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.