Digital Media · Earthly/Geo/Astro · Photographics · Special · Technology

Lutetia may have witnessed the birth of the Earth


DISCOVER: When we look at the solar system now, we see it after it’s had billions of years of evolution under its belt. Things have changed a lot since it first formed out a swirling disk of material, 4.5 billion years ago. We can make some pretty good guesses about the way things looked back then, though. We can see other systems forming around other stars, for example, to get an idea of what things look like when they’re young.

But we can also look at our own solar system, look at the planets, the comets, the asteroids, and, like astronomical archaeologists, get a glimpse into our own cosmic past.

We know that asteroids formed along with the rest of the system back then. We also know that there are many kinds of asteroids: rocky, metallic, chondritic, some even have ice on or near their surface. Some formed far out in the solar system, and some formed near in. The thing is, we think the vast majority of the asteroids that formed close to the Sun were absorbed by — and by that, I mean smacked into and became part of — the inner planets, including Earth. Only a handful of those asteroids still remain intact after all this time. But now we think we’ve found one: the main belt, 130 km-long asteroid Lutetia.

Lutetia up close and personal

On July 10, 2010, the European Space Agency probe Rosetta passed just 3162 km (1960 miles) from the asteroid Lutetia, a lumpy rock 130 km (81 miles) end-to-end.

This image, taken at closest approach, shows how battered and worn Lutetia is. Craters pockmark the surface, including several that are many kilometers across. Like the Martian moon Phobos, grooves line the surface, which may be from boulders rolling around, perhaps ejected from some of the craters when they were formed. They may alternatively be stress fractures from impacts; there is still a lively debate over what causes these features in small bodies.

Much of the surface appears smooth, indicating great age for this object. Over billions of years it’s been assaulted by dust grains moving at incredible speeds, as well as the solar wind. This has essentially sandblasted the surface, taking – literally – the edge off of the rims of craters.

We have very few high-resolution images of asteroids, and the more we get, the more we learn about them. Given that every now and again we get hit by them, I’m a big fan of understanding them better. Continue HERE

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