This image shows a lonely galaxy known as Wolf-Lundmark-Melotte, or WLM for short. Although considered part of our Local Group of dozens of galaxies, WLM stands alone at the group’s outer edges as one of its most remote members. In fact, WLM is so small and secluded that it may never have interacted with any other galaxy in the history of the universe.
In this image from NASA’s Cassini spacecraft we see a crater duo on Saturn’s 698-mile-wide moon Dione. The upper of the pair, named Italus, is overprinted on a grouping of ancient troughs called Petelia Fossae. The lower crater, Caieta, sits atop a feature named Helorus Fossa. Fossae on Dione are believed to be tectonic features.
At first glance, this cosmic kaleidoscope of purple, blue and pink offers a strikingly beautiful — and serene — snapshot of the cosmos. However, this multi-coloured haze actually marks the site of two colliding galaxy clusters, forming a single object known as MACS J0416.1-2403 (or MACS J0416 for short), 4.3 billion light-years away from Earth.
On 14 March, the ExoMars spacecraft and Schiaparelli lander were lofted into orbit by a Proton rocket, starting a seven-month journey to the Red Planet. For the ExoMars launch, ESA’s near-Earth object (NEO) coordination centre in Italy organised a successful international campaign for ground-based optical observations of the departing spacecraft.
MACS J0717, some 5.4 billion light-years away from Earth in the constellation of Auriga (The Charioteer), is the result of four galaxy clusters colliding. This image is a combination of observations in visible light, X-rays and radio waves from the NASA/ESA Hubble Space Telescope, NASA’s Chandra X-ray Observatory, and the NRAO Jansky Very Large Array.
Far in the dwarf planet’s western hemisphere, scientists on NASA’s New Horizons mission have discovered what looks like a giant “bite mark” on Pluto’s surface. They suspect that the methane ice-rich surface on Pluto may be sublimating away into the atmosphere, exposing a layer of water-ice underneath.
Similar in many ways, Saturn’s moons Tethys and Rhea (left and right, respectively) even share a discoverer: Giovanni Cassini, namesake of the NASA spacecraft that captured this view. Although somewhat different in size, Rhea (949 miles across) and Tethys (660 miles) are both composed largely of ices and are generally thought to be geologically inactive today.
This planetary nebula is known as Kohoutek 4-55 (or K 4-55). It is one of a series of planetary nebulae that were named after their discoverer, Czech astronomer Luboš Kohoutek. Such a nebula is formed from material in the outer layers of a red giant star that are expelled into interstellar space when the star is in the late stages of its life.
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