Jeffrey Andrews-Hanna

You can see these lines propagating through the models where all of his contour lines are deflected downward.

Those are faults.

His model is predicting faults to form and to cut all the way down to the crust-mantle interface, just like we see in the gravity data here and just like Kuiper and Hartmann predicted 55 years ago.

So another thing that they talked about was these dark volcanic deposits.

We can now see these much more clearly.

And indeed, they do look very much like volcanic eruptions ponded within these rings.

And then we can look in the gravity data.

And here I'm showing the gravity gradients.

And if I go back and forth, where we see that dark deposit, we also see gravity gradient anomalies.

And in fact, they continue around and go all the way around the basin in this sort of bullseye pattern.

When we analyze profiles of these gravity gradients, we see that they match what we'd expect for a ring dike, for dense igneous rock intruded into that fault.

So again, what they were interpreting based on these images, we're now seeing very clearly in the gravity data and able to confirm.

So, Orient Hall is one of many basins, and we're looking at other impact basins.

This is a set of basins on the moon, Orient Hall, Crisium, Nectaris, Smithy.

Some of these basins are showing similar things, and we've made really great strides in trying to understand the formation of these multi-ring basins based on this gravity data.

Some of these basins are actually showing different things, so we don't yet have the whole story.

Some basins show structures very unlike what we see at Orient Hall, so there's still a lot of work left to be done

to understand this process of giant impacts on the moon.

Now, speaking of giant impacts,

There's one region on the moon where the largest impact has been proposed to occur.