Joss Bland-Hawthorn

The Sagittarius galaxy plunged into the disk of the Milky Way and passed through again and again, like a stone thrown into a still pond. Each strike left ripples: waves and warps in the star field.

The stellar halo of the Milky Way is a galactic palimpsest: an ancient manuscript where earlier layers lie hidden beneath the visible text. For a long time, the Gaia-Sausage-Enceladus (GSE) structure was thought to be the final entry in this manuscript, the scar of a single catastrophic merger.

The potter’s wheel of the cosmos spins faster than we imagined. Look at galaxy UDS 12999: its light traveled 7.6 billion years, but James Webb discerned a perfectly cast X-shaped bulge already at its center. This is no mere pattern: it’s the fingerprint of a mighty stellar bar that, like a potter, stretched and molded the central region.

When we peer deep into space, we see the past. Edwin Hubble’s law turns redshift into a time machine: light from galaxy UDS 12999 traveled to us for 7.6 billion years — more than half the age of the Universe.