This colourful cosmic rainbow portrays a section of Saturn’s beautiful rings, four centuries after they were discovered by Galileo Galilei.
Saturn’s rings were first observed in 1610. Despite using his newly created telescope, Galileo was confounded by what he saw: he referred to the peculiar shapes surrounding the planet as “Saturn’s children”. Only later did Christiaan Huygens propose that the mysterious shapes were actually rings orbiting the planet. These were named in the order in which they were discovered, using the first seven letters of the alphabet: the D-ring is closest to the planet, followed by C, B, A, F, G and E.
The data for this image, which shows the portion of the C-ring closest to Saturn on the left, with the B-ring beginning just right of centre, were acquired by Cassini’s Ultraviolet Imaging Spectrograph, or UVIS, as the spacecraft entered into orbit around Saturn on 30 June 2004.
UVIS, as its name suggests, carries out observations in ultraviolet wavelengths. During the Saturn orbit insertion manoeuvre, when Cassini flew closest to the rings, UVIS could resolve features up to 97 km across. The region shown in this image spans about 10 000 km.
The variation in the colour of the rings arises from the differences in their composition. Turquoise-hued rings contain particles of nearly pure water ice, whereas reddish rings contain ice particles with more contaminants.
Saturn’s prominent and complex ensemble of rings is the best studied in the Solar System, but it is still not known how the rings formed. One suggestion is that they formed at the same time as the planet and that they are as old as the Solar System. Another idea is that they formed when icy material was pulled from another body into Saturn’s gravitational field, in which case the rings could be younger than the planet.
One thing is sure: as Cassini searches for answers it is providing amazing images of these rainbow rings.
The Cassini–Huygens mission is a cooperative project of NASA, ESA and Italy’s ASI space agency.
This image was first published at the NASA Cassini website, in 2004.
Members of ESA’s Solar Orbiter team watch expectantly as an essential part of the spacecraft is lowered into Europe’s largest vacuum chamber: the multi-layered shield that will protect their probe from the Sun’s remorseless glare.
This engineering model of the sunshield, sandwiched together from multiple layers of titanium and outermost carbon coating, was placed in the 15 m-high and 10 m-diameter Large Space Simulator at ESA’s Technical Centre, ESTEC, in Noordwijk, the Netherlands, on 2 May.
Solar Orbiter, due for launch in 2017, will carry a portfolio of instruments for high-resolution imaging of our parent star from as close as 42 million km – a little more than a quarter of the distance to Earth.
Operating in direct view of the Sun, the mission must endure 13 times the intensity of terrestrial sunlight and temperatures rising as high as 520°C.
The main body of the spacecraft will therefore be huddled behind a multi-layered 3.1 m by 2.4 m sunshield, with the circular holes for cameras to peep through, many behind protective glass or beryllium.
The question is, can the sunshield keep up the insulating performance the Solar Orbiter mission and its sensitive instruments demand?
As its crucial test begins, all air will be extracted to produce space-quality vacuum, while the chamber walls are pumped with –190°C liquid nitrogen to mimic the extreme cold of deep space.
Then the light from 19 xenon lamps, each consuming 25 kW, will be tightly focused by mirrors into a concentrated beam of artificial sunlight upon the sunshield for a number of days.
The roof of the Simulator can be seen in the left-hand background of the image, ready to slide into place to seal the chamber for testing.
This radar image is one of the first from the Sentinel-1A satellite, acquired on 20 April – less than three weeks after its launch on 3 April.
The image shows the Salar de Uyuni in Bolivia, which is the largest salt flat in the world.
Occupying over 10 000 sq km, the vast Salar de Uyuni lies at the southern end of the Altiplano, a high plain of inland drainage in the central Andes. Some 40 000 years ago, this area was part of a giant prehistoric lake that dried out, leaving behind the salt flat.
