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Saturn sits nested in its rings of ice as Cassini once again plunges toward the graceful giant. This natural color mosaic was acquired by the Cassini spacecraft as it soared 39 degrees above the unilluminated side of the rings. Little light makes its way through the rings to be scattered in Cassini's direction in this viewing geometry, making the rings appear somewhat dark compared to the reflective planet. The view can be contrasted with earlier mosaics designed to showcase the rings rather than the planet, which were therefore given longer exposure times. Bright clouds play in the blue-gray skies of the north. The ring shadows continue to caress the planet as they slide farther south toward their momentary disappearance during equinox in 2009. The rings' reflected light illuminates the southern hemisphere on Saturn's night side. The scene is reminiscent of the parting glance of NASA's Voyager 1 as it said goodbye to Saturn in 1981. Cassini, however, will continue to o...

A colourful star-forming region is featured in this stunning NASA/ESA Hubble Space Telescope image of NGC 2467. Looking like a roiling cauldron of some exotic cosmic brew, huge clouds of gas and dust are sprinkled with bright blue, hot young stars. Strangely shaped dust clouds, resembling spilled liquids, are silhouetted against a colourful background of glowing. Like the familiar Orion Nebula, NGC 2467 is a huge cloud of gas — mostly hydrogen — that serves as an incubator for new stars. This picture was created from images taken with the Wide Field Channel of the Advanced Camera for Surveys through three different filters (F550M, F660N and F658N, shown in blue, green and red). These filters were selected to let through different colours of red and yellow light arising from different elements in the gas. The total aggregate exposure time was about 2000 seconds and the field of view is about 3.5 arcminutes across. These data were taken in 2004. Image Credit: NASA, ESA and Orsola De Marc...

The aurora borealis over Høgtuva Mountain in Norway. The Earth's magnetic field funnels particles from the solar wind over the polar regions. More than 80 kilometres above the ground, these collide with molecules in the atmosphere causing them to glow: green and pale red for oxygen and crimson for nitrogen. Image Credit & Copyright: Tommy Eliassen Explanation by: Royal Observatory Greenwich

Galaxies can take many shapes and be oriented any way relative to us in the sky. This can make it hard to figure out their actual morphology, as a galaxy can look very different from different viewpoints. A special case is when we are lucky enough to observe a spiral galaxy directly from its edge, providing us with a spectacular view like the one seen in this picture. This is NGC 7814, also known as the “Little Sombrero”. Its larger namesake the Sombrero Galaxy is another stunning example of an edge-on galaxy — in fact, the “Little Sombrero” is about the same size as its bright namesake at about 60 000 light-years across, but as it lies further away, it appears smaller in the sky. NGC 7814 has a bright central bulge and a bright halo of glowing gas extending outwards into space. The dusty spiral arms appear as dark streaks. they consist of dusty material that absorbs and blocks light from the galactic centre behind it. The field of view of this NASA/ESA Hubble Space Telescope image wou...

Hubble has captured the most detailed image to date of the open star cluster NGC 290 in the Small Magellanic Cloud. The image taken with the Advanced Camera for Surveys onboard the NASA/ESA Hubble Space Telescope show a myriad of stars in crystal clear detail. The brilliant open star cluster, NGC 290, is located about 200,000 light-years away and is roughly 65 light-years across. Image Credit: European Space Agency & NASA

The closest star system to the Earth is the famous Alpha Centauri group. Located in the constellation of Centaurus (The Centaur), at a distance of 4.3 light-years, this system is made up of the binary formed by the stars Alpha Centauri A and Alpha Centauri B, plus the faint red dwarf Alpha Centauri C, also known as Proxima Centauri. The NASA/ESA Hubble Space Telescope has given us this stunning view of the bright Alpha Centauri A (on the left) and Alpha Centauri B (on the right), flashing like huge cosmic headlamps in the dark. The image was captured by the Wide Field and Planetary Camera 2 (WFPC2). WFPC2 was Hubble’s most used instrument for the first 13 years of the space telescope’s life, being replaced in 2009 by WFC3 during Servicing Mission 4. This portrait of Alpha Centauri was produced by observations carried out at optical and near-infrared wavelengths. Compared to the Sun, Alpha Centauri A is of the same stellar type G2, and slightly bigger, while Alpha Centauri B, a K1-type ...

