Globular clusters are relatively common in our sky, and generally look similar. However, this image, taken using the NASA/ESA Hubble Space Telescope, shows a unique example of such a cluster — Palomar 2.
Palomar 2 is part of a group of 15 globulars known as the Palomar clusters. These clusters, as the name suggests, were discovered in survey plates from the first Palomar Observatory Sky Survey in the 1950s, a project that involved some of the most well-known astronomers of the day, including Edwin Hubble. They were discovered quite late because they are so faint — each is either extremely remote, very heavily hidden behind blankets of dust, or has a very small number of remaining stars.
This particular cluster is unique in more than one way. For one, it is the only globular cluster that we see in this part of the sky, the northern constellation of Auriga (The Charioteer). Globular clusters orbit the centre of a galaxy like the Milky Way in the same way that satellites circle around the Earth. This means that they normally lie closer in to the galactic centre than we do, and so we almost always see them in the same region of the sky. Palomar 2 is an exception to this, as it is around five times further away from the centre of the Milky Way than other clusters. It also lies in the opposite direction — further out than Earth — and so it is classed as an “outer halo” globular.
It is also unusual due to its brightness. The cluster is veiled by a mask of dust, dampening the apparent brightness of the stars within it and making it appear as a very faint burst of stars. The stunning NASA/ESA Hubble Space Telescope image above shows Palomar 2 in a way that could not be captured from smaller or ground-based telescopes — some amateur astronomers with large telescopes attempt to observe all of the obscure and well-hidden Palomar 15 as a challenge, to see how many they can pick out from the starry sky.
Bright aurora illuminating the sky over Norway (near Tromsø) on 17 February 2013.
ATV Albert Einstein is fuelled at Europe's Spaceport in Kourou, French Guiana. Automated Transfer Vehicles (ATVs) carry two types of propellant to the International Space Station. Aside from its own propellants, the space ferry brings propellants for the Russian Station thrusters. They are loaded in four phases – and each component is highly toxic. All non-essential personnel are cleared from the room and operators wear sealed ‘scape suits’ at all times during fuelling.
ATVs are multi-purpose unmanned ferries delivered to orbit by Europe’s Ariane 5 launcher. Each spacecraft can deliver up to 7 tonnes of cargo to the International Space Station, including supplies and equipment, water, air, nitrogen, oxygen and fuel.
ESA astronaut Luca Parmitano, tests his spacesuit, or Extravehicular Mobility Unit (EMU), to make sure it fits at NASA's Johnson Space Center, USA.
Proba-V atop the Vespa (Vega Secondary Payload Adapter) adapter on 15 April 2013. The minisatellite will ride the adapter to orbit during its flight in May, with its fellow passengers stowed within it: Vietnam’s VNREDSat Earth observation mission and Estonia’s ESTCube-1 student nanosatellite, to test electric solar sail technology. The Vega launcher fairing is seen in the background.
Artist’s impression of starburst galaxy HFLS3. The galaxy appears as little more than a faint, red smudge in images from ESA’s Herschel space observatory, but appearances can be deceiving for it is making stars more than 2000 times faster than our own Milky Way, one of the highest star formation rates ever seen in any galaxy. Amazingly, it is seen at a time when the Universe was less than a billion years old, challenging galaxy evolution theories.
Read the full story: Star factory in the early Universe challenges galaxy evolution theory
An area in the northwest of the Democratic Republic of Congo is pictured in this image taken on 26 June 2011 by the French SPOT-4 satellite. Most of the lighter green areas are deforested, while the darker green are areas of dense – and possibly natural – vegetation. The lines cutting through the image are roads, many with structures built along them. Clusters of purple dots are larger settlements. A river snakes through the upper part of the image and below it there appears to be a square in light green. Judging by the precision of the outline, we can deduce that this is a patch of land that was either intentionally spared from deforestation or has been reforested.
This image is featured on the Earth from Space video programme.
The Horsehead Nebula as viewed at near-infrared wavelengths (1.1 microns (blue/cyan) and 1.6 microns (red/orange)) with the Wide Field Camera 3 on the NASA/ESA Hubble Space Telescope. The image is approximately 6 arcminutes across and is oriented with north to the left and east down.
This thick pillar of gas and dust is sculpted by powerful stellar winds blowing from clusters of massive stars located beyond the field of this image. The bright source at the top left edge of the nebula is a young star whose radiation is already eroding the surrounding interstellar material.
Week In Images
15-19 April 2013