The two images show ultraviolet light ranging from 1,600 to 3,300 angstroms, a range of light that is largely blocked by the Earth's atmosphere. The two images were taken using the Swift satellite’s Ultraviolet/Optical telescope (UVOT), and have a cumulative total exposure time of 7.2 days.
The larger of the two surveys shows the Large Magellanic Cloud (LMC), a galaxy that resides 163,000 light-years away and measures some 14,000 light-years across. The 160-megapixel survey was stitched together from more 2,200 individual images taken by the UVOT telescope, and reveals nearly a million ultraviolet sources within the LMC. The most prominent object in the LMC is the Tarantula Nebula, one of the largest and most active star-forming areas in the Local Group galaxies.
The second survey shows the Small Magellanic Cloud (SMC), an object that measures around 7,000 light-years across and resides some 200,000 light-years away. The LMC and SMC orbit each other while in turn orbiting the much larger Milky Way galaxy. The 57-megapixel image of the Small Magellanic Cloud contains 250,000 ultraviolet sources and was assembled from 656 separate shots of the object.
Despite the spectacular detail of the images, neither of the galaxies in question are particularly large, comparatively speaking. The LMC is about one-tenth the size of our own Milky Way galaxy and contains just one percent of its mass, while the SMC is half the size of its bigger brother and contains about two-thirds of its mass. The galaxies appear large in the night sky due to their close proximity to the Earth.
The new images are the highest-resolution ultraviolet surveys of the Megallanic Clouds ever made. NASA's Stefan Immler commented on the significance of the project, stating that “With these mosaics, we can study how stars are born and evolve across each galaxy in a single view, something that's very difficult to accomplish for our own galaxy because of our location inside it,"
The UVOT telescope has been used on similar projects in the past. In 2009 it produced an impressive ultraviolet image of the Andromeda Galaxy, an object that resides some 2.5 million light-years away.
Though the UVOT's images are undoubtedly impressive, in terms of sheer scale, they pale in comparison to the European Space Observatory's gigantic 9-gigapixel image of the Milky Way taken by the Visible and Infrared Survey Telescope for Astronomy (VISTA) last year. The image of our home galaxy contains some 84 million stars and and measures a spectacular 108,500 x 81,500 pixels.
Click the source link to take a closer look at the astonishing images of the Magellanic Clouds.