Peering into the distant reaches of the cosmos, the Hubble Space Telescope has captured an image of a galaxy that is a ghostly, hazy mirror of our own Milky Way. Residing a staggering 44 million light-years away in the constellation Pavo, NGC 6684 is a lenticular galaxy, a term coined for its lens-like appearance when viewed side-on. This remarkable discovery was made coincidentally during Hubble’s ongoing census of galaxies within 32.6 million light-years, a daunting task that it is about three-quarters of the way through.
Unlike the Milky Way’s classic spiral structure, with its rotating disk of spiral arms full of stars interspersed with dark lanes of dust and empty space, NGC 6684 houses a bulge of stars at its core surrounded by a disk of stars, but devoid of spiral arms. Lenticular galaxies like NGC 6684 are known to harbor older stars than spiral galaxies, leading astronomers to speculate that these galaxies could be aging spiral galaxies whose arms have faded, or spirals that have merged. Intriguingly, recent evidence suggests that our own Milky Way may have once been a lenticular galaxy billions of years ago, before a series of galactic collisions shaped its current spiral form.
A Glimpse into the Distant Universe: NGC 6684
The Unearthly Beauty of Lenticular Galaxies
The Hubble Space Telescope, in its mission to capture images of galaxies within 32.6 million light-years of Earth, has stumbled upon an intriguing find 44 million light-years away. The galaxy, named NGC 6684, is a lenticular galaxy, a type characterized by a hazy, ghostly shape that resembles a lens when viewed side-on.
Lenticular galaxies, as NASA explains, are strikingly different from our own Milky Way, which is a classic spiral galaxy. While the Milky Way features a rotating disk of stars forming spiral arms with dark lanes of dust and empty space in between, lenticular galaxies like NGC 6684 possess a disk of stars without any spiral arms but hold a bulge of stars at their core.
A Journey Through Galactic Evolution
NGC 6684 is not only an exemplar of the lenticular galaxy type but also a testament to the cosmic evolution. Lenticular galaxies are thought to contain older stars than their spiral counterparts, leading astronomers to believe that they could be aging spiral galaxies whose arms have faded or merged. This theory is backed by recent evidence suggesting that our Milky Way might have been a lenticular galaxy billions of years ago, before a series of galactic collisions gave it its signature spiral arms. Other lenticular galaxies recently imaged by Hubble include NGC 1023, NGC 5283, and NGC 3489.
Observing the Celestial Skies
While NGC 6684 is far too distant to be viewed with backyard telescopes or binoculars, there is a galaxy that skywatchers can easily observe. In late September and early October, the Andromeda galaxy, also known as M31, becomes visible in the eastern sky. As the closest major galaxy to the Milky Way, Andromeda appears to the naked eye in very dark skies as a whitish nebulous cloud. It is located near the Andromeda and Cassiopeia constellations and is also visible through stargazing binoculars from almost anywhere.
A Galactic Collision in the Making
For the very best view of Andromeda, however, astronomers suggest waiting another 4 billion years. That’s when Andromeda is estimated to collide with the Milky Way, merging the two galaxies into one.
The discovery of NGC 6684 and the understanding of lenticular galaxies provide a fascinating insight into the processes of galactic evolution. It serves as a reminder of the vast and dynamic universe we are a part of. As we continue to gaze at the night sky, we are not just spectators but active participants in a cosmic narrative that extends billions of years into the past and the future.