Transit Visibility Zones of the Solar System Planets

TL;DR

This paper analyzes the regions in the sky where Solar System planets can be observed via transits, estimating detection probabilities for external observers and identifying known exoplanets with favorable viewing geometries.

Contribution

It provides a comprehensive analysis of Solar System transit visibility zones and estimates the number of potentially observable exoplanets from these regions.

Findings

Maximum of three Solar System planets can be observed simultaneously from a given point.

Probability of an external observer detecting at least one Solar System planet transit is 2.518%.

Identifies 68 known exoplanets with favorable transit viewing geometries.

Abstract

The detection of thousands of extrasolar planets by the transit method naturally raises the question of whether potential extrasolar observers could detect the transits of the Solar System planets. We present a comprehensive analysis of the regions in the sky from where transit events of the Solar System planets can be detected. We specify how many different Solar System planets can be observed from any given point in the sky, and find the maximum number to be three. We report the probabilities of a randomly positioned external observer to be able to observe single and multiple Solar System planet transits; specifically, we find a probability of 2.518% to be able to observe at least one transiting planet, 0.229% for at least two transiting planets, and 0.027% for three transiting planets. We identify 68 known exoplanets that have a favourable geometric perspective to allow transit detections in the Solar System and we show how the ongoing K2 mission will extend this list. We use occurrence rates of exoplanets to estimate that there are $3.2\pm1.2$ and $6.6^{+1.3}_{-0.8}$ temperate Earth-sized planets orbiting GK and M dwarf stars brighter than $V=13$ and $V=16$ respectively, that are located in the Earth's transit zone.