Dancing on the edge: 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 of the week. 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 would be very impressive even without NGC 7814 in front; nearly all the objects seen in this image are galaxies as well. A version of this image was entered into the Hubble’s Hidden Treasures image processing competition by contestant Josh Barrington.

Name: NGC 7814
Type: Local Universe : Galaxy : Type : Spiral
Category: Galaxies
Constellation: Pegasus
Distance: 40 million light years
Release date: 2 February 2015, 10:00
Credit: Credit: ESA/Hubble & NASAAcknowledgement: Josh Barrington

A smiling lens: In the centre of this image, taken with the NASA/ESA Hubble Space Telescope, are two faint galaxies that seem to be smiling. You can make out two orange eyes and a white button nose. In the case of this “happy face”, the two eyes are the galaxies SDSSCGB 8842.3 and SDSSCGB 8842.4 and the misleading smile lines are actually arcs caused by an effect known as strong gravitational lensing. Massive structures in the Universe exert such a powerful gravitational pull that they can warp the spacetime around them and act as cosmic lenses which can magnify, distort and bend the light behind them. This phenomenon, crucial to many of Hubble’s discoveries, can be explained by Einstein’s theory of general relativity. In this special case of gravitational lensing, a ring  — known as an Einstein Ring  — is produced from this bending of light, a consequence of the exact and symmetrical alignment of the source, lens and observer and resulting in the ring-like structure we see here. Hubble has provided astronomers with the tools to probe these massive galaxies and model their lensing effects, allowing us to peer further into the early Universe than ever before. This object was studied by Hubble’s Wide Field and Planetary Camera 2 (WFPC2) and Wide Field Camera 3 (WFC3) as part of a survey of strong lenses. A version of this image was entered into the Hubble’s Hidden Treasures image processing competition by contestant Judy Schmidt.

Name: SDSSCGB 8842.3, SDSSCGB 8842.4
Type: Local Universe : Galaxy : Type : Gravitationally LensedLocal Universe : Galaxy : Grouping : Cluster
Category: Cosmology
Constellation: Ursa Major
Release date: 9 February 2015, 10:00
Credit: NASA & ESA Acknowledgement: Judy Schmidt (geckzilla.org)

Panta rhei — motion in the Milky Way: Panta rhei is a simplified version of the famous greek philosopher Heraclitus' teachings. It basically means, everything flows. And everything in the Universe is indeed continually on the move, spiralling and shifting through space. Some cosmic objects move a little further than others — take the subject of this NASA/ESA Hubble Space Telescope image, a globular cluster of stars known as Palomar 12. Although it currently lies on the outskirts of the Milky Way’s halo, Palomar 12 was not born here. When astronomers first studied this cluster, they were puzzled by its strangely young age when compared to the other clusters in the galaxy. It appeared to be around 30% younger than other Milky Way globulars. Surely if it had been born within our galaxy, it would have sprung to life at a similar time to its cluster companions? A bit more digging revealed that Palomar 12 was actually ripped from its initial home, the Sagittarius Dwarf Elliptical galaxy, around 1.7 billion years ago via tidal interactions between its former home and our galaxy. The dwarf galaxy that Palomar 12 once called home is a satellite galaxy to ours, and closely orbits around us — even occasionally passing through the plane of our galaxy. In fact, it is being slowly torn apart and consumed by the Milky Way. The sparkling stars in this picture were imaged by Hubble’s Advanced Camera for Surveys.

Name: Palomar 12
Type: Milky Way : Star : Grouping : Cluster : Globular
Category: Star Clusters
Constellation: Capricornus
Distance: 60000 light years
Release date: 16 February 2015, 10:00
Credit: ESA/Hubble & NASA

A galactic cloak for an exploding star: The galaxy pictured here is NGC 4424, located in the constellation of  Virgo. It is not visible with the naked eye but has been captured here with the NASA/ESA Hubble Space Telescope. Although it may not be obvious from this image, NGC 4424 is in fact a spiral galaxy. In this image it is seen more or less edge on, but from above you would be able to see the arms of the galaxy wrapping around its centre to give the characteristic spiral form . In 2012 astronomers observed a supernova in NGC 4424 — a violent explosion marking the end of a star’s life. During a supernova explosion, a single star can often outshine an entire galaxy. However, the supernova in NGC 4424, dubbed SN 2012cg, cannot be seen here as the image was taken ten years prior to the explosion. Along the central region of the galaxy, clouds of dust block the light from distant stars and create dark patches. To the left of NGC 4424 there are two bright objects in the frame. The brightest is another, smaller galaxy known as LEDA 213994 and the object closer to NGC 4424 is an anonymous star in our Milky Way. A version of this image was entered into the Hubble's Hidden Treasures image processing competition by contestant Gilles Chapdelaine.

Name: NGC 4424
Type: Local Universe : Galaxy : Type : Spiral
Category: Galaxies
Constellation: Virgo
Distance: 50 million light years
Release date: 23 February 2015, 10:00
Credit: ESA/Hubble & NASAAcknowledgement: Gilles Chapdelaine

A young star takes centre stage: With its helical appearance resembling a snail’s shell, this reflection nebula seems to spiral out from a luminous central star in this new NASA/ESA Hubble Space Telescope image. The star in the centre, known as V1331 Cyg and located in the dark cloud LDN 981 — or, more commonly, Lynds 981 — had previously been defined as a T Tauri star. A T Tauri is a young star — or Young Stellar Object — that is starting to contract to become a main sequence star similar to the Sun. What makes V1331Cyg special is the fact that we look almost exactly at one of its poles. Usually, the view of a young star is obscured by the dust from the circumstellar disc and the envelope that surround it. However, with V1331Cyg we are actually looking in the exact direction of a jet driven by the star that is clearing the dust and giving us this magnificent view. This view provides an almost undisturbed view of the star and its immediate surroundings allowing astronomers to study it in greater detail and look for features that might suggest the formation of a verylow-mass object in the outer circumstellar disc.

Name: V1331 Cyg
Type: Local Universe : Star : Evolutionary Stage : Young Stellar ObjectLocal Universe : Star : Type : VariableLocal Universe : Nebula : Appearance : Reflection
Category: Stars
Constellation: Cygnus
Distance: 1800 light years
Release date: 2 March 2015, 10:00
Credit: ESA/Hubble, NASA, Karl Stapelfeldt (GSFC), B. Stecklum and A. Choudhary (Thüringer Landessternwarte Tautenburg, Germany)