This wide-field view of the star-forming region NGC 281 in the constellation Cassiopeia was taken with the WIYN 0.9-meter telescope at Kitt Peak National Observatory near Tucson, Arizona, USA Image Credit: T.A. Rector/University of Alaska Anchorage and WIYN/AURA/NSF

This oddly colorful nebula is the supernova remnant IC 443 as seen by NASA's Wide-field Infrared Survey Explorer, or WISE. Also known as the Jellyfish nebula, IC 443 is particularly interesting because it provides a look into how stellar explosions interact with their environment. IC 443 can be found near the star Eta Geminorum, which lies near Castor, one of the twins in the constellation Gemini. Just like human beings, stars have a life cycle -- they are born, mature and eventually die. The manner in which stars die depends on their mass. Stars with mass similar to the sun typically become planetary nebulae at the end of their lives, whereas stars with many times the sun's mass explode as supernovae. IC 443 is the remains of a star that went supernova somewhere between 5,000 and 10,000 years ago. The blast from the supernova sent out shock waves that traveled through space, sweeping up and heating the surrounding gas and dust in the interstellar medium, and creating the super...

Omega Centauri has been known as an unusual globular cluster for a long time. A new result obtained by the NASA/ESA Hubble Space Telescope and the Gemini Observatory reveals that the explanation behind Omega Centauri's peculiarities may be a black hole hidden in its centre. One implication of the discovery is that it is very likely that Omega Centauri is not a globular cluster at all, but a dwarf galaxy stripped of its outer stars, as some scientists have suspected for a few years. A new discovery has resolved some of the mystery surrounding Omega Centauri, the largest and brightest globular cluster in the sky. Images obtained with the Advanced Camera for Surveys onboard the NASA/ESA Hubble Space Telescope and data obtained by the GMOS spectrograph on the Gemini South telescope in Chile show that Omega Centauri appears to harbour an elusive intermediate-mass black hole in its centre. "This result shows that there is a continuous range of masses for black holes, from supermassi...

Observations with ESO’s Very Large Telescope have revealed that the giant elliptical galaxy Messier 87 has swallowed an entire medium-sized galaxy over the last billion years. For the first time a team of astronomers has been able to track the motions of 300 glowing planetary nebulae to find clear evidence of this event and also found evidence of excess light coming from the remains of the totally disrupted victim. Astronomers expect that galaxies grow by swallowing smaller galaxies. But the evidence is usually not easy to see — just as the remains of the water thrown from a glass into a pond will quickly merge with the pond water, the stars in the infalling galaxy merge in with the very similar stars of the bigger galaxy leaving no trace. But now a team of astronomers led by PhD student Alessia Longobardi at the Max-Planck-Institut für extraterrestrische Physik, Garching, Germany has applied a clever observational trick to clearly show that the nearby giant elliptical galaxy Messier 8...

Venus is the second planet from the Sun, orbiting it every 224.7 Earth days. It has the longest rotation period (243 days) of any planet in the Solar System and rotates in the opposite direction to most other planets. It has no natural satellite. It is named after the Roman goddess of love and beauty. It is the second-brightest natural object in the night sky after the Moon, reaching an apparent magnitude of −4.6, bright enough to cast shadows. Because Venus is an inferior planet from Earth, it never appears to venture far from the Sun; its elongation reaches a maximum of 47.8°. Venus is a terrestrial planet and is sometimes called Earth's "sister planet" because of their similar size, mass, proximity to the Sun, and bulk composition. It is radically different from Earth in other respects. It has the densest atmosphere of the four terrestrial planets, consisting of more than 96% carbon dioxide. The atmospheric pressure at the planet's surface is 92 times that of Earth...

A bright star is surrounded by a tenuous shell of gas in this unusual image from the NASA/ESA Hubble Space Telescope. U Camelopardalis, or U Cam for short, is a star nearing the end of its life. As it begins to run low on fuel, it is becoming unstable. Every few thousand years, it coughs out a nearly spherical shell of gas as a layer of helium around its core begins to fuse. The gas ejected in the star’s latest eruption is clearly visible in this picture as a faint bubble of gas surrounding the star. U Cam is an example of a carbon star. This is a rare type of star whose atmosphere contains more carbon than oxygen. Due to its low surface gravity, typically as much as half of the total mass of a carbon star may be lost by way of powerful stellar winds. Located in the constellation of Camelopardalis (The Giraffe), near the North Celestial Pole, U Cam itself is actually much smaller than it appears in Hubble’s picture. In fact, the star would easily fit within a single pixel at the centre...

