Eärendel: The Earliest and Most Distant Star Known

In a remarkable discovery, astronomers have identified the earliest and most distant star ever observed: Eärendel. This cosmic marvel was detected in 2022 using the powerful capabilities of the Hubble Space Telescope.

A Glimpse into the Early Universe

Eärendel is located at a comoving distance of 28 billion light-years (8.6 billion parsecs). This astonishing distance places it in the very early stages of the universe's history. The light we are now seeing from Eärendel traveled for approximately 12.9 billion light-years to reach us.

The Magic of Gravitational Lensing

Observing objects at such immense cosmological distances is a monumental challenge. However, stars like Eärendel can be studied thanks to a phenomenon known as gravitational lensing. Massive objects, such as galaxy clusters, can bend and magnify the light from more distant objects behind them. In the case of Eärendel, the magnification factors can exceed an incredible 1,000, making this ancient starlight visible to our telescopes.

Understanding the Distance and Age Paradox

A common question arises: how can a star be 28 billion light-years away when the estimated age of the universe is only 13.79 billion years? The answer lies in the expansion of spacetime itself.

While the light from Eärendel took 12.9 billion years to reach us, the universe has been expanding throughout that time. This continuous expansion means that the initial distance between us and Eärendel when the light was emitted has increased significantly. Therefore, Eärendel's current comoving distance is 28 billion light-years, even though the light has only been traveling for a fraction of the universe's age.

A Name Fit for a Star

The name Eärendel itself has a rich connection to mythology. It's a name familiar to fans of J.R.R. Tolkien's works, appearing in "The Silmarillion" and other Middle-earth stories. Eärendil was a legendary mariner who carried a powerful gem, the Silmaril, across the sky, representing the morning star. Tolkien himself drew the name from an Old English poem where Eärendel is referred to as "The Brightest of Angels." This fittingly celestial moniker underscores the profound significance of this distant stellar discovery.

Credit: NASA, ESA, CSA, D. Coe (AURA/STScI for ESA), Z. Levay