The Origin: From Planets to Craters

To date, we have confirmed the existence of more than 5000 extrasolar planets, which are planets orbiting stars other than the Sun. These range from gas giants that are more massive than Jupiter, down to low-mass planets that are almost certainly rocky, with internal compositions similar to that of Earth. However, these low-mass exoplanets typically orbit much closer to their parent stars than Earth does to the Sun, or orbit stars that are less massive than the Sun. We have yet to find a true Earth analogue: a ~1 Earth mass planet orbiting with a period of about 1 year around a star like the Sun. This talk summarises our current understanding of how Earth-like planets might form, what our knowledge of exoplanetary systems tells us about the likely origin of these planets, and when we might expect to detect a true Earth analogue.

There are around 200 impact craters preserved on Earth’s surface, ranging in size from a few hundred metres to hundreds of kilometres in diameter. These represent only a small fraction of the total number of impact events that have occurred over geological history, most of which are very poorly preserved. The discovery of the Nadir Crater offshore West allows us to investigate a pristine, buried crater, that provides important new insights on what a mid-sized (~500 m) asteroid impact would look like, in terms of Earth surface damage and hazards (seismic shaking, tsunami). This talk will explore the evidence for the impact event and the consequences of the event, as well as the intriguing possibility that this could represent part of a cluster of impact events near the end of the Cretaceous period.