005: Time
Our way of telling time is solely based on our situation here on the Earth. But what if we lived on a habitable exoplanet where our ideal methods of telling time don’t work?
Our closest star is Proxima Centauri. It’s now confirmed that there is a reasonably Earth-like exoplanet, 1.17 times the mass of Earth, around it called Proxima b. That would make it the closest exoplanet in the galaxy. Given that it’s 20 times closer to its red dwarf sun, than the distance from the Earth to the Sun, there is a high probability that this planet is tidally locked.¹ Such a configuration could support life, but it would be catastrophic to our concept of the calendar.
Tidally locked means that it moves in the same fashion as the Moon. The same side of the Moon is always facing the Earth. As such, if you stood on the surface of the sun facing side of Proxima b, the sun would be stationary in the sky. If the sun never moves in the sky, how do you know the hour of the day? If the sun never rises or sets how do you know what day it is?
It seems unlikely that Proxima b would have a moon, given its close distance to its sun. We use our moon to determine the month. Without a moon, how do you know what month it is?
The Earth is tilted 23.5˚ relative to the Sun, creating the seasons. Proxima b is likely straight up and down relative to its sun. Thus, you will never feel the change of the seasons. Our year on Earth is determined by circumnavigating the Sun. At night, you can see the change of our position in the stars. However, if you were on Proxima b, the sunlight side sky would be perpetually opaque.
So, it would be worse than the movie “Groundhog Day.” Instead of being in the same day over and over, you would be trapped in the same hour! The moral of the story is, if you’re traveling to Proxima b, be sure to bring an expensive watch.
Reference:
Strickland, Ashley. (2020). Astronomers confirm Earth-size exoplanet around nearest star and maybe more. CNN. Retrieved from https://www.cnn.com/2020/06/04/world/proxima-b-proxima-c-exoplanets-scn/index.html.