A Bright Supernova in the Nearby Galaxy NGC 2403

The explosion of a massive star blazes with the light of 200 million Suns in this NASA/ESA Hubble Space Telescope image. The arrow at top right points to the stellar blast, called a supernova. The supernova is so bright in this image that it easily could be mistaken for a foreground star in our Milky Way Galaxy. And yet, this supernova, called SN 2004dj, resides far beyond our galaxy. Its home is in the outskirts of NGC 2403, a galaxy located 11 million light-years from Earth. Although the supernova is far from Earth, it is the closest stellar explosion discovered in more than a decade.

Image Credit: NASA, ESA, A.V. Filippenko
Explanation from: https://www.spacetelescope.org/images/opo0423a/

Planetary Nebula NGC 7027

This composite colour image of NGC 7027 is among the first data of a planetary nebula taken with NICMOS. This picture is actually composed of three separate images taken at different wavelengths. The red colour represents cool molecular hydrogen gas, the most abundant gas in the Universe.

Image Credit: William B. Latter (SIRTF Science Center/Caltech) and NASA/ESA

Clouds over Pacific Ocean seen from the International Space Station

ISS, Orbit of the Earth

September 2016

Image Credit: NASA/ESA

Sunrise seen from the International Space Station

ISS, Orbit of the Earth

September 2016

Image Credit: NASA/ESA

Spiral Galaxy NGC 3274

This image of the spiral galaxy NGC 3274 comes courtesy of the NASA/ESA Hubble Space Telescope’s Wide Field Camera 3 (WFC3). Hubble’s WFC3 vision spreads from the ultraviolet light through to the near infrared , allowing astronomers to study a wide range of targets, from nearby star formation through to galaxies in the most remote regions of the cosmos.

This particular image combines observations gathered in five different filters, bringing together ultraviolet, visible, and infrared light to show off NGC 3274 in all its glory. As with all of the data Hubble sends back to Earth, it takes advantage of the telescope’s location in space above our planet’s distorting atmosphere. WFC3 returns clear, crisp, and detailed images time after time.

NGC 3274 is a relatively faint galaxy located over 20 million light-years away in the constellation of Leo (The Lion). The galaxy was discovered by Wilhelm Herschel in 1783. The galaxy PGC 213714 is also visible on the upper right of the frame, located much further away from Earth.

Image Credit: ESA/Hubble & NASA, D. Calzetti
Explanation from: https://www.spacetelescope.org/images/potw1647a/

Large Magellanic Cloud Galaxy & Small Magellanic Cloud Galaxy seen over Auxiliary Telescopes of the VLT Array at ESO's Paranal Observatory on Cerro Paranal in Chile

This beautiful image taken at ESO's Paranal Observatory shows the four Auxiliary Telescopes of the Very Large Telescope (VLT) Array, set against an incredibly starry backdrop on Cerro Paranal in Chile.

The Auxiliary Telescopes are each 1.8 metres in diameter and work with the four 8.2-metre diameter Unit Telescopes to make up the world's most advanced optical observatory.

The telescopes work together to form the VLT Interferometer (VLTI), a giant interferometer which allows astronomers to see details up to 25 times finer than would be possible with the individual Unit Telescopes.

Hanging over the site are the prominent Small and Large Magellanic Clouds, visible only in the southern sky. These two irregular dwarf galaxies are in the Local Group and so are companion galaxies to our own galaxy, the Milky Way.

Image Credit: ESO/J. Colosimo
Explanation from: https://www.eso.org/public/images/potw1511a/

Open Star Cluster NGC 299

It may be famous for hosting spectacular sights such as the Tucana Dwarf Galaxy and 47 Tucanae, the second brightest globular cluster in the night sky, but the southern constellation of Tucana (The Toucan) also possesses a variety of unsung cosmic beauties.

One such beauty is NGC 299, an open star cluster located within the Small Magellanic Cloud just under 200 000 light-years away. Open clusters such as this are collections of stars weakly bound by the shackles of gravity, all of which formed from the same massive molecular cloud of gas and dust. Because of this, all the stars have the same age and composition, but vary in their mass because they formed at different positions within the cloud.

This unique property not only ensures a spectacular sight when viewed through a sophisticated instrument attached to a telescope such as Hubble’s Advanced Camera for Surveys, but gives astronomers a cosmic laboratory in which to study the formation and evolution of stars — a process that is thought to depend strongly on a star’s mass.

Image Credit: ESA/Hubble & NASA
Explanation from: https://www.spacetelescope.org/images/potw1642a/

Spiral Galaxy NGC 4388

The constellation of Virgo (The Virgin) is especially rich in galaxies, due in part to the presence of a massive and gravitationally-bound collection of over 1300 galaxies called the Virgo Cluster. One particular member of this cosmic community, NGC 4388, is captured in this image, as seen by the NASA/ESA Hubble Space Telescope’s Wide Field Camera 3 (WFC3).

