Sextans A

A small galaxy, called Sextans A, is shown here in a multi-wavelength mosaic captured by the European Space Agency's Herschel mission, in which NASA is a partner, along with NASA's Galaxy Evolution Explorer (GALEX) and the National Radio Astronomy Observatory's Jansky Very Large Array observatory near Socorro, New Mexico. The galaxy is located 4.5 million light-years from Earth in the Sextans constellation.

The environment in this galaxy is similar to that of our infant universe because it lacks in heavy metals, or elements heavier than hydrogen and helium. Heavy metals act in some ways like fertilizers for stars, helping them form and grow. Scientists study galaxies like Sextans A to learn how stars still manage to slowly bloom under these poor-growing conditions. The research provides a better understanding of how the very first stars in our universe came to be.

In this image, the purple shows gas; blue shows young stars and the orange and yellow dots are newly formed stars heating up dust.

Image credit: ESA/NASA/JPL-Caltech/NRAO

Saturn's North Polar Hexagon

The giant planet Saturn is mostly a gigantic ball of rotating gas, completely unlike our solid home planet. But Earth and Saturn do have something in common: weather, although the gas giant is home to some of the most bizarre weather in our Solar System, such as the swirling storm shown in this Cassini view.

Known as “the hexagon”, this weather feature is an intense, six-sided jet stream at Saturn’s north pole. Spanning some 30,000 km across, it hosts howling 320 km/h winds that spiral around a massive storm rotating anticlockwise at the heart of the region.

Numerous small vortices rotate in the opposite direction to the central storm and are dragged around with the jet stream, creating a terrifically turbulent region. While a hurricane on Earth may last a week or more, the hexagon has been raging for decades, and shows no signs of letting up.

This false-color image of the hexagon was made using ultraviolet, visible and infrared filters to highlight different regions.

The dark center of the image shows the large central storm and its eye, which is up to 50 times bigger than a terrestrial hurricane eye. The small vortices show up as pink-red clumps. Towards the lower right of the frame is a white-tinted oval storm that is bigger than any of the others — this is the largest of the vortices at some 3500 km across, twice the size of the largest hurricane ever recorded on Earth.

The darker blue region within the hexagon is filled with small haze particles, whereas the paler blue region is dominated by larger particles. This divide is caused by the hexagonal jet stream acting as a shepherding barrier — large particles cannot enter the hexagon from the outside.

These large particles are created when sunlight shines onto Saturn’s atmosphere, something that only started relatively recently in the northern hemisphere with the beginning of northern spring in August 2009.

Cassini will continue to track changes in the hexagon, monitoring its contents, shape and behavior as summer reaches Saturn’s northern hemisphere in 2017.

An animated version is available here.

Image credit: NASA/JPL-Caltech/SSI/Hampton University

Comet 067P Churyumov-Gerasimenko Darker Than Charcoal

A NASA instrument aboard the European Space Agency’s (ESA's) Rosetta orbiter has successfully made its first delivery of science data from comet 67P/Churyumov-Gerasimenko.

The instrument, named Alice, began mapping the comet’s surface last month, recording the first far-ultraviolet light spectra of the comet’s surface. From the data, the Alice team discovered the comet is unusually dark -- darker than charcoal-black -- when viewed in ultraviolet wavelengths. Alice also detected both hydrogen and oxygen in the comet’s coma, or atmosphere.

Rosetta scientists also discovered the comet’s surface so far shows no large water-ice patches. The team expected to see ice patches on the comet’s surface because it is too far away for the sun’s warmth to turn its water into vapor.

"We’re a bit surprised at just how unreflective the comet’s surface is and how little evidence of exposed water-ice it shows," said Alan Stern, Alice principal investigator at the Southwest Research Institute in Boulder, Colorado.

