a picture from one of the balconies. Aris Oikonomou / AFP
Tourists queue as they wait to take a picture from one of the balconies. Aris Oikonomou / AFP
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Greece's 'Instagram Island' Santorini nears Saturation Point

Tourists queue as they wait to take a picture from one of the balconies. Aris Oikonomou / AFP
Tourists queue as they wait to take a picture from one of the balconies. Aris Oikonomou / AFP

One of the most enduring images of Greece's summer travel brand is the world-famous sunset on Santorini Island, framed by sea-blue church domes on a jagged cliff high above a volcanic caldera.
This scene has inspired millions of fridge magnets, posters, and souvenirs -- and now the queue to reach the viewing spot in the clifftop village of Oia can take more than 20 minutes, said AFP.
Santorini is a key stopover of the Greek cruise experience. But with parts of the island nearing saturation, officials are considering restrictions.
Of the record 32.7 million people who visited Greece last year, around 3.4 million, or one in 10, went to the island of just 15,500 residents.
"We need to set limits if we don't want to sink under overtourism," Santorini mayor Nikos Zorzos told AFP.
"There must not be a single extra bed... whether in the large hotels or Airbnb rentals."
As the sun set behind the horizon in Oia, thousands raised their phones to the sky to capture the moment, followed by scattered applause.
For canny entrepreneurs, the Cycladic island's famous sunset can be a cash cow.
One company advertised more than 50 "flying dresses", which have long flowing trains, for up to 370 euros ($401), on posters around Oia for anyone who wishes to "feel like a Greek goddess" or spruce up selfies.
'Respect Oia'
But elsewhere in Oia's narrow streets, residents have put up signs urging visitors to respect their home.
"RESPECT... It's your holiday... but it's our home," read a purple sign from the Save Oia group.
Shaped by a volcanic eruption 3,600 years ago, Santorini's landscape is "unique", the mayor said, and "should not be harmed by new infrastructure".
Around a fifth of the island is currently occupied by buildings.
At the edge of the cliff, a myriad of swimming pools and jacuzzis highlight Santorini is also a pricey destination.
In 2023, 800 cruise ships brought some 1.3 million passengers, according to the Hellenic Ports Association.
Cruise ships "do a lot of harm to the island", said Chantal Metakides, a Belgian resident of Santorini for 26 years.
"When there are eight or nine ships pumping out smoke, you can see the layer of pollution in the caldera," she said.
Cruise ship limits
In June, Prime Minister Kyriakos Mitsotakis floated the possibility of capping cruise ship arrivals to Greece's most popular islands.
"I think we'll do it next year," he told Bloomberg, noting that Santorini and tourist magnet Mykonos "are clearly suffering".
"There are people spending a lot of money to be on Santorini and they don’t want the island to be swamped," said the pro-business conservative leader, who was re-elected to a second four-year term last year.
In an AFP interview, Tourism Minister Olga Kefalogianni echoed this sentiment and said: "We must set quotas because it's impossible for an island such as Santorini... to have five cruise ships arriving at the same time."
Local officials have set a limit of 8,000 cruise boat passengers per day from next year.
But not all local operators agree.
Antonis Pagonis, head of Santorini's hoteliers association, believes better visitor flow management is part of the solution.
"It is not possible to have (on) a Monday, for example, 20 to 25,000 guests from the cruise ships, and the next day zero," he said.
Pagonis also argued that most of the congestion only affects parts of the island like the capital, Fira.
In the south of the island, the volcanic sand beaches are less crowded, even though it is high season in July.
'I'm in Türkiye
The modern tourism industry has also changed visitor behavior.
"I listened (to) people making a FaceTime call with the family, saying 'I'm in Türkiye," smiled tourist guide Kostas Sakavaras.
"They think that the church over there is a mosque because yesterday they were in Türkiye."
The veteran guide said the average tourist coming to the island has changed.
"Instagram has defined the way people choose the places to visit," he said, explaining everybody wants the perfect Instagram photo to confirm their expectations.