Picture of the Week

7 December 2020: An orange glow radiates from the centre of NGC 1792, the heart of this stellar forge. Captured by the NASA/ESA Hubble Space Telescope, this intimate view of NGC 1792 gives us some insight into this galactic powerhouse. The vast swathes of tell-tale blue seen throughout the galaxy indicate areas that are full of young, hot stars, and it is in the shades of orange, seen nearer the centre, that the older, cooler stars reside. Nestled in the constellation of Columba (The Dove), NGC 1792 is both a spiral galaxy, and a starburst galaxy. Within starburst galaxies, stars are forming at comparatively exorbitant rates. The rate of star formation can be more than 10 times faster in a starburst galaxy than in the Milky Way. When galaxies have a large resevoir of gas, like NGC 1792, these short lived starburst phases can be sparked by galactic events such as mergers and …

16 November 2020: Observed with the NASA/ESA Hubble Space Telescope, the faint galaxy featured in this image is known as UGC 12588. Unlike many spiral galaxies, UGC 12588 displays neither a bar of stars across its centre nor the classic prominent spiral arm pattern. Instead, to a viewer, its circular, white and mostly unstructured centre makes this galaxy more reminiscent of a cinnamon bun than a mega-structure of stars and gas in space. Lying in the constellation of Andromeda in the Northern hemisphere, this galaxy is classified as a spiral galaxy. Unlike the classic image of a spiral galaxy, however, the huge arms of stars and gas in UGC 12588 are very faint, undistinguished, and tightly wound around its centre. The clearest view of the spiral arms comes from the bluer stars sprinkled around the edges of the galaxy that highlight the regions where new star formation is most likely taking place.

26 October 2020: Appearing within the boundless darkness of space, the NASA/ESA Hubble Space Telescope’s snapshot of NGC 34 looks more like an otherworldly, bioluminescent creature from the deep oceans than a galaxy. Lying in the constellation Cetus (The Sea Monster), the galaxy’s outer region appears almost translucent, pinpricked with stars and strange wispy tendrils. The main cause for this galaxy’s odd appearance lies in its past. If we were able to reverse time by a few million years, we would see two beautiful spiral galaxies on a direct collision course. When these galaxies collided into one another, their intricate patterns and spiral arms were permanently disturbed. This image shows the galaxy's bright centre, a result of this merging event that has created a burst of new star formation and lit up the surrounding gas. As the galaxies continue to intertwine and become one, NGC 34’s shape will become more like that of …

5 October 2020: At around 60 million light-years from Earth, the Great Barred Spiral Galaxy NGC 1365 is captured beautifully in this image by the NASA/ESA Hubble Space Telescope. Located in the constellation of Fornax (The Furnace), the blue and fiery orange swirls show us where stars have just formed and the dusty sites of future stellar nurseries. At the outer edge of the image, enormous star-forming regions within NGC 1365 can be seen. The bright, light-blue regions indicate the presence of hundreds of baby stars that formed from coalescing gas and dust within the galaxy's outer arms. This Hubble image was captured as part of a joint survey with the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile. The survey will help scientists understand how the diversity of galaxy environments observed in the nearby Universe, including NGC 1365 and previous ESA/Hubble Pictures of the Week such as NGC 2835 and NGC 2775, influence …

28 September 2020: This stunning image by the NASA/ESA Hubble Space Telescope features the spiral galaxy NGC 5643 in the constellation of Lupus (The Wolf). Looking this good isn’t easy; thirty different exposures, for a total of 9 hours observation time, together with the high resolution and clarity of Hubble, were needed to produce an image of such high level of detail and of beauty. NGC 5643 is about 60 million light-years away from Earth and has been the host of a recent supernova event (not visible in this latest image). This supernova (2017cbv) was a specific type in which a white dwarf steals so much mass from a companion star that it becomes unstable and explodes. The explosion releases significant amounts of energy and lights up that part of the galaxy. The observation was proposed by Adam Riess, who was awarded a Nobel Laureate in physics 2011 for his contributions to the …

21 September 2020: Resting on the tail of the Great Bear in the constellation of Ursa Major, lies NGC 5585, a spiral galaxy that is more than it appears. The many stars, and dust and gas clouds that make up NGC 5585, shown here in this Hubble image, contribute only a small fraction of the total mass of the galaxy. As in many galaxies, this discrepancy can be explained by the abundant yet seemingly invisible presence of dark matter. The stellar disc of the galaxy extends over 35 000 light-years across. When compared with galaxies of a similar shape and size, NGC 5585 stands out by having a notably different composition: Contributing to the total mass of the galaxy, it contains a far higher proportion of dark matter. Hotspots of star formation can be seen along the galaxy’s faint spiral arms. These regions shine a brilliant blue, contrasting strikingly against the ever-black background …

