This week’s image from the Hubble Space Telescope shows a small but intriguing galaxy called UGC 7983, which is thought to resemble some of the earliest galaxies to exist in the universe. Located 30 million light-years away in the constellation Virgo, it looks like a hazy fuzz and is small enough to be considered a dwarf galaxy. Their unusual shape also puts them in a specific type called a dwarf irregular galaxy.
In addition to the show’s galactic star, the frame of the image is dotted with galaxies of all kinds visible in the background, as well as many nearby stars dotting the image that are much closer than the background galaxies.
Astronomers are interested in studying dwarf galaxies like this one to learn more about how galaxies formed in the early Universe. Researchers know that galaxies that formed when the Universe was young, in the first few billion years after the Big Bang, were very different from most galaxies we see today. And we know that irregular dwarf galaxies tend to have large amounts of dust and gas within them, making them hotbeds of star formation.
Dwarf galaxies were important during a period of the universe called the epoch of reionization, when early stars began to spread first light throughout the universe. That’s why the James Webb Space Telescope studies dwarf galaxies like the nearby Small Magellanic Cloud to learn more about how early stars and galaxies might have formed.
Not only is this image important for learning about the early Universe, but it also has another interesting feature. In the upper left you can see a streak of light produced by a small asteroid that happened to be passing when the image was taken. If you look very closely you can see that the strip is divided into four lines representing the four exposures that were combined to create the final image.