Tropical Storm Irma seen by Suomi NPP satellite

On August 30 at 11:36 a.m. EDT (1536 UTC) NASA-NOAA's Suomi NPP satellite captured a visible image of Tropical Storm Irma in the Eastern Atlantic Ocean.

Image Credit: NASA/NOAA, Goddard Rapid Response Team

Galaxy Cluster ACT-CL J0102-4915

When astronomical objects are named, astronomers like to pick out notable features for inspiration — for example, the Whirlpool Galaxy with its pinwheeling arms, or the Needle Galaxy, which appears as a long, thin streak of silver across the sky.

This image shows a galaxy cluster known as El Gordo, or “the fat one”, a very distant object that lies some ten billion light-years away from us. This grouping of galaxies certainly lives up to its nickname; it is the largest known galaxy cluster in the distant Universe and contains several hundred galaxies. What’s more, new NASA/ESA Hubble Space Telescope observations show that it is actually some 43 percent heavier than previously thought, with a mass some three million billion times the mass of the Sun — which is 3000 times the mass of our own galaxy, the Milky Way.

A small fraction of the cluster’s immense mass is locked up in the galaxies that inhabit it, and a larger fraction is held in hot gas that fills its entire volume, but the majority is made up of the infamous, and invisible, dark matter. The location of this dark matter is mapped out in the blue overlay. Although galaxy clusters as massive as this do exist in the nearby Universe, for example the Bullet Cluster, nothing like this has ever been seen to exist so far back in time, when the Universe was roughly half of its current age of 13.8 billion years.

Astronomers previously weighed El Gordo back in January 2012, studying the unusual cluster’s appearance and dynamics in the X-ray part of the spectrum. This new Hubble study instead analysed how the huge cluster affected the space around it to get an idea of its mass. Large clumps of mass warp space and distort the view of more distant objects. This process, known as gravitational lensing, allows astronomers to estimate the mass of the clumps that are causing this distortion.

Image Credit: NASA, ESA, J. Jee (University of California, Riverside, USA)
Explanation from: https://www.spacetelescope.org/images/potw1414a/

New stars in Canis Major

Dozens of newborn stars sprouting jets from their dusty cocoons have been spotted in images from NASA's Spitzer Space Telescope. In this view showing a portion of sky near Canis Major, infrared data from Spitzer are green and blue, while longer-wavelength infrared light from NASA's Wide-field Infrared Survey Explorer (WISE) are red.

The jets appear in green, while young stars are a yellow-orange hue. Some of the jets can be seen as streaks, while others appear as blobs because only portions of the jet can be seen. In some cases, the stars producing jets can't be seen while their jets can. Those stars are so embedded in their dusty cocoon that they are too faint to be seen at Spitzer's wavelengths.

This is a lesser-known region of star formation, located near the outer edge of our Milky Way galaxy. Spitzer is showing that even these more sparse regions of the galaxy are aglow with stellar youth.

The pink hues are from organic star-forming molecules called polycyclic aromatic hydrocarbons. Stars in the pink regions are a bit older than the rambunctious ones spewing jets, but still relatively young in cosmic terms.

In this image, Spitzer's 3.6- and 4.5-micron data are blue and green, respectively, while WISE's 12-micron data are red. The Spitzer data were taken as part of the mission's Galactic Legacy Infrared Mid-Plane Survey Extraordinaire 360, or Glimpse 360 project, which is pointing the Spitzer Space telescope away from the galactic center to complete a full 360-degree scan of the Milky Way plane.

Image Credit: NASA/JPL-Caltech/University of Wisconsin
Explanation from: https://photojournal.jpl.nasa.gov/catalog/PIA17018

Total Solar Eclipse seen from plane above Pacific Ocean

Plane above Pacific Ocean

August 21, 2017

Image Credit & Copyright: Babak A. Tafreshi

Spiral Galaxy NGC 4565

This image snapped by the NASA/ESA Hubble Space Telescope reveals an exquisitely detailed view of part of the disc of the spiral galaxy NGC 4565. This bright galaxy is one of the most famous examples of an edge-on spiral galaxy, oriented perpendicularly to our line of sight so that we see right into its luminous disc. NGC 4565 has been nicknamed the Needle Galaxy because, when seen in full, it appears as a very narrow streak of light on the sky.