14 September 2020: The twisting patterns created by the multiple spiral arms of NGC 2835 create the illusion of an eye. This is a fitting description, as this magnificent galaxy resides near the head of the southern constellation of Hydra, the water snake. This stunning barred spiral galaxy, with a width of just over half that of the Milky Way, is brilliantly featured in this image taken by the NASA/ESA Hubble Space Telescope. Although it cannot be seen in this image, a supermassive black hole with a mass millions of times that of our Sun is known to nestle in the very centre of NGC 2835 . This galaxy was imaged as part of PHANGS-HST, a large galaxy survey with Hubble that aims to study the connections between cold gas and young stars in a variety of galaxies in the local Universe. Within NGC 2835, this cold, dense gas produces large numbers of …

31 August 2020: The blue and orange stars of the faint galaxy named NGC 2188 sparkle in this image taken with the NASA/ESA Hubble Space Telescope. Although NGC 2188 appears at first glance to consist solely of a narrow band of stars, it is classified by astronomers as a barred-spiral galaxy. It appears this way from our viewpoint on Earth as the centre and spiral arms of the galaxy are tilted away from us, with only the very narrow outer edge of the galaxy’s disc visible to us. Astronomers liken this occurrence to turning a dinner plate in your hands so you see only its outer edge. The true shape of the galaxy was identified by studying the distribution of the stars in the inner central bulge and outer disc and by observing the stars’ colours. NGC 2188 is estimated to be just half the size of our Milky Way, at 50 000 …

3 August 2020: The barred spiral galaxy known as NGC 4907 shows its best side from 270 million light-years away to anyone who can see it from the northern hemisphere.This is a new image from the NASA/ESA Hubble Space Telescope of the face-on the galaxy, displaying its beautiful spiral arms, wound loosely around its central bright bar of stars. Shining brightly below the galaxy is a star that is actually within our own Milky Way galaxy. This star appears much brighter than the many millions of stars in NGC 4907 as it is 100 000 times closer, residing only 2500 light-years away. NGC 4907 is also part of the Coma Cluster, a group of over 1000 galaxies, some of which can be seen around NGC 4907 in this image. This massive cluster of galaxies lies within the constellation of Coma Berenices, which is named for the locks of Queen Berenice II of Egypt: …

20 July 2020: A notable feature of most spiral galaxies is the multitude of arching spiral arms that seemingly spin out from the galaxy’s centre. In this image, taken with the NASA/ESA Hubble Space Telescope, the stunning silvery-blue spiral arms of the galaxy NGC 4848 are observed in immense detail. Not only do we see the inner section of the spiral arms containing hundreds of thousands of young, bright, blue stars, but Hubble has also captured the extremely faint wispy tails of the outer spiral arms. This wispy barred spiral galaxy was first discovered in 1865 by the German astronomer Heinrich Louis d’Arrest. In his career, Heinrich also notably discovered the asteroid 76 Freia and many other galaxies and he also contributed to the discovery of Neptune. If you are situated in the Northern Hemisphere with a large telescope, you might just be able to observe the ghost-like appearance of this faint galaxy …

6 July 2020: Captured by the NASA/ESA Hubble Space Telescope, this image shows NGC 7513, a barred spiral galaxy. Located approximately 60 million light-years away, NGC 7513 lies within the Sculptor constellation in the southern hemisphere. This galaxy is moving at the astounding speed of 1564 kilometres per second, and it is heading away from us. For context, the Earth orbits the Sun at about 30 kilometres per second. Though NGC 7513’s apparent movement away from the Milky Way might seem strange, it is not that unusual. While some galaxies, like the Milky Way and the Andromeda galaxy, are caught in each other’s gravitational pull and will eventually merge together, the vast majority of galaxies in our Universe appear to be moving away from each other. This phenomenon is due to the expansion of the Universe, and it is the space between galaxies that is stretching, rather than the galaxies themselves moving.

29 June 2020: The spiral pattern shown by the galaxy in this image from the NASA/ESA Hubble Space Telescope is striking because of its delicate, feathery nature. These "flocculent" spiral arms indicate that the recent history of star formation of the galaxy, known as NGC 2775, has been relatively quiet. There is virtually no star formation in the central part of the galaxy, which is dominated by an unusually large and relatively empty galactic bulge, where all the gas was converted into stars long ago. NGC 2275 is classified as a flocculent spiral galaxy, located 67 million light-years away in the constellation of Cancer. Millions of bright, young, blue stars shine in the complex, feather-like spiral arms, interlaced with dark lanes of dust. Complexes of these hot, blue stars are thought to trigger star formation in nearby gas clouds. The overall feather-like spiral patterns of the arms are then formed by shearing of …

22 June 2020: The galaxy known as NGC 5907 stretches wide across this image. Appearing as an elongated line of stars and dark dust, the galaxy is categorised as a spiral galaxy just like our own Milky Way. In this new image from the NASA/ESA Hubble Space Telescope, we don’t see the beautiful spiral arms because we are viewing it edge-on, like looking at the rim of a plate. It is for this reason that NGC 5907 is also known as the Knife Edge Galaxy. The Knife Edge Galaxy is about 50 million light-years from Earth, lying in the northern constellation of Draco. Although not visible in this image, ghostly streams of stars on large arching loops extend into space, circling around the galaxy; they are believed to be remnants of a small dwarf galaxy, torn apart by the Knife Edge Galaxy and merged with it over four billion years ago.

