HD7977 Archives - Astrobiology

Panel (a)-(c) is the snapshots of the REBOUND simulation. Colors represent the angular momentum value of each comet. Those with blue colors have a possibility of entering the inner solar system. The pentagram symbol denotes the Sun, the gray trajectory represents the flyby path of HD7977, and the purple trace illustrates the orbit of the selected comet. The insets inside each plot show the magnified orbit evolutionary of a selected representative comet. Panel (d) is the distribution of angular momentum change of Inner Oort cloud comets. -- astro-ph.EP

Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Comets and Asteroids, Extinction events, Interstellar, Status Report

On The Coincidence Between The Close Passage Of HD7977 And The Pliocene-Pleistocene Transition

by Keith CowingNovember 24, 2025November 24, 2025

The Oort Cloud’s dynamical evolution is significantly influenced by both the galactic tide and stellar flybys.

Illustration of the uncertainty of Earth's orbit 56 million years ago due to a potential past passage of the Sun-like star HD7977 2.8 million years ago. Each point's distance from the center corresponds to the degree of ellipticity of Earth's orbit, and the angle corresponds to the direction pointing to Earth's perihelion, or closest approach distance to the Sun. 100 different simulations (each with a unique color) are sampled every 1,000 years for 600,000 years to construct this figure. Every simulation is consistent with the modern Solar System's conditions, and the differences in orbital predictions are primarily due to orbital chaos and the past encounter with HD 7977. Credit: N. Kaib/PSI.

Astronomy & Telescopes, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Habitable Zones, Press Release, Stellar Cartography

Stellar Cartography: Passing Stars Altered Orbital Changes For Earth And Other Planets

by Keith CowingFebruary 15, 2024February 15, 2024

Stars that pass by our Solar System have altered the long-term orbital evolution of planets, including Earth, and by extension modified our climate.