A Moment of Science

24 Themis: An Icy Asteroid

Learn about 24 Themis, one of the largest known asteroids.

asteroid

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The 24 Themis asteroid has frozen water on its surface

One of the most intriguing questions in science is where the earth’s oceans came from. Did the planet always have water? Or did it come from somewhere else?

Answering Questions…

A discovery suggests that Earth owes its watery nature at least in part to extraterrestrial sources. Namely, asteroids.

A team of scientists published a report showing that one of the largest known asteroids in the solar system, called 24 Themis, has frozen water on its surface.

How Much Water?

Scientists have long suspected that asteroids contain water. But until now, they’ve had to estimate how much water a given asteroid may have had by measuring the minerals found in meteorites.

In 2009, for the first time, scientists confirmed that asteroids do in fact harbor water in ice form. They used an infrared telescope to observe and take pictures of 24 Themis for seven hours as it spun in its orbit.

Icy Coating

The images revealed that the rocky object is covered entirely by an icy coating of frozen water.

The researchers suspect that the asteroid’s ice is constantly renewed by a mass of ice beneath its surface.

Why Does This Matter?

Before you say, “OK, but so what?”, consider that 24 Themis is nearly 125 miles across. That’s a lot of frozen water.

If water bearing asteroids the size of 24 Themis and even larger regularly bombarded the Earth in its early years, they very well might have supplied much of the water that makes up our oceans.

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