Dwarf planet 2023 KQ14, Ammonite, has a stable orbit that challenges the hypothesis of the mysterious Planet Nine.

The methane gas may constitute a rarefied atmosphere, or it may come from erupting plumes on Makemake’s surface.

The interstellar object hurtling toward the inner solar system, where Earth is located, is much larger than previously thought, astronomers say.

This invisible boundary is known as the heliosphere. It's the endpoint beyond which our Sun does not have any reach or power.

Object 3I/ATLAS is now too far from Earth to aim a telescope at, but prior observations showed some unusual behavior. The anomalous nature of the object led astrophysicist Avi Loeb to apply a thought ...

The outer solar system is a vast and mysterious place that could be harboring hidden objects we know almost nothing about — from the elusive Planet Nine and baby black holes to interstellar visitors ...

A tiny meteorite is rewriting what scientists thought they knew about the origins of our solar system. New evidence found in shavings from a meteorite known as Northwest Africa 12264 — a 50-gram (1.8 ...