The edgewise view into the Needle Galaxy shown here looks very similar to the view we have from our Solar System into the core of the Milky Way. In both cases ribbons of dust block some of the light coming from the galactic disc. To the lower right, the dust stands in even starker contrast against the copious yellow light from the star-filled central regions. NGC 4565’s core is off camera to the lower right. For a full view of NGC 4565 for comparison’s sake, see this wider field of view from ESO’s Very Large Telescope.

Studying galaxies like NGC 4565 helps astronomers learn more about our home, the Milky Way. At a distance of only about 40 million light-years, NGC 4565 is relatively close by, and being seen edge-on makes it a particularly useful object for comparative study. As spiral galaxies go, NGC 4565 is a whopper — about a third as big again as the Milky Way.

The image was taken with Hubble’s Advanced Camera for Surveys and has a field of view of approximately 3.4 by 3.4 arcminutes.

Image Credit: ESA/Hubble & NASA
Explanation from: https://www.spacetelescope.org/images/potw1228a/

Exoplanet HIP 11915 b

An artist’s impression showing a newly discovered Jupiter twin gas giant orbiting the solar twin star, HIP 11915. The planet is of a very similar mass to Jupiter and orbits at the same distance from its star as Jupiter does from the Sun. This, together with HIP 11915’s Sun-like composition, hints at the possibility of the system of planets orbiting HIP 11915 bearing a resemblance to our own Solar System, with smaller rocky planets orbiting closer to the host star.

Image Credit: ESO/L. Benassi
Explanation from: https://www.eso.org/public/images/eso1529a/

Moon's shadow on Earth seen by DSCOVR Observatory

DSCOVR, 1 million miles from Earth

August 21, 2017

Image Credit: NASA EPIC Team

Spiral Galaxy NGC 1448

Portrayed in this beautiful image is the spiral galaxy NGC 1448, with a prominent disc of young and very bright stars surrounding its small, shining core. Located about 60 million light-years away from the Sun, this galaxy has recently been a prolific factory of supernovae, the dramatic explosions that mark the death of stars : after a first one observed in this galaxy in 1983, two more have been discovered during the past decade.

Visible as a red dot inside the disc, in the upper right part of the image, is the supernova observed in 2003 (SN 2003hn), whereas another one, detected in 2001 (SN 2001el), can be noticed as a tiny blue dot in the central part of the image, just below the galaxy’s core. If captured at the peak of the explosion, a supernova might be as bright as the whole galaxy that hosts it.

This image was obtained using the FORS instrument mounted on one of the 8.2-metre telescopes of ESO’s Very Large Telescope on top of Cerro Paranal, Chile. It combines exposures taken through three filters (B, V, R) on several occasions, between July 2002 and the end of November 2003. The field of view is 7 arcminutes.

Image Credit: ESO
Explanation from: https://www.eso.org/public/images/ngc1448-potw/

The Birth and Death of Stars

In what may look to some like an undersea image of coral and seaweed, a new image from NASA's Spitzer Space Telescope is showing the birth and death of stars. In this view, infrared data from Spitzer are green and blue, while longer-wavelength infrared light from NASA's Wide-field Infrared Survey Explorer (WISE) are red.

The stringy, seaweed-like filaments are the blown out remnants of a star that exploded in a supernova. The billowy clouds seen in pink are sites of massive star formation. Clusters of massive stars can be seen lighting up the clouds, and a bubble carved out from massive stars is seen near the bottom.

This region contains portions of what are known as the W3 and W5 star-forming regions.

In this image, Spitzer's 3.6- and 4.5-micron data are blue and green, respectively, while WISE's 12-micron data are red. The Spitzer data were taken as part of the mission's Galactic Legacy Infrared Mid-Plane Survey Extraordinaire 360, or Glimpse 360 project, which is pointing the Spitzer Space Telescope away from the galactic center to complete a full 360-degree scan of the Milky Way plane.

