Reconstructing the photometric light curves of Earth as a planet along its history

TL;DR

This study reconstructs Earth's historical cloud cover and simulates its photometric light curves across different geological epochs, revealing increased variability in the past which aids in exoplanet characterization.

Contribution

It introduces a method to estimate historical cloud distributions and simulate Earth's photometric variability over geological time scales.

Findings

Modern Earth’s cloud distribution matches the model predictions.

Historical epochs show higher photometric variability than today.

Enhanced variability could help in detecting exoplanet features.

Abstract

By utilizing satellite-based estimations of the distribution of clouds, we have studied the Earth's large-scale cloudiness behavior according to latitude and surface types (ice, water, vegetation and desert). These empirical relationships are used here to reconstruct the possible cloud distribution of historical epochs of the Earth's history such as the Late Cretaceous (90 Ma ago), the Late Triassic (230 Ma ago), the Mississippian (340 Ma ago), and the Late Cambrian (500 Ma ago), when the landmass distributions were different from today's. With this information, we have been able to simulate the globally-integrated photometric variability of the planet at these epochs. We find that our simple model reproduces well the observed cloud distribution and albedo variability of the modern Earth. Moreover, the model suggests that the photometric variability of the Earth was probably much larger in past epochs. This enhanced photometric variability could improve the chances for the difficult determination of the rotational period and the identification of continental landmasses for a distant planets.