Cosmic Pearls

Two decades ago, astronomers spotted one of the brightest exploding stars in more than 400 years.

Since that first sighting, the doomed star, called Supernova 1987A, has continued to fascinate astronomers with its spectacular light show. NASA's Hubble Space Telescope is one of many observatories that has been monitoring the blast's aftermath. The supernova is located 163,000 light-years away in the Large Magellanic Cloud.

This image shows the entire region surrounding the supernova, the most prominent feature of which is a ring with dozens of bright spots, shining like cosmic pearls. Unleashed by the stellar blast, this material is slamming into regions along the ring's inner regions, heating them up, and causing them to glow. The ring, about a light-year across, was likely shed by the star about 20,000 years before it exploded.

This image was taken in December 2006 with Hubble's Advanced Camera for Surveys.

Trifid Nebula

The Trifid Nebula, aka M20, is easy to find with a small telescope and a well-known stop in the nebula rich constellation Sagittarius. But where visible light pictures show the nebula divided into three parts by dark, obscuring dust lanes, this penetrating infrared image reveals filaments of luminous gas and newborn stars.

This spectacular false-color view is courtesy of the Spitzer Space Telescope. Astronomers have used the Spitzer infrared image data to count newborn and embryonic stars that otherwise lie hidden in the natal dust and glowing clouds of this intriguing stellar nursery.

Omega Nebula: Close-Up of a Stellar Nursery

Sculpted by stellar winds and radiation, these fantastic, undulating shapes lie within the stellar nursery known as M17, the Omega Nebula, some 5,500 light-years away in the nebula-rich constellation Sagittarius. The lumpy features in the dense cold gas and dust are illuminated by stars off the upper left of the image and may themselves represent sites of future star formation. Colors in the fog of surrounding hotter material indicate M17's chemical make up. The predominately green glow corresponds to abundant hydrogen, with trace sulfur and oxygen atoms contributing red and blue hues. The picture spans about 3 light-years.

Windblown

A fast and powerful wind from a hot young star created this stunning bubble-shaped nebula, poised on the end of a bright filament of hydrogen gas. Cataloged as N44F, the cosmic windblown bubble is seen at the left of this Hubble Space Telescope image. N44F lies along the northern outskirts of the N44 complex of emission nebulae in the Large Magellanic Cloud, a mere 160,000 light-years away.

The bright, blue, hot star itself is just below the center of the bubble. Peering into the bubble's interior, the Hubble image reveals dramatic structures, including pillars of dust, aligned toward N44F's hot central star. Reminiscent of dust pillars in stellar nurseries within our Milky Way galaxy, they likely contain young stars at their tips. Expanding into the surrounding gas and dust at about 12 kilometers, or 7.5 miles, per second, N44F is around 35 light-years across.

Io's Colorful Face

Io is a colorful place. The closest large moon of Jupiter, Io has the most volcanic activity of any moon in the solar system with its surface being completely buried in volcanic lava every few thousand years. The black and red material corresponds to the most recent volcanic eruptions and is probably no more than a few years old. This image by the automated spacecraft Galileo highlights the side of Io that always faces away from Jupiter. In this image, colors have been adjusted to enhance contrast, but are based on real composite infrared, green and violet-light images.

Eskimo Nebula

In 1787, astronomer William Herschel discovered the Eskimo Nebula, which from the ground resembles a person's head surrounded by a parka hood. In 2000, the Hubble Space Telescope imaged the nebula that displays gas clouds so complex they are not fully understood. The Eskimo Nebula is clearly a planetary nebula, and the gas seen above composed the outer layers of a sun-like star only 10,000 years ago. The inner filaments visible above are being ejected by strong wind of particles from the central star. The outer disk contains unusual light-year long orange filaments.

Bow Tie Nebula

Planetary nebula NGC 2440 has an intriguing bow-tie shape in this stunning view from space. The nebula is composed of material cast off by a dying sun-like star as it enters its white dwarf phase of evolution. Details of remarkably complex structures are revealed within NGC 2440, including dense ridges of material swept back from the nebula's central star.

The star itself is one of the hottest known, with a surface temperature of about 200,000 kelvins. About 4,000 light-years from planet Earth toward the nautical constellation Puppis, the nebula spans more than a light-year and is energized by ultraviolet light from the central star. The false-color image was recorded using the Hubble's Wide-Field Planetary Camera 2 (WFPC2), demonstrating still impressive imaging capabilities following the failure of the Advanced Camera for Surveys.

