This Hubble telescope photo mosaic shows a field of distant galaxies.
The brightest object in this picture is NGC 4881 [just above center], an elliptical galaxy in the outskirts of the Coma Cluster, a great cluster of galaxies more than five times farther away than the Virgo Cluster. The distance to the Coma Cluster is an important cosmic yardstick for scaling the overall size of the universe.
Two groups have recently used the Hubble telescope to acquire high-resolution images of the planet Neptune. These images represent the clearest views of Neptune since the Voyager 2 flyby in August 1989. The observations are providing a wealth of new information about the structure, composition, and meteorology of this distant planet's atmosphere.
The pictures show several bright clouds, which are thought to be high above the main cloud deck and above much of the absorbing methane gas. The edge of the planet's disk also appears somewhat bright, indicating the presence of a ubiquitous high-altitude haze layer.
Hubble Identifies a Long-Sought Population of Comets Beyond Neptune
The Hubble telescope has detected a long-sought population of comets dwelling at the icy fringe of the solar system. The observation, which is the astronomical equivalent to finding the proverbial needle-in-a-haystack, bolsters proof for a primordial comet reservoir just beyond Neptune. The circles pinpoint one of the candidate Kuiper belt objects. The dotted lines represent a possible orbit that this Kuiper belt comet is following.
Based on the Hubble observations, a team of astronomers estimate that the belt contains at least 200 million comets, which have remained essentially unchanged since the birth of the solar system 4.5 billion years ago.
Hubble Sheds Light on the "Faint Blue Galaxy" Mystery
Astronomers using the Hubble telescope have solved a 20-year-old mystery by showing that a class of galaxies once thought to be rare is actually the most common type of galaxy in the universe.
Analyzing some of the deepest images ever taken of the heavens, the astronomers conclude that small irregular objects called "blue dwarfs" were more numerous several billion years ago, outnumbering giant elliptical galaxies and spiral galaxies like our Milky Way. This means that blue dwarfs are a more important constituent of the universe and figure more prominently in the evolution of galaxies than previously thought.
Astronomers have announced the discovery of at least two, and possibly as many as four, new moons orbiting the giant planet Saturn. This discovery was based upon Hubble telescope images that were taken when Saturn's rings were tilted edge-on to Earth.
Two of the satellites seen by Hubble are in orbits similar to those of Atlas and Prometheus, a pair of moons discovered in 1980 by the Voyager 1 spacecraft. Additional Hubble observations of Saturn will provide more images that can be used to determine whether two of the four satellites detected by Hubble are truly new or not. This four-picture sequence shows one of the new moons discovered by Hubble. Saturn appears as a bright white disk at far right, and the edge-on rings extend diagonally to the upper left.
Hubble Uncovers Surprisingly Complex Structures in Radio Galaxies
Probing some of the most distant and energetic galaxies in the universe, the Hubble telescope has uncovered surprisingly varied and intricate structures of stars and gas, suggesting that the processes powering these so-called radio galaxies are more complex than previously thought.
The radio galaxies observed are far across the cosmos, existing when the universe was half its present age. Light from these galaxies is just now reaching Earth. The Hubble observations should shed light on galaxy evolution and on the nature of active galaxies, which may be powered by immense black holes at their cores. These Hubble images, combined with radio maps produced by the Very Large Array Radio Interferometer [blue contour lines], show surprisingly varied and intricate structures of gas and stars.
Saturn's magnificent ring system is seen tilted edge-on - for the second time in 1995 - in this Hubble telescope picture taken Aug. 10, when the planet was 895 million miles (1,440 million kilometers) away from Earth. Hubble snapped the image as Earth sped back across Saturn's ring plane to the sunlit side of the rings.
Several of Saturn's icy moons are visible as tiny star-like objects in or near the ring plane. On May 22, 1995 Earth dipped below the ring plane, giving observers a brief look at the backlit side of the rings. Ring-plane crossing events occur approximately every 15 years. Earthbound observers won't have as good a view until the year 2038.
Peering deep into the globular star cluster M4 with the Hubble telescope, Canadian and American astronomers have discovered a large number of "stellar corpses," called white dwarf stars, which may be used eventually to refine age estimates of the universe.