WISE all-sky observations are boosting Spitzer's imaging capabilities by providing the longer-wavelength infrared coverage the mission lost when it ran out of coolant, as planned, in 2009.

Image Credit: NASA/JPL-Caltech/University of Wisconsin
Explanation from: https://photojournal.jpl.nasa.gov/catalog/PIA17019

Tropical Storm Harvey seen by NOAA’s GOES East satellite

NOAA’s GOES-East satellite provided a visible-light image of Tropical Storm Harvey on Wednesday, August 30, 2017 at 7:30 a.m. EDT (1230 UTC), hours after it made landfall at 4 a.m. CDT just west of Cameron, Louisiana. At the time of the image, the bulk of showers and thunderstorms around Harvey seemed to stretch from the northern to southwestern quadrants of the storm.

Image Credit: NASA/NOAA GOES Project

Star Cluster NGC 3766

This spectacular group of young stars is the open star cluster NGC 3766 in the constellation of Centaurus (The Centaur). Very careful observations of these stars by a group from the Geneva Observatory using the Swiss 1.2-metre Leonhard Euler Telescope at ESO’s La Silla Observatory in Chile have shown that 36 of the stars are of a new and unknown class of variable star.

This image was taken with the MPG/ESO 2.2-metre telescope at the La Silla Observatory.

Image Credit: ESO
Explanation from: https://www.eso.org/public/images/eso1326a/

Galaxy Group NGC 5813

• Chandra data show the supermassive black hole at the center of NGC 5813 has erupted multiple times over 50 million years.

• NGC 5813 is a group of galaxies that is immersed in an enormous reservoir of hot gas.

• Cavities, or bubbles, in the hot gas that Chandra detects gives information about the black hole's eruptions.

• Chandra's observations of NGC 5813 are the longest ever of a galaxy group taken in X-ray light.

Astronomers have used NASA's Chandra X-ray Observatory to show that multiple eruptions from a supermassive black hole over 50 million years have rearranged the cosmic landscape at the center of a group of galaxies.

Scientists discovered this history of black hole eruptions by studying NGC 5813, a group of galaxies about 105 million light years from Earth. These Chandra observations are the longest ever obtained of a galaxy group, lasting for just over a week. The Chandra data are shown in this new composite image where the X-rays from Chandra (purple) have been combined with visible light data (red, green and blue).

Galaxy groups are like their larger cousins, galaxy clusters, but instead of containing hundreds or even thousands of galaxies like clusters do, galaxy groups are typically comprised of 50 or fewer galaxies. Like galaxy clusters, groups of galaxies are enveloped by giant amounts of hot gas that emit X-rays.

The erupting supermassive black hole is located in the central galaxy of NGC 5813. The black hole's spin, coupled with gas spiraling toward the black hole, can produce a rotating, tightly wound vertical tower of magnetic field that flings a large fraction of the inflowing gas away from the vicinity of the black hole in an energetic, high-speed jet.

The researchers were able to determine the length of the black hole's eruptions by studying cavities, or giant bubbles, in the multi-million degree gas in NGC 5813. These cavities are carved out when jets from the supermassive black hole generate shock waves that push the gas outward and create huge holes.

The latest Chandra observations reveal a third pair of cavities in addition to two that were previously found in NGC 5813, representing three distinct eruptions from the central black hole. (Mouse over the image for annotations of the cavities.) This is the highest number of pairs of cavities ever discovered in either a group or a cluster of galaxies. Similar to how a low-density bubble of air will rise to the surface in water, the giant cavities in NGC 5813 become buoyant and move away from the black hole.

To understand more about the black hole's history of eruptions, the researchers studied the details of the three pairs of cavities. They found that the amount of energy required to create the pair of cavities closest to the black hole is lower than the energy that produced the older two pairs. However, the rate of energy production, or power, is about the same for all three pairs. This indicates that the eruption associated with the inner pair of cavities is still occurring.

Each of the three pairs of cavities is associated with a shock front, visible as sharp edges in the X-ray image. These shock fronts, akin to sonic booms for a supersonic plane, heat the gas, preventing most of it from cooling and forming large numbers of new stars.

