Science & Technology

An Undiscovered Galaxy Just Photobombed the Hubble Telescope

When NASA compares a scientific discovery to a game of "Where's Waldo?", you know something fun will be announced. It turns out the Hubble Space Telescope discovered a dwarf galaxy in our stellar neighborhood. The best thing about this find is it was completely accidental.

Related Video: The Hubble Telescope Takes Some Amazing Pictures

Loner Galaxy

What the telescope was really doing was photographing a star cluster called NGC 6752, which is 13,000 light-years away — a respectable distance by cosmic standards. (A light-year is the distance light travels in a year; our own Milky Way galaxy is about 100,000 light-years across.)

So imagine astronomers' surprise when a "loner" galaxy popped up in the image. It was super-tiny and super-faint, but scrutiny showed that this tiny, 3,000-light-year-across galaxy was something like 30 million light-years away from us. That's about 12 times further than the Andromeda Galaxy, a bright object that northern hemisphere observers can see with the naked eye (no telescopes or binoculars needed).

Now that astronomers know where this galaxy is hiding, they promise us that it will teach us more about how galaxies change as they grow and age. In fact, this galaxy is almost as old as our universe itself, which is estimated at 13.7 billion years. "Because of its 13-billion-year-old age, and its isolation — which resulted in hardly any interaction with other galaxies — the dwarf is the astronomical equivalent of a living fossil from the early universe," NASA said in a statement.

This is a Hubble Space Telescope image of a concentration of stars within the globular cluster NGC 6752. Hidden among the stars is an image of a background galaxy that is much farther away. The diminutive galaxy, named by its discoverers as Bedin 1, measures only around 3,000 light-years at its greatest extent — a fraction of the size of the Milky Way. Not only is it tiny, but it is also incredibly faint. These properties led astronomers to classify it as a dwarf spheroidal galaxy that is as old as the universe.

What Can This Galaxy Tell Us?

Once we know what a galaxy looks like when it's unchanging, astronomers can make predictions about how changing galaxies grow and evolve. This will help us better understand the shape of the galaxies surrounding us, and even our own Milky Way. We do know a few things for sure, such as the fact that the Milky Way and Andromeda are on an eventual collision course in a few billion years. But let's face it — space is full of mysteries, and we're just getting started with our explorations.

Meanwhile, Hubble just keeps on observing and producing results nearly 29 years after its launch into space — an age that puts it nearly on par with the reunification of Germany and the fall of the Berlin Wall. What's more, Hubble remains in good health.

This composite image shows the location of the accidentally discovered dwarf galaxy, named by its discoverers as Bedin 1, which lies far behind the foreground globular cluster NGC 6752. The lower image of the complete cluster is a ground-based observation from the Digitized Sky Survey 2. The upper right image shows the full field of view of the Hubble Space Telescope. The upper left image highlights the region containing the galaxy Bedin 1.

Should the next-generation, much-delayed James Webb Space Telescope launch in 2021, there might be a few good years of overlapping observations between the space observatories so that astronomers can compare and contrast what the telescope sees. Who knows, maybe James Webb will peer at this newly found galaxy! It's not out of the realm of possibility, given that one of the goals of this new telescope is to learn more about early galaxies.

The intriguing results were published late last month in the journal Monthly Notices of the Royal Astronomical Society: Letters. The work was led by Luigi Bedin, from Italy's National Institute for Astrophysics, at the Astronomical Observatory of Padua.

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Feast your eyes on some truly awe-inspiring space images in "Hubble's Universe: Greatest Discoveries and Latest Images" by Terence Dickinson. We handpick reading recommendations we think you may like. If you choose to make a purchase, Curiosity will get a share of the sale.

Written by Elizabeth Howell February 6, 2019

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