![]() When did you discover your whole life was a lie? Tell us in the comments below. If they give you a knowing nod, congratulations, you’re talking to another member of the vast chronology conspiracy. And then ask if they’d like you to incorporate the Earth’s precession, tidal locking and recent earthquakes into the calculation. So, if someone asks you how long a day is, make sure they clarify whether it’s a solar day or a sidereal day. Even as the glaciers melt, the rotation speed slows down a little more. ![]() Powerful earthquakes can change the Earth’s rotation time by a few microseconds depending on how the tectonic plates shove around. Because of our tidal interactions with the Moon, the length of a day on Earth has increased by about 1.7 milliseconds over the last 100 years. There are other events that can increase or decrease the length of an Earth day. This means that a sidereal day is actually 0.0084 seconds shorter when you account for this extra movement of the Earth’s axis. But we’re wobbling like a top, and where the axis is pointing is slowly precessing westward over the course of 26,000 years. The axis of the Earth’s pole, the imaginary line that you could draw between the south pole and the north pole is currently pointed roughly at Polaris, aka The North Star. ![]() There’s a deeper conspiracy that you’re not a part of. Aren’t you? Well, I’m here to tell you that you’re wrong too. You’re the only one who can read the signs and know the terrifying truth. You already knew that a sidereal day is a little shorter than a solar day, and that everyone else has been living a lie. But pedants among you already knew that, didn’t you? Credit: NASA / MysidĬan you imagine teaching your children how to read a clock, and then getting them to multiply that by the calendar to figure out when My Little Pony: Friendship is Magic starts? Madness.īetter to keep them in the dark, teach them that a day is 24 hours, and deny all knowledge when they get a little older, and start to ask you challenging questions. There would be no connection between what time it is, and whether or not the Sun is in the sky. For half of the year, the Sun would be up between 12am and 12pm, and for the other half, it would be between 12pm and 12am. If we only measured sidereal days, the position of the Sun would slip back, day after day. At the same time, the Earth is spinning on its axis.Įach day that goes by, the Earth needs to turn a little further for the Sun to return to the same place in the sky.… And that extra time is about 4 minutes. Why are these two numbers different? Imagine the Earth orbiting the Sun, taking a full 365 days, 5 hours, 48 minutes and 46 seconds to complete the entire journey. This is different from the amount of time it takes for the Earth to turn once on its axis – the 23 hours, 56 minutes. ![]()
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