Star Crossed

How massive can a star be? Estimates made from distance, brightness and standard solar models have accorded one star in the open cluster Pismis 24 over 200 times the mass of our sun. This star is the brightest object located just to the right of the gas front in the above image.

Close inspection of images taken recently with the Hubble Space Telescope, however, have shown that Pismis 24-1 derives its brilliant luminosity not from a single star but from three at least. Component stars would still remain near 100 solar masses, making them among the more massive stars currently on record. Toward the image left, stars are still forming in the associated emission nebula NGC 6357, including several that appear to be breaking out and illuminating a spectacular cocoon.

Sun Storm!

The sun-orbiting SOHO spacecraft has imaged many erupting filaments lifting off the active solar surface and blasting enormous bubbles of magnetic plasma into space. This image shows the sun in ultraviolet light, while the field of view extends over 2 million kilometers, or 1.243 million miles, from the solar surface.

While hints of these explosive sun storms, called coronal mass ejections or CMEs, were discovered by spacecraft in the early 1970s, this dramatic image is part of a detailed record of this CME's development from the presently operating SOHO spacecraft. At a minimum, solar activity cycle CMEs occur about once a week, with maximum rates of two or more per day. Strong CMEs may profoundly influence space weather and those directed toward our planet can have serious effects.

The Prometheus Plume

What's happening on Jupiter's moon Io? Two sulfurous eruptions are visible on Jupiter's volcanic moon Io in this color composite image from the robotic Galileo spacecraft that orbited Jupiter from 1995 to 2003. At the image top, over Io's limb, a bluish plume rises about 140 kilometers above the surface of a volcanic caldera known as Pillan Patera.

In the image middle, near the night/day shadow line, the ring shaped Prometheus plume is seen rising about 75 kilometers, or about 46 miles, above Io while casting a shadow below the volcanic vent. Named for the Greek god who gave mortals fire, the Prometheus plume is visible in every image ever made of the region dating back to the Voyager flybys of 1979, presenting the possibility that this plume has been continuously active for at least 18 years. The above digitally sharpened image was originally recorded on June 28, 1997 from a distance of about 600,000 kilometers, or 373,000 miles.

Detailing the Big Picture

This image from NASA's Hubble Space Telescope shows the diverse collection of galaxies 450 million light-years away in cluster Abell S0740 near the constellation Centaurus.

The giant elliptical ESO 325-G004 looms large at the cluster's center. The galaxy, as massive as 100 billion of our suns, is home to thousands of globular clusters, small compact groups of hundreds of thousands of stars that are gravitationally bound systems. These clusters are dispersed spherically and uniformly in the outer halo of the elliptical and make their way around the center of the galaxy over the course of millions of years. Several foreground stars and background galaxies are also visible within the halo of this bright galaxy.

Other fuzzy elliptical galaxies dot the image. Some have evidence of a disk or ring structure that gives them a bow-tie shape. Several spiral galaxies are also present. The starlight in these galaxies is mainly contained in a disk and follows along spiral arms.

Recently, astronomers discovered that ESO325-004 is a "gravitational lens," caused when the focusing power of an enormous mass making up a galaxy causes the light from some background object, probably a distant "dwarf" galaxy, to be deflected and magnified. As a result, the more distant galaxy appears brighter and distorted into the shape of an arc, or ring. Gravitational lensing is a rare occurrence because it requires an almost perfect alignment of a distant galaxy with an intervening one that has enough mass to gravitationally focus the light.

This particular system is unique because it is closest known example of strong gravitational lensing and is close enough for the dynamics of its stars to be studied in detail using spectrographs on large ground-based telescopes, revealing how fast the stars in the galaxy are moving.

Dusty Stellar Nursery Revealed

How can something as big as a star go undetected? The answer is dust. Stellar nursery DR21 is shrouded in so much space dust that no visible light escapes it. By seeing in the infrared, NASA's Spitzer Space Telescope pulls this veil aside. The new observations reveal a firework-like display of massive stars surrounded by a stormy cloud of gas and dust. The biggest star is estimated to be 100,000 times as bright as our own sun.

