Earth Day

Celebrated at the end of every Ymir Year, Earth Day celebrates the time when humanity first set foot on planet Ymir. This took place ████████ after the Starseed vessel first arrived in orbit. During Earth Day, the population receives Holiday Rations and most have a day off. Those at work have their wages doubled by the government, a bonus that is excluded from taxation.
Earth Day celebrations focus on both the departure from Earth, and the first step taken on an alien planet. It's the closest thing to New Year's Eve that Ymir society knows, because even scientists can only approximate what date it would be on Earth. The loss of time connection with Earth has upset people more than anticipated, which makes this day of celebration also a day of grief for many Earthborn. For Ymirborn it is merely a day of celebration.
To celebrate, people will cook old Earth recipes and listen to music from Earth. The Science Department is rumoured to celebrate by listening to messages sent from Earth, and sending their updates back. However, it is said that due to the technical nature, they do not share these messages with the public. Some claim it really is to make sure that if Earth ceases contacting Ymir, the population will not have an existential crisis.

Ymir Years

Because Ymir is tidally locked, so no day-night cycle, and has an orbital period of a mere 32 days, there is no proper way to tell time or even years. As such, an artificial calendar was created, which are called Ymir Years. These have approximately the same length as Earth Years. Under the current design, it would take 1875 Ymir Years on average to end up approximately 1 day off the Gregorian Calendar.
Seconds are the same length, but Ymir Days are 25 hours, to better fit human biological cycles. A year consists of 10 months of 35 days, so every year starts on a Monday. 2 out of every 3 years have a weekless leapday, which is when Earth Day is celebrated. When a year has no leapday, the last sunday becomes Earth Day. Every 30 years the 29th year also has no leapday.
Due to time dilation, it is impossible to know for sure what date it is on Earth. As such, the choice was made to just start the year on the day of first landing. Other relevant dates that were considered, were the day of arrival, day of first Awakening, and the day that drones landed to help clear a landing site. However, those were all judged to be of less emotional value.

Date

Leap Day (leap years)
Last Sunday of year (non-leap years)

Celebrated Since

End of first Ymir Year

Festivities Duration

All day

Acknowledgement

Society-wide

Government Status

Official Holiday

---

Government gift

2x Holiday Rations

Work status

Untaxed double compensation