Close study of the shock fronts reveals that they are actually slightly broadened, or blurred, rather than being very sharp. This may be caused by turbulence in the hot gas. Assuming this is the case, the authors found a turbulent velocity - that is, the average speed of random motions of the gas - of about 160,000 miles per hour (258,000 kilometers per hour). This is consistent with the predictions of theoretical models and estimates based on X-ray observations of the hot gas in other groups and clusters.

Image Credit: X-ray: NASA/CXC/SAO/S.Randall et al., Optical: SDSS
Explanation from: http://chandra.harvard.edu/photo/2015/ngc5813/

Super Typhoon Noru seen from the International Space Station

ISS, Orbit of the Earth

August 1, 2017

Image Credit: NASA

The Trapezium Star Cluster

This image shows a colour composite of near-infrared images of the central regions of the Orion Nebula, obtained on March 14, 2000, with the SOFI instrument at the ESO 3.5-m New Technology Telescope (NTT) at La Silla. Three exposures were made through J- (wavelength 1.25 µm here colour-coded as "blue"), H- (1.65 µm; "green") and Ks-filters (2.16 µm; "red"), respectively. The central group of bright stars is the famous "Trapezium" . The total effective exposure time was 86.4 seconds per band. The sky field measures about 4.9 x 4.9 arcmin 2 (1024 x 1024 pix 2).

Image Credit: ESO
Explanation from: https://www.eso.org/public/images/eso0124a/

Hickson Compact Galaxy Group 59

That galaxies come in very different shapes and sizes is dramatically demonstrated by this striking Hubble image of the Hickson Compact Group 59. Named by astronomer Paul Hickson in 1982, this is the 59th such collection of galaxies in his catalogue of unusually close groups. What makes this image interesting is the variety on display. There are two large spiral galaxies, one face-on with smooth arms and delicate dust tendrils, and one highly inclined, as well as a strangely disorderly galaxy featuring clumps of blue young stars. We can also see many apparently smaller, probably more distant, galaxies visible in the background. Hickson groups display many peculiarities, often emitting in the radio and infrared and featuring active star-forming regions. In addition their galaxies frequently contain Active Galactic Nuclei powered by supermassive black holes, as well large quantities of dark matter.

The NASA/ESA Hubble Space Telescope's Advanced Camera for Surveys, using the Wide Field Channel, captured this image of HCG059 in 2007. The picture was created from images taken through blue, yellow and near-infrared filters (F435W, F606W and F814W). The total exposure times per filter were 57 minutes, 41 minutes and 35 minutes respectively. The field of view is about 3.4 arcminutes across.

Image Credit: ESA/Hubble and NASA
Explanation from: https://www.spacetelescope.org/images/potw1004a/

Tropical Storm Harvey seen from the International Space Station

Astronaut Randy Bresnik took this photo of Tropical Storm Harvey from the International Space Station on August 28 at 1:27 p.m. CDT.

Image Credit: NASA

Planetary System Gliese 581

After more than four years of observations using the most successful low-mass exoplanet hunter in the world, the HARPS spectrograph attached to the 3.6-metre ESO telescope at La Silla, Chile, astronomers have discovered in this system the lightest exoplanet found so far: Gliese 581e (foreground) is only about twice the mass of our Earth. The Gliese 581 planetary system now has four known planets, with masses of about 1.9 (planet e, left in the foreground), 16 (planet b, nearest to the star), 5 (planet c, centre), and 7 Earth-masses (planet d, with the bluish colour). The planet furthest out, Gliese 581d, orbits its host star in 66.8 days, while Gliese 581 e completes its orbit in 3.15 days.

Image Credit: ESO/L. Calçada
Explanation from: https://www.eso.org/public/images/eso0915a/

Saturn's north pole

These turbulent clouds are on top of the world at Saturn. NASA's Cassini spacecraft captured this view of Saturn's north pole on April 26, 2017 - the day it began its Grand Finale -- as it approached the planet for its first daring dive through the gap between the planet and its rings.

Although the pole is still bathed in sunlight at present, northern summer solstice on Saturn occurred on May 24, 2017, bringing the maximum solar illumination to the north polar region. Now the Sun begins its slow descent in the northern sky, which eventually will plunge the north pole into Earth-years of darkness. Cassini's long mission at Saturn enabled the spacecraft to see the Sun rise over the north, revealing that region in great detail for the first time.

