# Reconciling the dawn-dusk asymmetry in Mercury's exosphere with the micrometeoroid impact directionality

## TL;DR

This study uses advanced dust dynamical models to explain the dawn-dusk asymmetry in Mercury's exosphere, linking it to seasonal variations in meteoroid impacts driven by cometary dust sources.

## Contribution

The paper introduces new dynamical models calibrated with recent measurements, revealing how seasonal dust flux variations cause the observed exospheric asymmetry on Mercury.

## Key findings

- Dawn-dusk asymmetry in Mercury's exosphere is linked to meteoroid impact patterns.
- Impact vaporization sources shift towards the nightside near aphelion.
- Sources move towards the dayside as Mercury approaches the Sun.

## Abstract

Combining dynamical models of dust from Jupiter Family Comets and Halley-type Comets, we demonstrate that the seasonal variation of the dust/meteoroid environment at Mercury is responsible for producing the dawn-dusk asymmetry in Mercury's exosphere observed by the MESSENGER spacecraft. Our latest models, calibrated recently from ground-based and space-borne measurements, provide unprecedented statistics that enable us to study the longitudinal and latitudinal distribution of meteoroids impacting Mercury's surface. We predict that the micrometeoroid impact vaporization source is expected to undergo significant motion on Mercury's surface towards the nightside during Mercury's approach to aphelion and towards the dayside when the planet is approaching the Sun.