Barsoom

"Yes, I have been to Barsoom again ..." begins John Carter in Edgar Rice Burroughs' 1913 science fiction classic The Gods of Mars. In Burroughs' novels of Carter's adventures, "Barsoom" is the local name for Mars. The red planet continues to capture the imagination of science fiction writers and scientists alike and serves as an impetus for exploration.

NASA's Exploration Rover Spirit wintered on a small hill known as "Low Ridge," producing this 360-degree view of the Martian surface. There, the rover's solar panels tilted toward the sun to maintain enough solar power for Spirit to keep making scientific observations throughout the winter on southern Mars. This view of the surroundings from Spirit's "Winter Haven" is presented in exaggerated color to enhance color differences among rocks, soils and sand.

Spirit completed its 1,000th sol of what was planned as a 90-sol mission. (A sol is a Martian day, which lasts 24 hours, 39 minutes, 35 seconds). The rover has lived through the most challenging part of its second Martian winter and its solar power levels are rising again. Spirit's panaromic camera began shooting component images of this panorama during sol 814 (April 18, 2006) and completed the part shown here on sol 932 (Aug. 17, 2006).

Spirit has stayed busy at Winter Haven during the six-month Martian winter even without driving, acquiring significant new assessments of the elemental chemistry and mineralogy of rocks and soil targets within reach of the rover's arm.

Saturn's Hyperion: A Moon With Odd Craters

What lies at the bottom of Hyperion's strange craters? Noone knows. To help find out, Cassini took this image, containing unprecedented detail, as the spacecraft swept past the sponge-textured moon in late 2005.

The image shows a remarkable world strewn with strange craters and odd surfaces. At the bottom of most craters lies some type of unknown dark material. Inspection of the image shows bright features indicating that the dark material might be only tens of meters thick in some places. Hyperion is about 250 kilometers across, rotates chaotically, and has a density so low that it might house a vast system of caverns inside

Big Spherules near Victoria

This frame from the microscopic imager on the Mars Exploration Rover Opportunity shows spherules up to about 5 millimeters (one-fifth of an inch) in diameter. The camera took this image during the 924th Martian day, or sol, of Opportunity's Mars-surface mission (Aug. 30, 2006), when the rover was about 200 meters (650 feet) north of Victoria Crater.

Opportunity discovered spherules like these, nicknamed "blueberries," at its landing site in "Eagle Crater," and investigations determined them to be iron-rich concretions that formed inside deposits soaked with groundwater. However, such concretions were much smaller or absent at the ground surface along much of the rover's trek of more than 5 kilometers (3 miles) southward to Victoria. The big ones showed up again when Opportunity got to the ring, or annulus, of material excavated and thrown outward by the impact that created Victoria Crater. Researchers hypothesize that some layer beneath the surface in Victoria's vicinity was once soaked with water long enough to form the concretions, that the crater-forming impact dispersed some material from that layer, and that Opportunity might encounter that layer in place if the rover drives down into the crater.

Echoes from the Edge

Variable star V838 Monocerotis lies near the edge of the Milky Way Galaxy, about 20,000 light-years from our sun. Still, ever since a sudden outburst was detected in January 2002, this enigmatic star has taken the center of an astronomical stage. As astronomers watch, light from the outburst echoes across pre-existing dust shells around V838 Mon, progressively illuminating ever more distant regions.

This stunning image of swirls of dust surrounding the star was recorded by the Hubble Space Telescope in September 2006. The picture spans about 14 light-years. Astronomers expect the expanding echoes to continue to light up the dusty environs of V838 Mon for at least the rest of the current decade. Researchers now have found that V838 Mon is likely a young binary star, but the cause of its extraordinary outburst remains a mystery.

Saturnian Psychedelia

This psychedelic view of Saturn and its rings is a composite made from images taken with the Cassini spacecraft wide-angle camera using spectral filters sensitive to wavelengths of infrared light. The image was acquired on Dec. 13, 2006 at a distance of approximately 822,000 kilometers (511,000 miles) from Saturn. Image scale is 46 kilometers (28 miles) per pixel.