This true color mosaic of Jupiter was constructed from images taken by the narrow angle camera onboard NASA's Cassini spacecraft on December 29, 2000, during its closest approach to the giant planet at a distance of approximately 10 million kilometers (6.2 million miles). It is the most detailed global color portrait of Jupiter ever produced; the smallest visible features are approximately 60 kilometers (37 miles) across. The mosaic is composed of 27 images: nine images were required to cover the entire planet in a tic-tac-toe pattern, and each of those locations was imaged in red, green, and blue to provide true color. Although Cassini's camera can see more colors than humans can, Jupiter's colors in this new view look very close to the way the human eye would see them. Everything visible on the planet is a cloud. The parallel reddish-brown and white bands, the white ovals, and the large Great Red Spot persist over many years despite the intense turbulence visible in the a...

Image of globular cluster NGC 6397 in the constellation Ara (the Altar). The cluster is home to a highly unusual system consisting of a fast spinning pulsar and a bloated red companion star. Image Credit: NASA, ESA and H. Richer (University of British Columbia)

This image shows the galaxy Messier 94, which lies in the small northern constellation of the Hunting Dogs, about 16 million light-years away. Within the bright ring around Messier 94 new stars are forming at a high rate and many young, bright stars are present within it – thanks to this, this feature is called a starburst ring. The cause of this peculiarly shaped star-forming region is likely a pressure wave going outwards from the galactic centre, compressing the gas and dust in the outer region. The compression of material means the gas starts to collapse into denser clouds. Inside these dense clouds, gravity pulls the gas and dust together until temperature and pressure are high enough for stars to be born. Image Credit: ESA/Hubble & NASA Explanation from: https://www.spacetelescope.org/images/potw1542a/

This colourful view shows the star-forming region LHA 120-N44 in the Large Magellanic Cloud, a small satellite galaxy of the Milky Way. This picture combines the view in visible light from the MPG/ESO 2.2-metre telescope at ESO’s La Silla Observatory in Chile with images in infrared light and X-rays from orbiting satellite observatories. At the centre of this very rich region of gas, dust and young stars lies the star cluster NGC 1929. Its massive stars produce intense radiation, expel matter at high speeds as stellar winds, and race through their short but brilliant lives to explode as supernovae. The winds and supernova shock waves have carved out a huge cavity, called a superbubble, in the surrounding gas. Observations with NASA's Chandra X-ray Observatory (shown here in blue) reveal hot regions created by these winds and shocks, while infrared data from NASA's Spitzer Space Telescope (shown in red) outline where the dust and cooler gas are found. The visible-light view from...

Home to some of the largest stars ever discovered, the open stellar cluster Pismis 24 blazes from the core of NGC 6357, a nebula in the constellation of Scorpius (the Scorpion). Several stars in the clusters weigh in at over 100 times the mass of the Sun, making them real monster stars. The strange shapes taken by the clouds are a result of the huge amount of blazing radiation emitted by these massive, hot stars. The gas and dust of the nebula hide huge baby stars in the nebula from telescopes observing in visible light, as well as adding to the hazy appearance of the image. This image combines observations performed through three different filters in visible light (B, V, R) with the 1.5-metre Danish telescope at the ESO La Silla Observatory in Chile. Image Credit: ESO/IDA/Danish 1.5 m/ R. Gendler, U.G. Jørgensen, J. Skottfelt, K. Harpsøe Explanation from: https://www.eso.org/public/images/potw1015a/

Our magnificent Milky Way galaxy is radiant over La Silla Observatory. The ESO 3.6-metre telescope is shown to the right, now home to the world's foremost extrasolar planet hunter: High Accuracy Radial velocity Planet Searcher (HARPS), a spectrograph with unrivalled precision. Image Credit: ESO/B. Tafreshi