Located some 60 million light-years away, NGC 4388 is experiencing some of the less desirable effects that come with belonging to such a massive galaxy cluster. It is undergoing a transformation, and has taken on a somewhat confused identity.

While the galaxy’s outskirts appear smooth and featureless, a classic feature of an elliptical galaxy, its centre displays remarkable dust lanes constrained within two symmetric spiral arms, which emerge from the galaxy’s glowing core — one of the obvious features of a spiral galaxy. Within the arms, speckles of bright blue mark the locations of young stars, indicating that NGC 4388 has hosted recent bursts of star formation.

Despite the mixed messages, NGC 4388 is classified as a spiral galaxy. Its unusual combination of features are thought to have been caused by interactions between NGC 4388 and the Virgo Cluster. Gravitational interactions — from glancing blows to head-on collisions, tidal influencing, mergers, and galactic cannibalism — can be devastating to galaxies. While some may be lucky enough to simply suffer a distorted spiral arm or newly-triggered wave of star formation, others see their structure and contents completely and irrevocably altered.

Image Credit: ESA/Hubble & NASA
Explanation from: https://www.spacetelescope.org/images/potw1649a/

Clouds over Pacific Ocean seen from the International Space Station

ISS, Orbit of the Earth

September 2016

Image Credit: NASA/ESA

Dusty filaments in elliptical galaxy NGC 4696

New observations from the NASA/ESA Hubble Space Telescope have revealed the intricate structure of the galaxy NGC 4696 in greater detail than ever before. The elliptical galaxy is a beautiful cosmic oddity with a bright core wrapped in system of dark, swirling, thread-like filaments.

NGC 4696 is a member of the Centaurus galaxy cluster, a swarm of hundreds of galaxies all sitting together, bound together by gravity, about 150 million light-years from Earth and located in the constellation of Centaurus.

Despite the cluster’s size, NGC 4696 still manages to stand out from its companions — it is the cluster’s brightest member, known for obvious reasons as the Brightest Cluster Galaxy . This puts it in the same category as some of the biggest and brightest galaxies known in the Universe.

Even if NGC 4696 keeps impressive company, it has a further distinction: the galaxy’s unique structure. Previous observations have revealed curling filaments that stretch out from its main body and carve out a cosmic question mark in the sky, the dark tendrils encircling a brightly glowing centre.

An international team of scientists, led by astronomers from the University of Cambridge, UK, have now used new observations from the NASA/ESA Hubble Space Telescope to explore this thread-like structure in more detail. They found that each of the dusty filaments has a width of about 200 light-years, and a density some 10 times greater than the surrounding gas. These filaments knit together and spiral inwards towards the centre of NGC 4696, connecting the galaxy’s constituent gas to its core.

In fact, it seems that the galaxy’s core is actually responsible for the shape and positioning of the filaments themselves. At the centre of NGC 4696 lurks an active supermassive black hole. This floods the galaxy’s inner regions with energy, heating the gas there and sending streams of heated material outwards.

It appears that these hot streams of gas bubble outwards, dragging the filamentary material with them as they go. The galaxy’s magnetic field is also swept out with this bubbling motion, constraining and sculpting the material within the filaments.

At the very centre of the galaxy, the filaments loop and curl inwards in an intriguing spiral shape, swirling around the supermassive black hole at such a distance that they are dragged into and eventually consumed by the black hole itself.

Understanding more about filamentary galaxies such as NGC 4696 may help us to better understand why so many massive galaxies near to us in the Universe appear to be dead; rather than forming newborn stars from their vast reserves of gas and dust, they instead sit quietly, and are mostly populated with old and aging stars. This is the case with NGC 4696. It may be that the magnetic structure flowing throughout the galaxy stops the gas from creating new stars.

Image Credit: NASA, ESA/Hubble, A. Fabian
Explanation from: https://www.spacetelescope.org/news/heic1621/

Earth seen from the International Space Station

ISS, Orbit of the Earth

September 2016

Image Credit: NASA/ESA

Aurora over Alaska

Alaska, USA

Image Credit & Copyright: Mark Thiessen

Preview of a forthcoming supernova: the Eta Carinae

At the turn of the 19th century, the binary star system Eta Carinae was faint and undistinguished. In the first decades of the century, it became brighter and brighter, until, by April 1843, it was the second brightest star in the sky, outshone only by Sirius (which is almost a thousand times closer to Earth). In the years that followed, it gradually dimmed again and by the 20th century was totally invisible to the naked eye.

The star has continued to vary in brightness ever since, and while it is once again visible to the naked eye on a dark night, it has never again come close to its peak of 1843.

The larger of the two stars in the Eta Carinae system is a huge and unstable star that is nearing the end of its life, and the event that the 19th century astronomers observed was a stellar near-death experience. Scientists call these outbursts supernova impostor events, because they appear similar to supernovae but stop just short of destroying their star.

