Ichha Sharma, Pune
Last year, the James Webb Space Telescope brought to our attention a remarkable discovery: “Maisie’s galaxy.” This cosmic find has now proven to be the earliest galaxy ever identified, giving us a glimpse of its state just 390 million years after the Big Bang.
Astronomers are thrilled by the revelations surrounding Maisie’s galaxy. Among the first distant galaxies spotted by the JWST, it’s now the first to be verified through spectroscopy, an exciting confirmation. The individual behind the discovery, Steven Finkelstein, an astronomy professor at UT Austin, even named the galaxy after his daughter, Maisie, since it was stumbled upon on her birthday.
The fascinating twist in observing distant celestial entities is that what we see is their state at the moment the light left them. For instance, when we gaze upon a galaxy situated a million light-years away, we’re essentially peering into its past, as it was a million years ago.
However, these cosmic messengers don’t include a timestamp with their light. To decipher when the light originated, scientists analyse the “redshift—the shift in an object’s colors due to its motion away from us. Given the universe’s expansion, objects farther away are in motion away from us, leading to higher redshifts when looking further back in time.
Initially, the estimated redshift of Maisie’s galaxy relied on photometry, gauging light brightness through wide-frequency filters in images.
To pinpoint its age more accurately, the CEERS (Cosmic Evolution Early Release Science Survey) team pursued additional measurements using Webb’s NIRSpec instrument. This tool dissects an object’s light into numerous narrow frequencies, offering insights into its chemical composition, heat emissions, inherent brightness, and relative movement.
In essence, this discovery, named after a special moment, holds the key to unraveling the universe’s early days and how galaxies like Maisie’s shaped the cosmos we know today.