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.



Fans Bid Farewell to 4 Giant Pandas at Japan Zoo Before their Return to China

Giant panda Saihin, one among the four pandas on loan to Japan which will soon be heading back to China sits inside an enclosure at Adventure World in Shirahama, Wakayama Prefecture, Japan, Friday, June 27, 2025. (AP Photo/Ayaka McGill)
Giant panda Saihin, one among the four pandas on loan to Japan which will soon be heading back to China sits inside an enclosure at Adventure World in Shirahama, Wakayama Prefecture, Japan, Friday, June 27, 2025. (AP Photo/Ayaka McGill)
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Fans Bid Farewell to 4 Giant Pandas at Japan Zoo Before their Return to China

Giant panda Saihin, one among the four pandas on loan to Japan which will soon be heading back to China sits inside an enclosure at Adventure World in Shirahama, Wakayama Prefecture, Japan, Friday, June 27, 2025. (AP Photo/Ayaka McGill)
Giant panda Saihin, one among the four pandas on loan to Japan which will soon be heading back to China sits inside an enclosure at Adventure World in Shirahama, Wakayama Prefecture, Japan, Friday, June 27, 2025. (AP Photo/Ayaka McGill)

Thousands of fans bid a teary farewell Friday to a family of four giant pandas at a zoo in Japan’s coastal town of Shirahama as the animals made their last public appearance before their return to China.

Around 3,000 visitors flocked to the Adventure World theme park to get a last glimpse of the beloved animals. Many rushed straight to the panda exhibit zone, calling out the names of their favorites, The Associated Press reported.

Although the 24-year-old mother Rauhin and her three daughters — Yuihin, Saihin and Fuhin — were all born and raised at the park, they remain on loan from China and must now be returned.

Once they return to China, Xiao Xiao and Lei Lei at Tokyo’s Ueno Zoo will be the only pandas left in Japan.

More than 1,000 people, many wearing panda-themed attire, queued outside the entrance of the theme park hours before it opened while some camped outside the night before.

Some people wiped off tears while viewing throwback images of the pandas when they were cubs.

Yoshihiko Fukuzumi recalls the arrival of the first two pandas at the park 30 years ago and has watch their family grow. Since retiring three years ago, he and his wife have visited them nearly everyweek. “To us, they are like our grandchildren."

Giant pandas are native to southwestern China and serve as an unofficial national mascot. Beijing lends them to other countries as a sign of goodwill but maintains ownership over them and any cubs they produce.

Born in 2000, Rauhin had seven other cubs with Eimei, a male panda sent from China in 1994. Eimei returned home two years ago and has since died.

Despite strained political ties between Japan and China, giant pandas are hugely popular in Japan.

“We feel comforted just by looking at pandas,” said zoo director Koji Imazu.

Imazu said the departure of the four pandas marks the end of the zoo's 30-year joint project with China. He thanked Chinese specialists for sharing their expertise with the Japanese staff and said the zoo will be ready for a new arrival at any time.

“Of course we all miss them, but I hope you could send them off with a cheerful wave and wish them well in China,” Imazu said.

In Beijing, China's Foreign Ministry spokesperson Guo Jiakun said giant pandas are “friendly ambassadors" conveying the goodwill of the Chinese people.

Guo said that China and Japan have collaborated on panda conservation and research since 2000, and that China is ready to further strengthen international cooperation, including with Japan.

Rauhin and her daughters will be flown to China on Saturday where they will join other pandas at a facility in Sichuan province near their original habitat. There, the three young ones will find partners.

“I still can't believe they're all leaving,” said Junko Ikeda, a Fuhin fan from neighboring Nara prefecture who spent Thursday night in her camper van for the send-off. "I hope she finds a partner, becomes a mother and lives a happy life.”