8 June 2020: Looking deep into the Universe, the NASA/ESA Hubble Space Telescope catches a passing glimpse of the numerous arm-like structures that sweep around this barred spiral galaxy, known as NGC 2608. Appearing as a slightly stretched, smaller version of our Milky Way, the peppered blue and red spiral arms are anchored together by the prominent horizontal central bar of the galaxy. In Hubble photos, bright Milky Way stars will sometimes appear as pinpoints of light with prominent lens flares. A star with these features is seen in the lower right corner of the image, and another can be spotted just above the pale centre of the galaxy. The majority of the fainter points around NGC 2608, however, lack these features, and upon closer inspection they are revealed to be thousands of distant galaxies. NGC 2608 is just one among an uncountable number of kindred structures. Similar expanses of galaxies can be …

25 May 2020: Far away in the Ursa Major constellation is a swirling galaxy that would not look out of place on a coffee made by a starry-eyed barista. NGC 3895 is a barred spiral galaxy that was first spotted by William Herschel in 1790 and was later observed by the NASA/ESA Hubble Space Telescope. Hubble's orbit high above the Earth's distorting atmosphere allows astronomers to make the very high resolution observations that are essential to opening new windows on planets, stars and galaxies — such as this beautiful view of NGC 3895. The telescope is positioned approximately 570 km above the ground, where it whirls around Earth at 28 000 kilometres per hour and takes 96 minutes to complete one orbit.

18 May 2020: Unlike a spiral or elliptical galaxy, the galaxy KK 246 looks like glitter spilled across a black velvet sheet. KK 246, also known as ESO 461-036, is a dwarf irregular galaxy residing within the Local Void, a vast region of empty space. This lonely galaxy is the only one known for certain to reside in this enormous volume, along with 15 others that have been tentatively identified. Although the picture appears to be full of galaxies, they are actually beyond this void, and instead form part of other galaxy groups or clusters. Cosmic voids, such as this one, are the spaces within the web-like structure of the Universe wherein very few or no galaxies exist. Adjacent to the Local Group, this region of empty space is at least 150 million light-years across. For perspective, our own Milky Way galaxy is estimated to be 150 000 light-years across, making this void …

11 May 2020: Approximately 85 million light-years from Earth, in the constellation of Libra, is the beautiful galaxy NGC 5861, captured here by the NASA/ESA Hubble Space Telescope. NGC 5861 is an intermediate spiral galaxy. Astronomers classify most galaxies by their morphology. For example, the Milky Way galaxy is a barred spiral galaxy. An intermediate spiral galaxy has a shape lying in between that of a barred spiral galaxy, one that appears to have a central bar-shaped structure, and that of an unbarred spiral galaxy, one without a central bar. Two supernovae, SN1971D and SN2017erp, have been observed in the galaxy. Supernovae are powerful and luminous explosions that can light up the night sky. The brightest supernova ever recorded was possibly SN 1006. It shone 16 times as bright as Venus from April 30 to May 1, 1006 AD.

4 May 2020: In the forests of the night lies a barred spiral galaxy called NGC 3583, imaged here by the NASA/ESA Hubble Space Telescope. This is a barred spiral galaxy with two arms that twist out into the Universe. This galaxy is located 98 million light-years away from the Milky Way. Two supernovae exploded in this galaxy, one in 1975 and another, more recently, in 2015. There are a few different ways that supernova can form. In the case of these two supernovae, the explosions evolved from two independent binary star systems in which the stellar remnant of a Sun-like star, known as a white dwarf, was collecting material from its companion star. Feeding off of its partner, the white dwarf gorged on the material until it reached a maximum mass. At this point, the star collapsed inward before exploding outward in a brilliant supernova. Two of these events were spotted in …

27 April 2020: This sparkling spiral galaxy looks almost stretched across the sky in this new image from the NASA/ESA Hubble Space Telescope. Known as NGC 4100, the galaxy boasts a neat spiral structure and swirling arms speckled with the bright blue hue of newly formed stars. Like so many of the stunning images of galaxies we enjoy today, this image was captured by Hubble’s Advanced Camera for Surveys (ACS). This remarkable instrument was installed in 2002, and, with some servicing over the years by intrepid astronauts, is still going strong. You can access many of the stunning images captured by the ACS here, featuring objects from out-of-this-world spiral galaxies to dark, imposing nebulae, bizarre cosmic phenomena, and sparkling clusters made up of thousands upon thousands of stars.

13 April 2020: This image depicts a swirling spiral galaxy named NGC 2906. The blue speckles seen scattered across this galaxy are massive young stars, which emit hot, blue-tinged radiation as they burn through their fuel at an immense rate. The swathes of orange are a mix of older stars that have swollen and cooled, and low-mass stars that were never especially hot to begin with. Owing to their lower temperatures, these stars emit a cooler, reddish, radiation. This image of NGC 2906 was captured by the NASA/ESA Hubble Space Telescope’s Wide Field Camera 3, an instrument installed on Hubble in 2009 during the telescope’s fourth servicing mission. Hubble observed this galaxy on the hunt for fading light from recent, nearby occurrences of objects known as supernovae.