A light-year is the distance light travels in one year, about 9.46 trillion kilometers. It is a unit of distance, not time, and it lets astronomers express the vast gulfs between stars in manageable numbers. The nearest star to the Sun, Proxima Centauri, lies 4.24 light-years away. Because light takes time to reach us, looking far out in space is also looking back in time: we see the most distant galaxies as they were billions of years ago.
Cosmology · Exoplanets · Direct Imaging
Almost every planet we have imaged directly is a young, glowing furnace. Then JWST captured a mature, frigid super-Jupiter twelve light-years away, ne...
Cosmology · Search for Life · Technosignatures
An advanced civilization might betray itself not with a message but with its machinery: the waste heat of a star wrapped in solar panels, a chemical s...
Astrophysics · Milky Way · Galactic Center
In 2010, a space telescope revealed two colossal balloons of energy tens of thousands of light-years above and below the center of our galaxy, the sca...
Astrophysics · Solar System · Comets
Far beyond Pluto and the Kuiper Belt, the solar system may end in a vast spherical cloud of icy bodies reaching nearly a light-year out. We have never...
Cosmology · Exoplanets · Magma Worlds
Thirty-five light-years away, the super-Earth L 98-59 d has no solid ground. A permanent ocean of magma feeds a sky laced with sulfur, and it may be t...
Astrophysics · Supernovae · Black Holes
A star 730 million light-years away brightened for four years, exploded, then exploded again. No human flagged it. An algorithm built to find the stra...