All over the globe people are preparing to jump into the new year. But what does it mean to ‘enter a new year’?
For some it might feel like a repetition of last year. And the year before that. And the year before that. We get ready to start a new year, where we will try to do better than the year that has just past.
A new year starts when Earth has made one orbit around the Sun. This takes roughly 365 days, so every new year on the last day of December, we are at the same location around the Sun as last year. This also goes for any other day during the year.
There is no astronomical reason for having New Years on December 31st – it is just how we constructed our calendar system. (Which by the way was invented by ourselves. The 12 month calendar is not a Universal given.)
New Years Is Just The Same As Last Year – Or Is It?
The Sun is just one of 200 billion stars in our galaxy, which is called the Milky Way. All these stars are distributed in an enormous spiral. The Sun (and hence the Solar System and us here on Earth) is located in one of these spiral arms.
All the stars in the Milky Way are orbiting the center. Just like water spiraling out the drain of a bathtub the stars spiral around the central black hole. Depending on the location of the star, i.e. how far it is from the center, the orbit speed can be high or low.
For the Sun it takes around 250 million years to orbit once around the Milky Way. This means that in 250 million years we will be back at the same location in the Galaxy as we are today.
So when you jump into a new year on Dec 31st and think that you have done this before many times, you are mistaken. It is the first time you are starting a new year at this location in the Galaxy.
A new year might start with another round in the same orbit around the Sun – but it is a new place in the galaxy. And unless you live to be 250 million years old, you will not have done this before.