This view looks toward the sunlit side of the rings from about 44 degrees above the ring plane. The image was taken with the Cassini spacecraft wide-angle camera using a spectral filter which preferentially admits wavelengths of near-infrared light centered at 752 nanometers.

The view was obtained at a distance of approximately 166,000 miles (267,000 kilometers) from Saturn. Image scale is about 10 miles (16 kilometers) per pixel.

Image Credit: NASA/JPL-Caltech/Space Science Institute
Explanation from: https://photojournal.jpl.nasa.gov/catalog/PIA21343

Lunar Eclipse seen from Garching

This image was taken by ESO Photo Ambassador Petr Horálek, and shows a partial lunar eclipse near its peak, as visible from the roof of the ESO Headquarters in Garching, Germany on 7 August 2017.

The entire Moon is turned red by its light scattering through the Earth’s atmosphere. Meanwhile, the bottom right part of the full Moon blends into the sky having entered the umbra of the Earth’s shadow.

Image Credit: ESO/P. Horálek
Explanation from: https://www.eso.org/public/images/potw1733b/

Neptune seen from Saturn by Cassini spacecraft

On August 25, 1989, NASA's Voyager 2 made its historic flyby of Neptune and that planet's largest moon Triton. The Cassini mission is publishing this image to celebrate the anniversary of that event.

Neptune appears in this natural color composite as a pale blue disk (similar to Cassini's image of Uranus from 2014), just below and to the right of image center. Most of the faint specks in the image are background stars, although some are likely cosmic rays (charged particles that strike the camera detector).

A cropped and magnified version is provided in monochrome with Triton visible as a point of light above and to the left of Neptune.

In imaging Neptune, Cassini's solar system family portrait-taking is complete. The mission's planetary photojournal includes all of the major planets except Mercury, which is too close to the Sun to be imaged, as well as dwarf planet Pluto.

This view was acquired by the Cassini narrow-angle camera on Aug. 10, 2017, at a distance of approximately 2.72 billion miles (4.38 billion kilometers) from Neptune. Red, blue and green filter images were combined to create the natural color image.

Image Credit: NASA/JPL-Caltech/Space Science Institute
Explanation from: https://photojournal.jpl.nasa.gov/catalog/PIA21629

Interacting Galaxies MCG+01-38-004 • MCG+01-38-005

Phenomena across the Universe emit radiation spanning the entire electromagnetic spectrum — from high-energy gamma rays, which stream out from the most energetic events in the cosmos, to lower-energy microwaves and radio waves.

Microwaves, the very same radiation that can heat up your dinner, are produced by a multitude of astrophysical sources, including strong emitters known as masers (microwave lasers), even stronger emitters with the somewhat villainous name of megamasers, and the centres of some galaxies. Especially intense and luminous galactic centres are known as active galactic nuclei. They are in turn thought to be driven by the presence of supermassive black holes, which drag surrounding material inwards and spit out bright jets and radiation as they do so.

The two galaxies shown here, imaged by the NASA/ESA Hubble Space Telescope, are named MCG+01-38-004 (the upper, red-tinted one) and MCG+01-38-005 (the lower, blue-tinted one). MCG+01-38-005 is a special kind of megamaser; the galaxy’s active galactic nucleus pumps out huge amounts of energy, which stimulates clouds of surrounding water. Water’s constituent atoms of hydrogen and oxygen are able to absorb some of this energy and re-emit it at specific wavelengths, one of which falls within the microwave regime. MCG+01-38-005 is thus known as a water megamaser!

Astronomers can use such objects to probe the fundamental properties of the Universe. The microwave emissions from MCG+01-38-005 were used to calculate a refined value for the Hubble constant, a measure of how fast the Universe is expanding. This constant is named after the astronomer whose observations were responsible for the discovery of the expanding Universe and after whom the Hubble Space Telescope was named, Edwin Hubble.

Image Credit: ESA/Hubble & NASA
Explanation from: https://www.spacetelescope.org/images/potw1735a/