While the salt flat appears an almost homogenous white in optical satellite imagery, here we see it in shades of grey, and it looks almost like a lake. This has to do with how the radar signal reacts to different surfaces: areas where the radar signal is absorbed appear darker, while areas where the signal is reflected back to the satellite appear lighter. This gives Earth observation experts an indication of how rough or smooth the surfaces area, differences in salt density or even the presence of water.
But on the whole, the Salar de Uyuni is very flat, with a surface elevation variation of less than 1 m. This makes the area ideal for calibrating satellite radar altimeters – a different kind of radar instrument that measures surface topography. The future Sentinel-3 mission will carry a radar altimeter.
The surrounding terrain is rough in comparison to the vast salt flat and is dominated by the volcanoes of the Andes mountains forming part of the Pacific Ring of Fire.
Sentinel-1A is the first in the two-satellite Sentinel-1 mission for Europe’s Copernicus programme. Its radar data will be used for a variety of applications, including the surveillance of the marine environment, monitoring land-surface for motion risks, mapping for forest, water and soil management, and mapping to support humanitarian aid and crisis situations.
This image is featured on the Earth from Space video programme.
The Nile Delta in Egypt, acquired by Proba-V on 24 March 2014.
Celebrating one year since the miniature Proba-V satellite was launched from French Guiana in the early hours of 7 May 2013.
The 'V' stands for 'vegetation': the satellite was designed to provide a clear picture of the world’s plants so their health can be easily monitored. This information can also be used for day-by-day tracking of extreme weather, alerting authorities to crop failures, monitoring inland water resources and tracing the steady spread of deserts and deforestation.
See our gallery for more images from Proba-V's first year of operation:
This bundle of bright stars and dark dust is a dwarf spiral galaxy known as NGC 4605, located around 16 million light-years away in the constellation of Ursa Major (The Great Bear). This galaxy’s spiral structure is not obvious from this image, but NGC 4605 is classified as an SBc type galaxy — meaning that it has sprawling, loosely wound arms and a bright bar of stars cutting through its centre.
NGC 4605 is a member of the Messier 81 group of galaxies, a gathering of bright galaxies including its namesake Messier 81 (heic0710), and the well-known Messier 82 (heic0604a). Galaxy groups like this usually contain around 50 galaxies, all loosely bound together by gravity. This group is famous for its unusual members, many of which formed from collisions between galaxies. With its somewhat unusual form, NGC 4605 fits in well with the family of perturbed galaxies in the M81 group, although the origin of its abnormal features is not yet clear.
The Messier 81 group is one of the nearest groups to our own, the Local Group, which houses the Milky Way and some of its well-known neighbours, including the Andromeda Galaxy and the Magellanic Clouds. Galaxy groups provide environments where galaxies can evolve through interactions like collisions and mergers. These galaxy groups are then lumped together into even larger gatherings of galaxies known as clusters and superclusters. The Local and Messier 81 groups both belong to the Virgo Supercluster, a large and massive collection of some 100 galaxy groups and clusters.
With so many galaxies swarming around, NGC 4605 may seem unremarkable. However, astronomers are using this galaxy to test our knowledge of stellar evolution. The newly-formed stars in NGC 4605 are being used to investigate how interactions between galaxies affect the formation, evolution, and behaviour of the stars within, how bright stellar nurseries come together to form stellar clusters and stellar associations, and how these stars evolve over time.
And that's not all — NGC 4605 is also proving to be a good testing ground for dark matter. Our theories on this hypothetical type of matter have had good success at describing how the Universe looks and behaves on a large scale — for example at the galaxy supercluster level — but when looking at individual galaxies, they have run into problems. Observations of NGC 4605 show that the way in which dark matter is spread throughout its halo is not quite as these models predict. While intriguing, observations in this area are still inconclusive, leaving astronomers to ponder over the contents of the Universe.
The magnetic field of our Milky Way Galaxy as seen by ESA’s Planck satellite. This image was compiled from the first all-sky observations of polarised light emitted by interstellar dust in the Milky Way. The magnetic field is displayed using a visualisation technique called line integral convolution (LIC).
