The Firefly Sparkle galaxy observed with JWST (left) reveals ten bursty star clusters stretched and magnified by gravitational lensing. The reconstruction of the original galaxy (middle) is made possible by the creation of a map for the foreground lens, revealing a precursor galaxy that’s analogous to a modern Milky Way-like galaxy (right). (Credits: NASA, ESA, CSA, STScI, Chris Willott (NRC-Canada), Lamiya Mowla (Wellesley College), Kartheik Iyer (Columbia) (left); NASA, ESA, CSA, Ralf Crawford (STScI) (mid); ESA/Hubble & NASA (right))
The Firefly Sparkle galaxy was only spotted because of gravitational lensing’s effects. Yet galaxies like these brought us a visible cosmos.
How did our Universe become the way it is today?
A portion of the dwarf galaxy Wolf–Lundmark–Melotte (WLM) captured by the James Webb Space Telescope’s Near-Infrared Camera. This region showcases some of the stars located within WLM, some ~3 million light-years away, along with many background galaxies of various sizes and distances. The Universe, even when we look within a nearby galaxy, can’t help but reveal itself when we look with JWST’s eyes. (Credit: NASA, ESA, CSA, Kristen McQuinn (RU); Image processing: Zolt G. Levay (STScI))
Nearby, modern galaxies only give us a single snapshot.
This view of the Perseus cluster of galaxies, from ESA’s Euclid mission, shows over 1000 galaxies all clustered together some 240 million light-years away, with many tens of thousands more identifiable in the background portion of the image. While optically, the image is dominated by the most massive, star-rich galaxies, they are vastly outnumbered by smaller, fainter, low-mass galaxies that are exceedingly difficult to detect, even nearby. Euclid’s capabilities are critical for mapping out the dark Universe. (Credit: ESA/Euclid/Euclid Consortium/NASA, image processing by J.-C. Cuillandre (CEA Paris-Saclay), G. Anselmi, CC BY-SA 3.0 IGO)
To understand cosmic history, we must look far away: back in time.
This selection of 55 galaxies from the JWST’s GLASS Early Release Science program span a variety of ranges in redshift and mass. This helps teach us what shapes galaxies take on over a range of masses and stages in cosmic time/evolution, revealing a number of very massive, very early, yet very evolved-looking galaxies. If we can see them now, they’ll always be visible, a contrast to the myth of the disappearing Universe. (Credit: C. Jacobs, K. Glazebrook et al., arXiv:2208.06516, 2022)
JWST has shown us the earliest galaxies ever discovered.
Even from this zoomed-in view of the JADES field, it’s very difficult to pick out the most distant galaxy ever found, JADES-GS-z14–0, by eye. This animation shows its location with a green circle: overlapping with a brighter, bluer, closer galaxy. (Credit: NASA, ESA, CSA, STScI, B. Robertson (UC Santa Cruz), B. Johnson (CfA), S. Tacchella (Cambridge), P. Cargile (CfA); Animation: E. Siegel)
But there’s a problem: it can only see the brightest ones.
