星系

NGC 3175 is located around 50 million light-years away in the constellation of Antlia (the Air Pump). The galaxy can be seen slicing across the frame in this image from the NASA/ESA Hubble Space Telescope, with its mix of bright patches of glowing gas, dark lanes of dust, bright core, and whirling, pinwheeling arms coming together to paint a beautiful celestial scene. The galaxy is the eponymous member of the NGC 3175 group, which has been called a nearby analog for the Local Group. The Local Group contains our very own home galaxy, the Milky Way, and around 50 others — a mix of spiral, irregular and dwarf galaxies. The NGC 3175 group contains a couple of large spiral galaxies — the subject of this…

For this image, the NASA/ESA Hubble Space Telescope turned its powerful eye toward an emission-line galaxy called NGC 3749. When astronomers explore the contents and constituent parts of a galaxy somewhere in the universe, they use various techniques and tools. One of these is to spread out the incoming light from that galaxy into a spectrum and explore its properties. This is done in much the same way as a glass prism spreads white light into its constituent wavelengths to create a rainbow. By hunting for specific signs of emission from various elements within a galaxy’s spectrum of light —so-called emission lines — or, conversely, the signs of absorption from other elements — so-called absorption lines — astronomers can start to deduce what might be…

The universe is simply so vast that it can be difficult to maintain a sense of scale. Many galaxies we see through telescopes such as the NASA/ESA Hubble Space Telescope, the source of this beautiful image, look relatively similar: spiraling arms, a glowing center, and a mixture of bright specks of star formation and dark ripples of cosmic dust weaving throughout. This galaxy, a spiral galaxy named NGC 772, is no exception. It actually has much in common with our home galaxy, the Milky Way. Each boasts a few satellite galaxies, small galaxies that closely orbit and are gravitationally bound to their parent galaxies. One of NGC 772’s spiral arms has been distorted and disrupted by one of these satellites (NGC 770 — not visible…

The galaxy pictured in this Hubble image has an especially evocative name: the Medusa merger. Often referred to by its somewhat drier New General Catalogue designation of NGC 4194, this was not always one entity, but two. An early galaxy consumed a smaller gas-rich system, throwing out streams of stars and dust into space. These streams, seen rising from the top of the merged galaxy, resemble the writhing snakes that Medusa, a monster in ancient Greek mythology, famously had on her head in place of hair, lending the object its intriguing name. The legend of Medusa also held that anyone who saw her face would transform into stone. In this case, you can feast your eyes without fear on the center of the merged galaxy,…

The center of our Milky Way galaxy is hidden from the prying eyes of optical telescopes by clouds of obscuring dust and gas. But in this stunning vista, the Spitzer Space Telescope’s infrared cameras penetrate much of the dust, revealing the stars of the crowded galactic center region. The upcoming James Webb Space Telescope will offer a much-improved infrared view, teasing out fainter stars and sharper details. The center of our galaxy is a crowded place: A black hole weighing 4 million times as much as our Sun is surrounded by millions of stars whipping around it at breakneck speeds. This extreme environment is bathed in intense ultraviolet light and X-ray radiation. Yet much of this activity is hidden from our view, obscured by vast…

Many of the best-loved galaxies in the cosmos are remarkably large, close, massive, bright, or beautiful, often with an unusual or intriguing structure or history. However, it takes all kinds to make a universe — as demonstrated by this Hubble image of Messier 110. Messier 110 may not look like much, but it is a fascinating near neighbor of our home galaxy, and an unusual example of its type. It is a member of the Local Group, a gathering of galaxies comprising the Milky Way and a number of the galaxies closest to it. Specifically, Messier 110 is one of the many satellite galaxies encircling the Andromeda galaxy, the nearest major galaxy to our own, and is classified as a dwarf elliptical galaxy, meaning that…

Located in the northern constellation of Ursa Major, which also includes the Big Dipper, nearby galaxy Messier 81 is easily visible through binoculars or a small telescope. M81 is located at a distance of 12 million light-years. M81 was one of the first publicly released datasets soon after the launch of the Spitzer Space Telescope in August 2003. On the occasion of Spitzer’s 16th anniversary this new image revisits this iconic object with extended observations and improved processing. This Spitzer infrared image is a composite mosaic combining data from the Infrared Array Camera (IRAC) at wavelengths of 3.6/4.5 microns (blue/cyan) and 8 microns (green) with data from the Multiband Imaging Photometer (MIPS) at 24 microns (red). The 3.6-micron near-infrared data (blue) traces the distribution of…

The pair of strange, luminescent creatures at play in this image are actually galaxies — realms of millions upon millions of stars. This galactic duo is known as UGC 2369. The galaxies are interacting, meaning that their mutual gravitational attraction is pulling them closer and closer together and distorting their shapes in the process. A tenuous bridge of gas, dust and stars can be seen connecting the two galaxies, created when they pulled material out into space across the diminishing divide between them. Interaction with others is a common event in the history of most galaxies. For larger galaxies like the Milky Way, the majority of these interactions involve significantly smaller so-called dwarf galaxies. But every few billion years, a more momentous event can occur….