Alice is probing the origin, composition and workings of comet 67P/Churyumov-Gerasimenko, to gather sensitive, high-resolution insights that cannot be obtained by either ground-based or Earth-orbiting observation. It has more than 1,000 times the data-gathering capability of instruments flown a generation ago, yet it weighs less than nine pounds (four kilograms) and draws just four watts of power. The instrument is one of two full instruments on board Rosetta that are funded by NASA. The agency also provided portions of two other instrument suites.

Other U.S. contributions aboard the spacecraft are the Microwave Instrument for Rosetta Orbiter (MIRO), the Ion and Electron Sensor (IES), part of the Rosetta Plasma Consortium Suite, and the Double Focusing Mass Spectrometer (DFMS) electronics package for the Rosetta Orbiter Spectrometer for Ion Neutral Analysis (ROSINA). They are part of a suite of 11 total science instruments aboard Rosetta.

MIRO is designed to provide data on how gas and dust leave the surface of the nucleus to form the coma and tail that gives comets their intrinsic beauty. IES is part of a suite of five instruments to analyze the plasma environment of the comet, particularly the coma.

To obtain the orbital velocity necessary to reach its comet target, the Rosetta spacecraft took advantage of four gravity assists (three from Earth, one from Mars) and an almost three-year period of deep space hibernation, waking up in January 2014 in time to prepare for its rendezvous with 67P/Churyumov-Gerasimenko.

Rosetta also carries a lander, Philae, which will drop to the comet’s surface in November 2014.

The comet observations will help scientists learn more about the origin and evolution of our solar system and the role comets may have played in providing Earth with water, and perhaps even life.

Image credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA; Text credit: Science@NASA

Note: For more information, see NASA Instrument on Rosetta: First Science Results and Rosetta’s Imaging and Spectroscopy Instruments.

NGC 3081

Taking center stage in this new NASA/ESA Hubble Space Telescope image is a galaxy known as NGC 3081, set against an assortment of glittering galaxies in the distance. Located in the constellation of Hydra (The Sea Serpent), NGC 3081 is located over 86 million light-years from us. It is known as a type II Seyfert galaxy, characterized by its dazzling nucleus.

NGC 3081 is seen here nearly face-on. Compared to other spiral galaxies, it looks a little different. The galaxy's barred spiral center is surrounded by a bright loop known as a resonance ring. This ring is full of bright clusters and bursts of new star formation, and frames the supermassive black hole thought to be lurking within NGC 3081 — which glows brightly as it hungrily gobbles up infalling material.

These rings form in particular locations known as resonances, where gravitational effects throughout a galaxy cause gas to pile up and accumulate in certain positions. These can be caused by the presence of a "bar" within the galaxy, as with NGC 3081, or by interactions with other nearby objects. It is not unusual for rings like this to be seen in barred galaxies, as the bars are very effective at gathering gas into these resonance regions, causing pile-ups which lead to active and very well-organized star formation.

Hubble snapped this magnificent face-on image of the galaxy using the Wide Field Planetary Camera 2. This image is made up of a combination of ultraviolet, optical, and infrared observations, allowing distinctive features of the galaxy to be observed across a wide range of wavelengths.

Image credit: ESA/Hubble & NASA

Hubble Ultra Deep Field 2014

Astronomers using the Hubble Space Telescope have captured the most comprehensive picture ever assembled of the evolving Universe – and one of the most colorful. The study is called the Ultraviolet Coverage of the Hubble Ultra Deep Field (UVUDF) project.

Image credit: NASA, ESA, H. Teplitz and M. Rafelski (IPAC/Caltech), A. Koekemoer (STScI), R. Windhorst (Arizona State University), and Z. Levay (STScI)

Note: For more information, see Hubble Unveils a Colorful View of the Universe.

Auroras on Saturn

Astronomers using the NASA/ESA Hubble Space Telescope have captured new images of the dancing auroral lights at Saturn’s north pole. Taken in April and May 2013 from Hubble’s perspective in orbit around Earth, these observations provide a detailed look at previously unseen dynamics in the choreography of the auroral glow.

