I’m massively looking forward to a new BBC series, due out next year, called ‘23 Degrees’, which monitors the extremes of Earth’s weather over the year-long orbit of the planet around the Sun. The ‘23 Degrees’ bit comes from the Earth’s current tilt of about 23.4° on its axis which gives the northern and southern hemispheres their seasons, depending on their position in relation to the Sun.
In one of the regular blog posts on the upcoming series, producer Steve Marsh describes how the study of corals has shown that the Earth once spun much faster than it does today. As corals lay down daily growth rings of limestone, you can count a modern coral’s 365 daily rings over an annual cycle. But the daily rings of ancient corals dated to 400 million years ago are narrower and each annual cycle produces 410, not 365. The Earths’ orbit around the Sun has always been constant at one year, so when these ancient corals were alive the days were shorter, lasting 21 hours, meaning that the Earth was spinning faster. Around 4 billion years ago, when the Earth was relatively newly formed, a day lasted just 6 hours; the planet was spinning 4 times faster than it does today.
What if the Earth still spun this fast? As well as much shorter days and nights, here are some other changes that you might see:
1. The Earth would change shape. The Earth is not a perfect sphere, it is slightly flatter at the poles and bulges slightly at the Equator. A much faster rotation would make this equatorial bulge much more pronounced, adding thousands more miles of surface around the equatorial zone. The Earth would look more oblate, like a squashed ball.
2. Such a fast spin would put massive stress on the Earth and its crust. It would cause more regular and violent earthquakes and volcanic eruptions, and could give rise to much more pronounced geological features such as vast mountain ranges and deeper rifts, canyons and ocean trenches.
3. With the Earth’s crust under such stress, the drift of the continents would speed up and radically alter the layout of landmasses as we know them.
4. The Earth’s oceans would be much deeper in the equatorial regions and much shallower in the polar regions.
5. The Earth’s atmosphere would also be more concentrated in the equatorial regions, drastically altering the climate and weather patterns.
6. With the atmosphere rotating at the same speed as the Earth, global winds would be much more energetic. Enormous hurricanes may last for months and there would probably be a constant howling wind across the planet.
7. You may lose ‘weight’, particularly if you were stood at the Equator, through a reduction in the Earth’s gravity from the increased centrifugal force.
8. Earth may have it’s own rings, like Saturn. Saturn spins incredibly fast, with a day lasting under 11 hours. Whether the existence of it’s rings (which are mainly made from ice particles) is connected to it’s rotation speed is still a mystery. If Earth had it’s own ring system it would certainly make a spectacular sight in the sky; however, it’s shadow on the face of the planet during the short daylight hours would greatly cool those areas in it’s path.
9. If there was no ring system in the way, the Moon may be much closer to the Earth, producing an equally spectacular sight in the night sky. The Moon is actually currently moving away from the Earth, and the Earth’s spin is slowing down as a result. The effect of the Moon’s such close proximity would be seen most clearly on the Earth’s oceans, with huge waves generated with each tide.
10. Life would not have evolved in the same way. Violent earthquakes and volcanic eruptions, constant gale force winds, huge tidal waves – what intelligent life could evolve and build civilisations in conditions like these? All flora and fauna would be affected. What type of tall tree could withstand such a daily battering by the wind? Small burrowing animals, rather than apes, may reign supreme.
A faster spinning Earth would be a very alien world to us – and so it was, once.