Artist's impression of a magnetar with a ‘magnetic loop'. This is the interpretation of data collected by ESA’s XMM-Newton space telescope of the magnetar known as SGR 0418, which boasts one of the strongest magnetic fields in the Universe. In order to maintain such a strong magnetic field, the magnetar must have a twisted internal magnetic field, which manifests itself as a small region on the star’s surface, somewhat similar to the localised magnetic fields anchored in sunspots on the Sun.
A radar view of the southern highlands of Mars, captured by the Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) instrument on ESA’s Mars Express. The radar track covers 5580 km and features the Hellas Basin at the far right, and the south polar ice cap with its associated layered deposits just left of centre.
The gap to the left of the south pole is an artificial effect due to a distortion in the measurements; it does not correspond to any geological feature.
The image was first highlighted by The Planetary Society’s blogger Bill Dunford, in his Exploring ten years’ worth of Mars Express Data entry featured in June.
Astronomical pictures sometimes deceive us with tricks of perspective. Right in the centre of this image, two spiral galaxies appear to be suffering a spectacular collision, with a host of stars appearing to flee the scene of the crash in a chaotic stampede.
However, this is just a trick of perspective. It is true that two spiral galaxies are colliding, but they are millions of light-years away, far beyond the cloud of blue and red stars near the merging spiral. This sprinkling of stars is actually an isolated, irregular dwarf galaxy named ESO 489-056. The dwarf galaxy is actually much more distant than many bright stars in the foreground of the image, which are located much closer to us, in the Milky Way.
ESO 489-056 is located 16 million light-years from Earth in the constellation of Canis Major (The Greater Dog), in our local Universe. It is composed of a few billion red and blue stars — a very small number when compared to galaxies like the Milky Way, which is estimated to contain around 200 to 400 billion stars, or the Andromeda Galaxy, which contains a mind-boggling one trillion.
A version of this image was entered into the Hubble's Hidden Treasures image processing competition by contestant Luca Limatola.
Week in Images
12-16 August 2013