The ultraviolet images, taken by Hubble’s super-sensitive Advanced Camera for Surveys, capture moments when Saturn’s magnetic field is affected by bursts of particles streaming from the Sun.

Saturn’s magnetosphere – the vast magnetic ‘bubble’ that surrounds the planet – is compressed on the Sunward side of the planet, and streams out into a long ‘magnetotail’ on the nightside.

It appears that when particles from the Sun hit Saturn, the magnetotail collapses and later reconfigures itself, an event that is reflected in the dynamics of its auroras.

Saturn was caught during a very dynamic light show – some of the bursts of light seen shooting around Saturn’s polar regions traveled more than three times faster than the speed of the gas giant’s roughly 10-hour rotation period!

The new observations were taken as part of a three-year Hubble observing campaign, and are presented in a paper published in the journal Geophysical Research Letters. The images complement those taken by the international Cassini spacecraft orbiting Saturn.

Image credit: NASA/ESA, Acknowledgement: J. Nichols (University of Leicester)

Saturn's C and B Rings in Ultraviolet Light

This colorful cosmic rainbow portrays a section of Saturn’s beautiful rings, four centuries after they were discovered by Galileo Galilei.

Saturn’s rings were first observed in 1610. Despite using his newly created telescope, Galileo was confounded by what he saw: he referred to the peculiar shapes surrounding the planet as “Saturn’s children”. Only later did Christiaan Huygens propose that the mysterious shapes were actually rings orbiting the planet. These were named in the order in which they were discovered, using the first seven letters of the alphabet: the D-ring is closest to the planet, followed by C, B, A, F, G and E.

The data for this image, which shows the portion of the C-ring closest to Saturn on the left, with the B-ring beginning just right of center, were acquired by Cassini’s Ultraviolet Imaging Spectrograph, or UVIS, as the spacecraft entered into orbit around Saturn on 30 June 2004.

UVIS, as its name suggests, carries out observations in ultraviolet wavelengths. During the Saturn orbit insertion maneuver, when Cassini flew closest to the rings, UVIS could resolve features up to 97 km across. The region shown in this image spans about 10,000 km.

The variation in the color of the rings arises from the differences in their composition. Turquoise-hued rings contain particles of nearly pure water ice, whereas reddish rings contain ice particles with more contaminants.

Saturn’s prominent and complex ensemble of rings is the best studied in the Solar System, but it is still not known how the rings formed. One suggestion is that they formed at the same time as the planet and that they are as old as the Solar System. Another idea is that they formed when icy material was pulled from another body into Saturn’s gravitational field, in which case the rings could be younger than the planet.

One thing is sure: as Cassini searches for answers it is providing amazing images of these rainbow rings.

The Cassini–Huygens mission is a cooperative project of NASA, ESA and Italy’s ASI space agency.

This image was first published at the NASA Cassini website, in 2004.

Image credit: NASA/JPL/University of Colorado

Solar Cycle 23

It took 10 years to create this image of our changing Sun. Taken from space by the Solar and Heliospheric Observatory (SOHO), it shows a dramatically different picture than the one we receive on Earth.

From Earth’s surface, we are treated to a biased view. Every day our world is bathed in the Sun’s light and heat, and at these visible and infrared wavelengths our luminary shines to within a fraction of a percent of the same energy every day.

At ultraviolet and X-ray wavelengths, this is not true. Launched in 1995, SOHO has been continuously monitoring the Sun since then, in part to study this variation. Back in 2006, one image for each year of the mission until then was chosen and displayed in this montage.

The bright parts of these images correspond to gas in the Sun’s atmosphere at a temperature of about 2 million degrees Celsius.