Cat's Eye Nebula

Three thousand light-years away, the Cat's Eye Nebula, a dying star throws off shells of glowing gas. This image from the Hubble Space Telescope reveals the nebula to be one of the most complex planetary nebulae known. In fact, the features seen in the Cat's Eye are so complex that astronomers suspect the bright central object may actually be a binary star system. The term planetary nebula is misleading; although these objects may appear round and planet-like in small telescopes, high resolution images reveal them to be stars surrounded by cocoons of gas blown off in the late stages of stellar evolution.

NGC 602 and Beyond.

Near the outskirts of the Small Magellanic Cloud, a satellite galaxy some 200 thousand light-years distant, lies the young star cluster NGC 602. Surrounded by natal gas and dust, NGC 602 is featured in this Hubble image of the region. Fantastic ridges and undulating shapes strongly suggest that energetic radiation and shock waves from NGC 602's massive young stars have eroded the dusty material and triggered a progression of star formation moving away from the cluster's center. At the estimated distance of the Small Magellanic Cloud, the picture spans about 200 light-years, but a tantalizing assortment of background galaxies are also visible in the sharp Hubble view. The background galaxies are hundreds of millions of light-years or more beyond NGC 602.

Unfathomable

This scale comparison shows "the true place" of Earth and our Sun among the various giants of the universe. It is simultaneously sobering and mind-boggling experience.
First series of images starts with a Death Star, to further emphasize the futility of vain pride and ambition.

"We simply do not understand our place in the universe
and have not the courage to admit it"
-- Barry Lopez (American writer, b.1945)


"Really, the fundamental, ultimate mystery - the only thing you need to know to understand the deepest metaphysical secrets - is this: that for every outside there is an inside and for every inside there is an outside, and although they are different, they go together."
-- Alan Watts


"The universe is like a safe to which there is a combination.
But the combination is locked up in the safe."
-- Peter De Vries


"If the whole universe has no meaning, we should never have found out that it has no meaning: just as, if there were no light in the universe and therefore no creatures with eyes, we should never know it was dark. Dark would be without meaning."
-- C.S. Lewis


The Universe is a big place populated by stars and thoroughly confused humans.

Black Hole Grabs Starry Snack.

This artist's concept shows a supermassive black hole at the center of a remote galaxy digesting the remnants of a star. NASA's Galaxy Evolution Explorer had a "ringside" seat for this feeding frenzy, using its ultraviolet eyes to study the process from beginning to end.

The artist's concept chronicles the star being ripped apart and swallowed by the cosmic beast over time. First, the intact sun-like star (left) ventures too close to the black hole, and its own self-gravity is overwhelmed by the black hole's gravity. The star then stretches apart (middle yellow blob) and eventually breaks into stellar crumbs, some of which swirl into the black hole (cloudy ring at right). This doomed material heats up and radiates light, including ultraviolet light, before disappearing forever into the black hole. The Galaxy Evolution Explorer was able to watch this process unfold by observing changes in ultraviolet light.

The area around the black hole appears warped because the gravity of the black hole acts like a lens, twisting and distorting light.

Cosmic Epic Unfolds in Infrared

This majestic view, taken by NASA's Spitzer Space Telescope, tells an untold story of life and death in the Eagle Nebula, an industrious star-making factory located 7,000 light-years away in the Serpens Sonstellation. The image shows the region's entire network of turbulent clouds and newborn stars in infrared light.

The color green denotes cooler towers and fields of dust, including the three famous space pillars, dubbed the "Pillars of Creation," which were photographed by NASA's Hubble Space Telescope in 1995 (right of center; see http://www.nasa.gov/mission_pages/spitzer/multimedia/ssc2007-01b.html for exact location).

But it is the color red that speaks of the drama taking place in this region. Red represents hotter dust thought to have been warmed by the explosion of a massive star about 8,000 to 9,000 years ago. Since light from the Eagle Nebula takes 7,000 years to reach us, this supernova explosion would have appeared as an oddly bright star in our skies about 1,000 to 2,000 years ago.

According to astronomers' estimations, the explosion's blast wave would have spread outward and toppled the three pillars about 6,000 years ago (which means we wouldn't witness the destruction for another 1,000 years or so). The blast wave would have crumbled the mighty towers, exposing newborn stars that were buried inside, and triggering the birth of new ones.

STEREO's First View of the Sun.

Loops of highly charged particles burst from the sun's surface in this image, taken on Dec. 4, 2006. Among the first images taken by STEREO, the image shows the sun's roiling surface and atmosphere at temperatures around one million Kelvin (1.8 million degrees Fahrenheit).

