Uh, There's a Giant Gravity Hole in the Indian Ocean

Experts have known about it for decades but had no idea where it came from, until now

Hiya!

As technology advances, we can finally take the next step in exploring and learning about ourselves and our planet. I’ve already shared with you recent scientific gains allowing us to analyze the genome of our ancient ancestors, discover thousands of ancient ruins, and map the ocean floor. But we’re going deeper than that — literally — as experts have also found giant blobs near the center of Earth, along with two new layers.

The blobs, in particular, happen to make an appearance later on in this article because they have something to do with a massive and mysterious “hole” located in the Indian Ocean. Not only has the hole’s origin baffled experts for decades, but it also has the lowest gravity on the planet. Now, a recent study brings new answers that help explain the phenomena.

Earth is an Oddball

First, it’ll help us understand the study better if we review some basics regarding the realities of Earth. As kids, we’re taught the Earth is round like a ball, a concept supported by globes and our brain’s preference for simplicity. So we often live the rest of our days assuming Earth is a perfect sphere, and gravity is the exact same at every point on its surface.

The truth is, Earth is an oddball, with flat-ish North and South poles and bulges out around the equator. Just like Earth isn’t perfectly round, gravity isn’t evenly spread across the planet either. The mass from the planet's core, mantle, and crust are unevenly distributed beneath our feet, which means gravitational forces across the Earth’s surface also vary.

Combining the local gravity measurements from satellites and ground-based sensors shows experts what effects these gravitational tugs from the insides of the Earth would have on the ocean’s surfaces without the influence of tides or winds. The result is an exaggerated image of Earth’s high and low gravitational spots called the global geoid, such as the infamous “Potsdam gravity potato” shown below.

Image Source: European Geoscience Union. The geoid, also known as “Potsdam Gravity Potato.” Data based on satellite LAGEOS, GRACE, and GOCE and surface data, airborne gravimetry, and satellite altimetry, as well as on the long-term data series.

Remember, this is just a representation of the oceans’ surfaces if the planet’s gravitational forces came only from Earth’s rotation and its effects on the core, mantle, and crust’s masses. Excluding any influence from winds and tides.

See that light blue spot?

That’s where the ultra-low gravitational hole is. A particularly pronounced low gravitational point, or “hole,” in the global geoid under the Indian Ocean — a spot creatively known as the Indian Ocean geoid low (IOGL) — and it’s Earth’s most prominent gravitational oddity.