Unlike visible light, the intensity of the ultraviolet radiation from the Sun varies greatly. This variation becomes more pronounced the shorter the wavelength, especially in the X-ray region of the spectrum. This is governed by solar activity, which runs in an approximately 11-year cycle. It is linked to the generation of the Sun’s magnetic field although our precise understanding of this mechanism remains elusive.

The waxing and waning of cycle-23, counted since 1755 when systematic record-taking began, can be seen clearly in this image. At its peak in 2001, the Sun was a maelstrom of activity, releasing about 10 times more ultraviolet light than at the minimum periods that can be seen in 1996 and 2006.

Now in cycle-24, the Sun is again at a peak of activity, although it is milder than that of 2001.

This image was originally published at the Solar and Heliospheric Observatory website.

Image credit: SOHO (ESA & NASA)

Venus Glory

False color composite of a ‘glory’ seen on Venus on 24 July 2011. The image is composed of three images at ultraviolet, visible, and near-infrared wavelengths from the Venus Monitoring Camera. The images were taken 10 seconds apart and, due to the motion of the spacecraft, do not overlap perfectly. The glory is 1200 km across, as seen from the spacecraft, 6000 km away.

Image credit: (top) ESA/MPS/DLR/IDA; (bottom) C. Wilson/P. Laven

Note: For more information, see Venus Glory.

ESO 137-001

This new Hubble image shows spiral galaxy ESO 137-001, framed against a bright background as it moves through the heart of galaxy cluster Abell 3627.

This image not only captures the galaxy and its backdrop in stunning detail, but also something more dramatic – intense blue streaks streaming outwards from the galaxy, seen shining brightly in ultraviolet light.

These streaks are in fact hot, wispy streams of gas that are being torn away from the galaxy by its surroundings as it moves through space. This violent galactic disrobing is due to a process known as ram pressure stripping – a drag force felt by an object moving through a fluid.

Image credit: NASA, ESA. Acknowledgements: Ming Sun (UAH), and Serge Meunier

Note: For more information, see Spiral Galaxy Spills Blood and Guts, and ESO 137-001: Life Is Too Fast, Too Furious for This Runaway Galaxy. The "intense blue streaks" mentioned in the above article are much more apparent in the composite image produced by the Hubble Space Telescope and Chandra X-Ray Observatory; click on the second link to see that image.

Saturn's Auroras

Ultraviolet and infrared images from NASA's Cassini spacecraft and Hubble Space Telescope show active and quiet auroras at Saturn's north and south poles.

Saturn's auroras glow when energetic electrons dive into the planet's atmosphere and collide with hydrogen molecules. Sometimes a blast of fast solar wind, composed of mostly electrons and protons, creates an active aurora at Saturn, as occurred on April 5 and May 20, 2013.

The first set of images, as seen in the ultraviolet part of the spectrum by Hubble, shows an active aurora dancing around Saturn's north pole on April 5. The movie then shows a relatively quiet time between April 19 to 22 and between May 18 and 19. The aurora flares up again in Hubble images from May 20. This version, shown in false-color, has been processed to show the auroras more clearly.

A second set of ultraviolet images shows a closer view of an active north polar aurora in white. This set comes from Cassini ultraviolet imaging spectrograph observations on May 20 and 21.

The last set of images, in the infrared, shows a quiet southern aurora (in green) in observations from Cassini's visual and infrared mapping spectrometer on May 17. Saturn's inner heat glows in red, with dark areas showing where high clouds block the heat.

Video credit: NASA/JPL-Caltech/University of Colorado/Central Arizona College and NASA/ESA/University of Leicester and NASA/JPL-Caltech/University of Arizona/Lancaster University

Note: For more information, see PIA17668: Saturn's Colorful Aurora and NASA Spacecraft Get a 360-Degree View of Saturn's Auroras.

