One year on Earth could never be the same amount of time as a year on Mars, Jupiter, Saturn, or any other planet. Time can be measured in many different ways besides the number of rotations of our Earth around the Sun. The Sun itself, along with all the planets, is revolving around the galactic core, where it lies the supermassive black hole Sagittarius A. Although this latter cosmic beast can obliterate anything and anyone that gets too close, it plays a crucial role in the existence of our galaxy.
Therefore, a galactic year practically means a full rotation of the solar system around the kernel of our Milky Way galaxy. Such a journey lasts for 220 million to 230 million Earth years, according to Keith Hawkins, who is an assistant professor of astronomy at the University of Texas from Austin.
Earth is just 16 years old
Furthermore, if we measure time by the method presented above, we’ll conclude that the Earth would be only about 16 years old, the Sun would have been born about 20 years ago, and the whole Universe would be about 60 years old.
Keith Hawkins explains:
The sun is moving with enough speed — about 230 kilometers a second, about the equivalent of 500,000 miles per hour — that it continues to revolve around the center of the galaxy in sort of a circle
But Hawkins once again reminds us about the wonderful relativity of time:
We would say that a galactic year is 220, 230 million years. Other stars in the galaxy, their galactic year is different,
On the other hand, if we switch from the ‘big universe’ to the ‘small universe’, we can remind ourselves that what we humans mean by a second practically means six full rotations of an electron around the nucleus of a cesium atom. By raising the stakes, we all know that a day is practically a full rotation of the Earth around its own axis that lasts for 24 hours. Time in our physical reality is measured mechanically, although we like to admit it or not.