Lonely planets, Martian tracks and charred Soyuz - in pictures

A backlit droplet of heptane fuel burns in microgravity on the International Space Station. Fuels burn very differently in the absence of gravity. Image-processing techniques quantify the soot concentration at each point to produce a grey-scale image, which is then colourised. This is a composite of individual video frames Photograph: Nasa Photograph: Action images This image from Nasa's Spitzer Space Telescope shows a stellar nursery containing thousands of young stars and developing protostars near the sword of the constellation Orion. Massive stars light up the Orion nebula, the bright region near the centre of the image. To the north of the nebula is a dark filamentary cloud of cold dust and gas over five light years long, containing ruby red protostars that jewel the hilt of Orion's sword Photograph: Spitzer Space Telescope/NASA A diver simulates anchoring to the surface of an asteroid, part of Nasa's Extreme Environment Mission Operations project . Moving around on the surface of an asteroid – with little or no gravity to hold astronauts or vehicles in place – will require several anchors linked to form pathways Photograph: NASA Some 90 years ago, Edwin Hubble used pulsating stars called cepheids to demonstrate that the universe extends far beyond our own galaxy . He proved that these stars were too far away to be part of our Milky Way galaxy. The circle in the box, top right, marks the location of one of the cepheids he used, in the galaxy Andromeda . At first he thought it was an exploding star (labelling it N for nova) but then realised it was a cepheid variable, crossing out the N and writing 'VAR!' Photograph: Hubble Heritage/NASA/ESA These curious tracks on Mars were left by the rover Opportunity on its lonely trek between craters on the Red Planet. For an explanation of the periodic sidesteps, click here Photograph: JPL-Caltech/NASA The European Southern Observatory's Very Large Telescope combined forces with Nasa's Cassini spacecraft to study a rare storm in the normally placid atmosphere of Saturn . It's only the sixth storm of this size to be seen on the planet since 1876 Photograph: ESO/NASA Testing the Grail twins: Technicians prepare to hoist Grail-A out of a vacuum chamber after tests to see how well the two spacecraft will weather the rigours of space. The craft, scheduled for launch late this summer, will orbit the moon and measure its gravity field in unprecedented detail Photograph: JPL-Caltech/LMSS/Nasa Photograph: JPL-Caltech/LMSS /Action images This image of the shuttle Endeavour launching on its final mission on 16 May cleverly combines six images shot at different exposures to reveal previously unseen detail , for example in the bright rocket exhaust. Processing software digitally removes pure black or pure white pixels from one image and replaces them with the best exposed corresponding pixel from the five other images. The technique can help identify debris falling during launch Photograph: Nasa Photograph: Action images Endeavour bursts through clouds on its way to Earth orbit and a final rendezvous with the International Space Station . This unusual photo was taken on 16 May from a Nasa shuttle training aircraft Photograph: NASA Astronaut Andrew Feustel re-enters the space station after completing an eight-hour spacewalk on 22 May Photograph: ISS/NASA Endeavour docked to the International Space Station. The picture was taken by departing astronaut Paolo Nespoli from a homeward-bound Soyuz after it undocked on 24 May Photograph: ESA/Nasa Photograph: Action images Soyuz, scorched by its fiery re-entry, after it landed in a remote area southeast of the town of Zhezkazgan, Kazakhstan Photograph: Bill Ingalls/Nasa Photograph: Bill Ingalls/Action images Jets and radio-emitting lobes shoot from the supermassive black hole at the centre of the galaxy Centaurus A. The image – from Nasa's Chandra X-ray Observatory – is a composite of visible, microwave (orange) and x-ray (blue) data Photograph: ESO/Nasa Photograph: MPIfR/ESO/APEX/A.Weiss et al. (microwave); NASA/CXC/CfA/R.Kraft et al. (X-ray)/ESO/WFI (visible) One of the prizes in an international Earth and sky photography contest went to Stephane Vetter for this photo of the northern lights and Milky Way over an Arctic landscape in Iceland Photograph: Stephane Vetter/TWAN Photograph: Stephane Vetter/Action images The Lagoon nebula captured in all its psychedelic glory by the Gemini Observatory in Hawaii Photograph: Gemini Observatory/AURA Photograph: Julia I. Arias and Rodolfo H. Barbá Departamento de Física, Universidad de La Serena (Chile), and ICATE-CONICET (Argentina)./Gemini Observatory/AURA Artist's impression of a Jupiter-like planet floating free in the immensity of space. Astronomers uncovered evidence for 10 such worlds , which are thought to have been "booted" from developing solar systems Photograph: JPL-Caltech/NASA A dwarf galaxy ablaze with young stars and gas clouds 10m light-years away in the constellation of Canes Venatici (The Hunting Dogs) Photograph: Hubble Heritage/Esa/Nasa Photograph: Hubble Heritage/Action images