Proba-2 Sees Three Partial Solar Eclipses

The total solar eclipse of 13-14 November 2012 was only visible to ground-based observers situated in northern Australia, while ESA's Sun-watching satellite Proba-2 enjoyed three partial eclipses from its viewpoint in space. The constant change in viewing angle of Proba-2 as it orbits the Earth meant that the satellite passed through the Moon’s shadow a total of three times during the eclipse event. The video was produced from images taken by Proba-2’s SWAP imager, which snaps the Sun in ultraviolet light to reveal stormy active regions on the solar disc.

The apparent noise in the movie results from high energy particles hitting Proba-2's electronics as the spacecraft passes through the South Atlantic Anomaly. The dimming in the movie is an effect as part of the satellite's orbit passes through the shadow of the Earth.

Read full article here: http://www.esa.int/esaSC/SEMFYC72Q8H_index_0.html

Video credit: ESA

Saturn's North Polar Hexagon

This colorful view from NASA's Cassini mission is the highest-resolution view of the unique six-sided jet stream at Saturn's north pole known as "the hexagon." This movie, made from images obtained by Cassini's imaging cameras, is the first to show the hexagon in color filters, and the first movie to show a complete view from the north pole down to about 70 degrees north latitude.

Scientists can see the motion of a wide variety of cloud structures that reside within the hexagon in this movie. There is a massive hurricane tightly centered on the north pole, with an eye about 50 times larger than the average hurricane eye on Earth. (More information about that Saturn hurricane is at PIA14947.) Numerous small vortices are also present, which appear as reddish ovals. Some of these vortices spin clockwise while the hexagon and hurricane spin counterclockwise. Some of those smaller features are swept along with the jet stream of the hexagon, as if on a racetrack. The biggest of these vortices, seen near the lower right corner of the hexagon and appearing whitish, spans about 2,200 miles (3,500 kilometers), approximately twice the size of the largest hurricane on Earth.

The differences in this version of the movie, in which different wavelengths of light from ultraviolet to visible to infrared have been assigned colors, show a distinct contrast between the types of atmospheric particles inside and outside the hexagon. Inside the hexagon there are fewer large haze particles and a concentration of small haze particles, while outside the hexagon, the opposite is true. The jet stream that makes up the hexagon seems to act like a barrier, which results in something like the "ozone hole" in the Antarctic.

This movie shows a view from directly over the north pole, keeping up with the rotation of the planet so that all the motion seen on the screen is the motion of the hexagonal jet stream or the storms inside of it, without any added motion from the spinning of the planet itself. The original images were re-projected to show this polar view.

High-resolution views of the hexagon have only recently become possible because of the changing of the seasons at Saturn and changes in the Cassini spacecraft's orbit. The north pole was dark when Cassini first arrived in July 2004. The sun really only began to illuminate the entire interior of the hexagon in August 2009, with the start of northern spring. In late 2012, Cassini began making swings over Saturn's poles, giving it better views of the hexagon.

The eight frames of the movie were captured over 10 hours on December 10, 2012. Each of the eight frames consists of 16 map-projected images (four per color filter, and four filters per frame) so the movie combines data from 128 images total.

In this color scheme, scientists assigned red to the 0.750-micron part of the light spectrum (near infrared). This part of the spectrum penetrates the high-altitude haze layer to sense the top of tropospheric cloud deck. They assigned green to the 0.727-micron part of the light spectrum that senses the upper tropospheric haze (a near-infrared wavelength corresponding to a methane absorption band). They assigned blue to the sum of blue and ultraviolet broadband filters -- combined, this blue channel covers between 0.400 and 0.500 microns (covering very near ultraviolet to blue in visible light). This part of the spectrum is sensitive to small aerosols.

To human eyes, the hexagon and north pole would appear in tones of gold and blue. See PIA14945 for a still image of the area in natural color.

Video credit: NASA/JPL-Caltech/SSI/Hampton University

Note: For more information, see PIA17653: Hexagon in Silhouette, PIA17654: Looking Down on the Hexagon in Infrared, and NASA's Cassini Spacecraft Obtains Best Views of Saturn Hexagon.

