Sculpted by stellar winds and radiation, the star factory known as Messier 17 lies some 5,500 light-years away in the nebula-rich constellation Sagittarius. At that distance, this 1/3 degree wide field of view spans over 30 light-years. The sharp composite, color image, highlights faint details of the region’s gas and dust clouds against a backdrop of central Milky Way stars. Stellar winds and energetic light from hot, massive stars formed from M17 stock of cosmic gas and dust have slowly carved away at the remaining interstellar material producing the cavernous appearance and undulating shapes. M17 is also known as the Omega Nebula or the Swan Nebula.
Image Credit: ESA/Hubble and NASA
Beautiful island universe Messier 94 lies a mere 15 million light-years distant in the northern constellation of the hunting dogs, Canes Venatici. A popular target for earth-based astronomers, the face-on spiral galaxy is about 30,000 light-years across, with spiral arms sweeping through the outskirts of its broad disk. But this Hubble Space Telescope field of view spans about 7,000 light-years or so across M94’s central region. The sharp close-up examines the galaxy’s compact, bright nucleus and prominent inner dust lanes, surrounded by a remarkable bluish ring of young, massive stars. The massive stars in the ring are all likely less than 10 million years old, indicating the galaxy experienced a well-defined era of rapid star formation. As a result, while the small, bright nucleus is typical of the Seyfert class of active galaxies, M94 is also known as a starburst galaxy. Because M94 is relatively nearby, astronomers can explore in detail the reasons for the galaxy’s burst of star formation.
Image Credit: NASA, Johns Hopkins U. APL, SwRI
What do the moons of Pluto look like? Before a decade ago, only the largest moon Charon was known, but never imaged. As the robotic New Horizons spacecraft was prepared and launched, other moons were identified on Hubble images but remained only specks of light. Finally, this past summer, New Horizons swept right past Pluto, photographed Pluto and Charonin detail, and took the best images of Styx, Nix, Kerberos, and Hydra that it could. The featured image composite shows the results — each moon is seen to have a distinct shape, while underlying complexity is only hinted. Even though not satisfyingly resolved, these images are likely to be the best available to humanity for some time. This is because the moons are too small and distant for contemporary Earth-based telescopes to resolve, and no new missions to the Pluto system are planned.