在古代，按公历来说，元旦不仅仅是⼀⽉⼀号这⼀天。元旦的⽇期从殷朝腊⽉初⼀改到汉朝的正⽉初⼀。公元1911年，孙中⼭领导的⾟亥⾰命，推翻了满清的统治，建⽴了中华民国。各省都督代表在南京开会，决定使⽤公历，把农历的正⽉初⼀叫做“春节”，把公历的1⽉1⽇叫做“元旦”。
元旦的由来英⽂：
Legend in 4000 years ago, when the ancient yao and shun sheng shi, yao tianzi in office diligent for the people do a lot of good things, by the majority of the people love, but because his son no talent is not too good, he did not pass the "son of heaven" to his son, but to the character and ability of shun. Yao said to shun。
"you must hand over the throne to the emperor from now on. Later, shun passed the throne to yu, who did a good job in flood control. Like shun, yu loved the people and did many good deeds for the people. Later people yao died, shun emperor worship heaven and earth and first emperor yao that day, as the beginning of the year, the first day of the first month known as "New Year's day", or "yuan zheng", this is the ancient New Year's day.
以下是我的回答，元旦的由来英文版简短50字如下：
New Year's Day is a time for celebration, reflection, and the renewal of promises to oneself.