Himiko Galaxies

The big blob-like structure shown here, named Himiko after the legendary ancient queen of Japan, turns out to be three galaxies thought to be in the process of merging into one. In this image, infrared data from NASA's Spitzer Space Telescope are red; visible data from NASA's Hubble Space Telescope are green; and ultraviolet data from Japan's Subaru telescope on Mauna Kea, Hawaii are blue.

Himiko is located nearly 13 billion light-years from Earth, dating back to a time when galaxies were first forming.

Image credit: NASA/JPL-Caltech/STScI/NAOJ/Subaru

Note: For more information, see Infant Galaxies Merge Near 'Cosmic Dawn'.

Messier 15

This cluster of stars is known as Messier 15, and is located some 35,000 light-years away in the constellation of Pegasus (The Winged Horse). It is one of the oldest globular clusters known, with an age of around 12 billion years.

Both very hot blue stars and cooler golden stars can be seen swarming together in the image, becoming more concentrated towards the cluster's bright center. Messier 15 is one of the densest globular clusters known, with most of its mass concentrated at its core. As well as stars, Messier 15 was the first cluster known to host a planetary nebula, and it has been found to have a rare type of black hole at its center.

This new image is made up of observations from Hubble's Wide Field Camera 3 and Advanced Camera for Surveys in the ultraviolet, infrared, and optical parts of the spectrum.

Photo credit: NASA, ESA

Note: For more information, see Hubble Views an Old and Mysterious Cluster.

Proba-2's View of the Hybrid Eclipse

Three partial solar eclipses are seen in this movie from ESA’s Proba-2 Sun-watching satellite as it dipped in and out of the Moon’s shadow during yesterday’s ‘hybrid’ solar eclipse.

A hybrid eclipse comprises a total solar eclipse and an ‘annular eclipse’, depending on an observer’s viewing location on Earth.

During a total solar eclipse, the Moon moves in front of the Sun as seen from Earth, their alignment and separation such that the much closer Moon appears large enough to block out the light from the much more distant Sun.

But from some locations, the apparent size of the Moon is slightly smaller than that of the Sun, leaving a bright ring around the dark disc of the Moon.

Meanwhile, from its vantage point in Earth orbit, Proba-2 saw several partial eclipses.

Proba-2 orbits Earth about 14.5 times per day, dipping in and out of the Moon’s shadow around the time of a solar eclipse.

The video was produced from images taken by Proba-2’s SWAP imager, which snaps the Sun in ultraviolet light. Stormy active regions on the Sun’s face are revealed, including sunspots, the roots of some large solar flares and ‘coronal mass ejections’ that are occasionally directed towards Earth.

Video credit: ESA

NGC 3377

New evidence from NASA's Wide-field Infrared Survey Explorer (WISE) and Galaxy Evolution Explorer (GALEX) missions provide support for the "inside-out" theory of galaxy evolution, which holds that star formation starts at the core of the galaxy and spreads outward.

In this image of a galaxy called NGC 3377, infrared light from WISE is colored red, and ultraviolet light from GALEX is green and blue. The center of the galaxy appears white, where all three wavelengths of light are present and add up. The outside of the galaxy is mostly ultraviolet light, and thus contains more blue and green. The dots in the picture are stars located in the foreground.

NGC 3377 is located 31 million light-years away in the constellation Leo. It is an older galaxy, having already exhausted its stellar fuel supply. The outer regions, while containing more young stars than the core, are bright in ultraviolet light due to a small population of older, extremely hot stars.

WISE and GALEX are both no longer operating, but scientists continue to access their bounties of data through public archives.

Image credit: NASA/JPL-Caltech

Note: For more information, see Galaxy Growth Examined Like Rings of a Tree.

The Sun in Extreme Ultraviolet Light

Several large, active regions on the Sun burst out with about 20 eruptions between 25 and 28 October 2013. Some were flares; some were coronal mass ejections, and at least one was a prominence eruption.