The charged particles, mostly extremely hot protons and electrons, create a strong magnetic field that pulls the particles into the loops seen here. Over time, magnetic stress builds in the sun's atmosphere until the energy is released in a massive explosion. The explosion sends a giant cloud of charged particles (a coronal mass ejection) and x-ray solar flares hurtling into space with a force comparable to a billion megaton nuclear bombs. When the charged particles and x-rays bombard the Earth, they can disrupt communications and power systems and are a threat to satellites and astronauts in space.

Understanding the difference between harmful and harmless coronal mass ejections is one of the biggest questions that scientists studying the face of the sun. Currently, scientists only see ejections in one dimension. To understand how solar storms travel through the solar systems, scientists need a three-dimensional view of the storms.

STEREO, launched on Oct. 25, 2006, consists of observation systems orbiting the sun in front of and behind the Earth. Just as our two eyes give us a three-dimensional view of the world, the views provided by each STEREO system can be combined to provide a three-dimensional view of the sun. Though the first STEREO images were taken in early December, the two systems won't be in position to give three dimensional images until April 2007.

Cyclones in Tandem

A cyclone is a low-pressure area of winds that spiral inwards. Although tropical storms most often come to mind, these spiraling storms can also form at mid- and high latitudes. Two such cyclones formed in tandem in November 2006. MODIS, flying onboard NASA's Terra satellite, took this picture on Nov. 20. This image shows the cyclones south of Iceland. Scotland appears in the lower right. The larger and perhaps stronger cyclone appears in the east, close to Scotland.

Cyclones at high and mid-latitudes are actually fairly common, and they drive much of the Earth's weather. In the Northern Hemisphere, cyclones move in a counter-clockwise direction, and both of the spiraling storms in this image curl upwards toward the northeast then the west. The eastern storm is fed by thick clouds from the north that swoop down toward the storm in a giant "V" shape on either side of Iceland. Skies over Iceland are relatively clear, allowing some of the island to show through. South of the storms, more diffuse cloud cover swirls toward the southeast.

White Dwarf Stars

Pushing the limits of its powerful vision, NASA's Hubble Space Telescope uncovered the oldest burned-out stars in our Milky Way Galaxy. These extremely old, dim "clockwork stars" provide a completely independent reading on the age of the universe.

The ancient white dwarf stars, as seen by Hubble, are 12-13 billion years old. Because earlier Hubble observations show that the first stars formed less than 1 billion years after the universe's birth in the big bang, finding the oldest stars puts astronomers well within arm's reach of calculating the absolute age of the universe.

Though previous Hubble research sets the age of the universe at 13-14 billion years based on the rate of expansion of space, the universe's birthday is such a fundamental and profound value that astronomers have long sought other age-dating techniques to cross-check their conclusions.

Globular clusters are the first pioneer settlers of the Milky Way. Many coalesced to build the hub of our galaxy and formed billions of years before the appearance of the Milky Way's magnificent pinwheel disk. Today 150 globular clusters survive in the galactic halo. The globular cluster M4 was selected because it is the nearest to Earth, so the intrinsically feeblest white dwarfs are still apparently bright enough to be picked out by Hubble.

Dazzling Dunes.

As NASA's Mars Exploration Rover Opportunity creeps farther into "Endurance Crater," the dune field on the crater floor appears even more dramatic. This false-color image taken by the rover's panoramic camera shows that the dune crests have accumulated more dust than the flanks of the dunes and the flat surfaces between them. Also evident is a "blue" tint on the flat surfaces as compared to the dune flanks. This results from the presence of the hematite-containing spherules, or "blueberries", that accumulate on the flat surfaces.

Sinuous tendrils of sand less than 1 meter (3.3 feet) high extend from the main dune field toward the rover. Scientists hope to send the rover down to one of these tendrils in an effort to learn more about the characteristics of the dunes. Dunes are a common feature across the surface of Mars, and knowledge gleaned from investigating the Endurance dunes may apply to similar dunes elsewhere.

Before the rover heads down to the dunes, rover drivers must first establish whether the slippery slope that leads to them is firm enough to ensure a successful drive back out of the crater. Otherwise, such hazards might make the dune field a true sand trap.