Darker regions correspond to stronger polarised emission, and the striations indicate the direction of the magnetic field projected on the plane of the sky. The dark band running horizontally across the centre corresponds to the Galactic Plane. Here, the polarisation reveals a regular pattern on large angular scales, which is due to the magnetic field lines being predominantly parallel to the plane of the Milky Way. The data also reveal variations of the polarisation direction within nearby clouds of gas and dust. This can be seen in the tangled features above and below the plane, where the local magnetic field is particularly disorganised.
The image is a Mollweide projection of the full celestial sphere, with the plane of the Galaxy aligned with the horizontal axis of the oval. Certain areas in the image, mostly at high Galactic latitude, have been masked out. The overall intensity in these regions is low, complicating the separation of foreground and cosmic microwave background (CMB) components. Further data analysis will improve this by the time of the full data release in late 2014.
Full story: Planck takes magnetic fingerprint of our Galaxy
Europe’s next two Galileo satellites being unloaded from the Boeing 747 cargo aircraft at Cayenne – Félix Eboué Airport in French Guiana in the early morning of 7 May 2014. The two satellites are scheduled to be launched together by Soyuz from Europe’s Spaceport this summer.
The fifth Automated Transfer Vehicle, ATV Georges Lemaître, is assembled at Europe's Spaceport in Kourou, French Guiana. The spacecraft's Integrated Cargo Carrier is lifted into position before being attached to the Service Module. ATV-5 is scheduled for launch to the International Space Station in July 2014, delivering supplies such as food, clothes and experiment equipment as well as fuel and water.
ESA astronaut Alexander Gerst (left) and NASA astronaut Reid Wiseman look on as their Expedition 40 commander Maxim Suarev signs exam forms. Today, the crew had their first day of tests on the Russian segment of the Space Station. If all goes well, they will be launched to the International Space Station 28 May.
Also passing their exams was the backup crew of ESA astronaut Samantha Cristoforetti, NASA astronaut Terry Virts and cosmonaut commander Anton Shkaplerov. They performed their first day of exams on the Soyuz spacecraft they will fly to the outpost. The backup crew will be launched in November as Expedition 42, once Expedition 40/41 are back on Earth.
Both exams last all day and see the astronauts dealing with a range of demanding scenarios, with the examiners surprising them with emergency situations.
At the Gagarin Cosmonaut Training Center in Star City, Russia, Expedition 40/41 Flight Engineer Alexander Gerst of the European Space Agency (front row, left) signs a ceremonial book during a tour of the Gagarin Museum as his crewmates and their backups look on.
Also pictured are Soyuz Commander Max Suraev of the Russian Federal Space Agency (Roscosmos, front row, centre) and Flight Engineer Reid Wiseman of NASA (front row, right) and backup crewmembers Terry Virts of NASA (back row, left), Anton Shkaplerov of Roscosmos (back row, centre) and Samantha Cristoforetti of the European Space Agency (back row, right).
Wiseman, Gerst, and Suraev are preparing for launch on 28 May from the Baikonur Cosmodrome in Kazakhstan on the Soyuz TMA-13M spacecraft for a five and a half month mission on the International Space Station.
With St. Basil’s Cathedral in the background at Moscow’s Red Square, Expedition 40/41 Flight Engineer Alexander Gerst of the European Space Agency (left), Soyuz Commander Max Suraev of the Russian Federal Space Agency (Roscosmos, centre) and Flight Engineer Reid Wiseman of NASA (right) pose for pictures after laying flowers at the Kremlin Wall where Russian space icons are interred.
The trio is preparing for launch on 28 May with the Soyuz TMA-13M spacecraft from the Baikonur Cosmodrome in Kazakhstan for a five and a half month mission on the International Space Station.
Week In Images
5-9 May 2014