This is an image of the Sun in extreme UV light from the Solar Dynamic Observatory superimposed on a visible-light image of the solar corona obtained with SOHO's C2 coronagraph. The still was taken on 26 October.

The Sun is about at its maximum level of activity in its 11-year solar cycle, so stormy stretches like this one are to be expected.

Image credit: ESA/NASA

Coronal Mass Ejection Intensity Map

A coronal mass ejection observed by the ESA/NASA SOHO space mission on 4 January 2002 has been colored to indicate the intensity of the matter being ejected by the Sun. White represents the greatest intensity, red/orange somewhat less, and blue the least.

An extreme-ultraviolet image of the Sun captured by SOHO’s EIT (Extreme ultraviolet Imaging Telescope) instrument is superimposed on the image. The shaded blue disc surrounding the Sun at the center is a mask in SOHO’s LASCO instrument that blots out direct sunlight to allow study of the details in the Sun’s corona.

Image credit: SOHO (ESA/NASA)/S. Hill

IBEX Maps the Sun's Heliotail

Like a comet, the solar system has a tail. NASA's Interstellar Boundary Explorer (IBEX) has for the first time mapped out the structure of this tail, which is shaped like a four-leaf clover.

Scientists describe the tail, called the heliotail, based on the first three years of IBEX imagery in a paper published in the July 10 edition of the Astrophysical Journal.

While telescopes have spotted such tails around other stars, it has been difficult to see whether our star produced one. The particles found in the tail -- and throughout the entire heliosphere, the region of space influenced by our sun -- do not shine, so they cannot be seen with conventional instruments.

"By examining the neutral atoms, IBEX has made the first observations of the heliotail," said David McComas, IBEX principal investigator at Southwest Research Institute in San Antonio, Texas, and the paper's lead author. "Many models have suggested the heliotail might look like this or like that, but we have had no observations. We always drew pictures where the tail of the solar system just trailed off the page, since we couldn't even speculate about what it really looked like."

Other stars show tails that trail behind them like a comet’s tail; [pictured above is the star Mira and its tail, shown in ultraviolet light and imaged by the GALEX satellite]. Scientists used NASA’s Interstellar Boundary Explorer to confirm that our solar system has one too.

IBEX measures the neutral particles created by collisions at the solar system's boundaries. This technique, called energetic neutral atom imaging, relies on the fact that the paths of neutral particles are not affected by the solar magnetic field. Instead, the particles travel in a straight line from collision to IBEX. Consequently, observing where the neutral particles came from describes what is going on in these distant regions.

"Since first light in 2008, the IBEX mission team has amazed us with its discoveries at the interstellar boundary, including a previously unknown ribbon of energetic neutral particles stretching across it," said Arik Posner, NASA's IBEX program scientist in Washington. "The new IBEX image of the heliotail fills in a previously blank area on the map. We are first-hand witnesses of rapid progress in heliophysics science."

By combining observations from the first three years of IBEX imagery, the team showed a tail with a combination of fast and slow moving particles. There are two lobes of slower particles on the sides and faster particles above and below. This four-leaf clover shape can be attributed to the fact that the sun has been sending out fast solar wind near its poles and slower wind near its equator for the last few years. This is a common pattern in the most recent phase of the sun's 11-year activity cycle.

The clover shape does not align perfectly with the solar system, however. The entire shape is rotated slightly, indicating that as it moves further away from the sun and its magnetic influence, the charged particles begin to be nudged into a new orientation, aligning with the magnetic fields from the local galaxy.

Scientists do not know how long the tail is, but think that it eventually fades away and becomes indistinguishable from the rest of interstellar space. Scientists are testing their current computer simulations of the solar system against the new observations to improve our understanding of the comet-like tail streaming out behind us.

Video credit: NASA; image credit: NASA/JPL-Caltech/GALEX