Jupiter - friend or foe? II: the Centaurs

TL;DR

This study investigates how Jupiter influences impact risks from Centaur objects, revealing that Jupiter can increase the impact flux on Earth rather than reduce it, challenging the traditional view of Jupiter as a protective shield.

Contribution

It provides new insights into the impact regime of Centaurs and demonstrates that giant planets can sometimes increase impact risks rather than decrease them.

Findings

Giant planets can significantly alter impact rates from Centaurs.

Presence of a giant planet often increases impact flux on Earth.

Jupiter may act as a contributor to impact risk, not just a shield.

Abstract

It has long been assumed that the planet Jupiter acts as a giant shield, significantly lowering the impact rate of minor bodies upon the Earth, and thus enabling the development and evolution of life in a collisional environment which is not overly hostile. However, in the past, little work has been carried out to examine the validity of this idea. In the second of a series of papers, we examine the degree to which the impact risk resulting from objects on Centaur-like orbits is affected by the presence of a giant planet, in a continuing attempt to fully understand the impact regime under which life on Earth has developed. The Centaurs, which occupy orbits beyond Jupiter, have their origins in the Edgeworth-Kuiper belt that extends beyond Neptune. The giant planets peturb the Centaurs, sending a significanr fraction into the inner Solar System where they become visible as short-period comets. In this work we present results which show that the presence of a giant planet can act to significantly change the impact rate of short-period comets on the Earth, and that a giant planet often actually increases the impact flux greatly over that which would be expected were it not present. (Shortened version of abstract.)