Although 19th century astronomers did not have telescopes powerful enough to see the 1843 outburst in detail, its effects can be studied today. The huge clouds of matter thrown out a century and a half ago, known as the Homunculus Nebula, have been a regular target for Hubble since its launch in 1990. This image, taken with the Advanced Camera for Surveys High Resolution Channel is the most detailed yet, and shows how the material from the star was not thrown out in a uniform manner, but forms a huge dumbbell shape.

Eta Carinae is not only interesting because of its past, but also because of its future. It is one of the closest stars to Earth that is likely to explode in a supernova in the relatively near future (though in astronomical timescales the “near future” could still be a million years away). When it does, expect an impressive view from Earth, far brighter still than its last outburst: SN 2006gy, the brightest supernova ever observed, came from a star of the same type.

This image consists of ultraviolet and visible light images from the High Resolution Channel of Hubble’s Advanced Camera for Surveys. The field of view is approximately 30 arcseconds across.

Image Credit: ESA/Hubble & NASA
Explanation from: https://www.spacetelescope.org/images/potw1208a/

Aurora, Milky Way Galaxy, Large Magellanic Cloud Galaxy and Small Magellanic Cloud Galaxy seen over New Zealand

Queenstown, New Zealand

March 12, 2016

Image Credit & Copyright: Minoru Yoneto

Clouds over Indian Ocean seen from the International Space Station

ISS, Orbit of the Earth

September 2016

Image Credit: NASA/ESA

The IC 3583 Galaxy

This delicate blue group of stars — actually an irregular galaxy named IC 3583 — sits some 30 million light-years away in the constellation of Virgo (The Virgin).

It may seem to have no discernable structure, but IC 3583 has been found to have a bar of stars running through its centre. These structures are common throughout the Universe, and are found within the majority of spiral, many irregular, and some lenticular galaxies. Two of our closest cosmic neighbours, the Large and Small Magellanic Clouds, are barred, indicating that they may have once been barred spiral galaxies that were disrupted or torn apart by the gravitational pull of the Milky Way.

Something similar might be happening with IC 3583. This small galaxy is thought to be gravitationally interacting with one of its neighbours, the spiral Messier 90. Together, the duo form a pairing known as Arp 76. It’s still unclear whether these flirtations are the cause of IC 3583’s irregular appearance — but whatever the cause, the galaxy makes for a strikingly delicate sight in this NASA/ESA Hubble Space Telescope image, glimmering in the blackness of space.

Image Credit: ESA/Hubble & NASA
Explanation from: https://www.spacetelescope.org/images/potw1648a/

Earth's Atmosphere, Sunrise and Clouds over Atlantic Ocean seen from the International Space Station

ISS, Orbit of the Earth

September 2016

Image Credit: NASA/ESA

Aurora over Nordland

Høgtuva, Nordland, Norway

October 25, 2011

Image Credit & Copyright: Tommy Eliassen

Trapezium Cluster in the Orion Nebula

Appearing like glistening precious stones, the Trapezium cluster's central region is here seen through the eyes of the NASA/ESA Hubble Space Telescope. All of the celestial objects in the Trapezium were born together in this hotbed of star formation. The cluster is named for the trapezoidal alignment of those central massive stars.

Probing deep within a neighborhood stellar nursery, NASA/ESA Hubble Space Telescope uncovered a swarm of newborn brown dwarfs. The orbiting observatory's near-infrared camera revealed about 50 of these objects throughout the Orion Nebula's Trapezium cluster about 1, 500 light-years from Earth.

Image Credit: X-ray: NASA/CXC/SAO; Optical: NASA/STScI; Radio: NSF/NRAO/AUI/VLA)
Explanation from: http://www.spacetelescope.org/images/opo0019b/

Laser Guide Star & VLT Telescopes

This image shows one of the four Unit Telescopes that make up ESO’s Very Large Telescope (VLT) at Paranal. Each of the 8.2-metre telescopes was given a name in the Mapuche language spoken by indigenous people from the Southern Chile. The Unit Telescope in this image is called Yepun, which means Venus.

The smaller telescope beside Yepun is one of four Auxiliary Telescopes that have a diameter of 1.8 metres. These can be combined with the Unit Telescopes to make the Very Large Telescope Interferometer (VLTI).

Yepun is equipped with the Laser Guide Star Facility that is caught in action in this picture. The laser beam’s colour is precisely tuned to energise a layer of sodium atoms in the atmosphere which creates a small bright spot — an artificial star. This star can be used as a reference to work out how much the atmosphere is distorting the light from actual stars — a process called adaptive optics — which helps to develop clear images.

Above Yepun you can see part of the Milky Way galaxy stretching across the southern sky. The brighter regions on the lower right correspond to the Large Magellanic Cloud and Small Magellanic Cloud — two satellite galaxies of the Milky Way.

Image Credit: ESO/Y. Beletsky
Explanation from: https://www.eso.org/public/images/potw1547a/

Bear Lake seen from the International Space Station

ISS, Orbit of the Earth

September 2016

Bear Lake, Utah/Idaho, USA

Image Credit: NASA/ESA