The observation was so sensitive that even the brightest of the detected white dwarfs was no more luminous than a 100-watt light bulb seen at the moon's distance (239,000 miles). A Hubble color image of a small portion of the cluster reveals eight white dwarf stars [inside the white circles] among the cluster's much brighter population of yellow, Sun-like stars and cooler red dwarf stars. Hubble reveals a total of 75 white dwarfs in one small area within M4 out of a total of about 40,000 white dwarfs that the cluster is predicted to contain. The picture on the left is a view of the cluster taken by a ground-based telescope.
This Hubble telescope picture reveals one of the least massive and coolest stars ever seen [upper right]. This star is a diminutive companion to the K dwarf star called GL 105A (also known as HD 16160), seen at lower left. The pair is located 27 light-years from Earth in the constellation Cetus.
Based on the Hubble observation, astronomers calculate that the cool, lightweight star, called GL 105C, is 25,000 times fainter than GL 105A in visible light. If the dim companion were at the distance of our Sun, it would be only four times brighter than the full moon.
Hubble Photo Gallery of Jupiter's Galilean Satellites
This is a Hubble telescope "family portrait" of Jupiter's four largest moons.
Located approximately a half billion miles away, the moons are so small that, in visible light, they appear as fuzzy disks in the largest ground-based telescopes. Hubble can resolve surface details seen previously only by the Voyager space probes in the early 1980s. While the Voyager probes provided close-up snapshots of the satellites, Hubble can now follow changes on the moons and reveal other characteristics at ultraviolet and near-infrared wavelengths.
Though ozone may be diminishing on Earth, it is being manufactured one-half billion miles away, on Jupiter's largest satellite, Ganymede.
NASA's Hubble Space Telescope found ozone's spectral "fingerprint" during observations of Ganymede made by Keith Noll and colleagues at the Space Telescope Science Institute in Baltimore, Maryland. These Hubble Faint Object Spectrograph results were presented at the American Astronomical Society's 27th Annual Meeting of the Division of Planetary Sciences in Kona, Hawaii.
This pair of images of Jupiter's volcanic moon Io, taken with the Hubble telescope, shows the surprising emergence of a 200-mile-wide, yellowish-white feature near the center of the moon's disk [photo on the right]. This represents a more dramatic change in 16 months than any seen over the previous 15 years, say researchers. They suggest the spot may be a new class of transient feature on the moon. For comparison the photo on the left was taken in March 1994, before the spot emerged. The photo indicates that Io's surface had undergone only subtle changes since it was last seen close-up by the Voyager 2 probe in 1979.
Hubble Sees Thin Disk Around the Star Beta Pictoris
This Hubble telescope image of a portion of a vast dust disk around the star Beta Pictoris [top picture] shows that the disk is thinner than previously thought. Estimates based on the Hubble snapshot place the disk's thickness as no more than one billion miles (600 million kilometers). For comparison the disk appears four times thicker in a ground-based image.
The disk is tilted nearly edge-on to Earth and may be older than some previous estimates because its dust has had enough time to settle into a flat plane. A thin disk also increases the probability that comet-sized or larger bodies have formed through accretion in the disk. Both conditions are believed to be characteristic of a hypothesized circumstellar disk around our own Sun, which was a necessary precursor to the planet-building phase of our solar system, according to current theory.
Hubble Provides the First Images of Saturn's Aurorae
The Hubble telescope has taken the first picture of bright aurorae at Saturn's northern and southern poles [top picture]. The picture at the bottom was taken in visible light.
Hubble's far-ultraviolet-light image resolves a luminous, circular band centered on the north pole, where an enormous curtain of light rises as far as 1,200 miles (2,000 kilometers) above the cloud tops. This curtain changed rapidly in brightness and extent over the two-hour period of observations.
These two surface maps of the asteroid Vesta are derived from Hubble telescope images taken between November 28 and December 1, 1994. The pictures show surface details as small as 35 miles across. Vesta is 320 miles in diameter, and the map covers the asteroid's entire surface area, about 200,000 miles.
The top panel indicates sharp contrasts in Vesta's surface color. The surface markings may represent ancient volcanic activity such as lava flows and, in addition, regions where major collisions have stripped away the surface. The bottom panel reveals that Vesta's surface is made up of igneous rock, indicating that either the entire surface was once melted or lava flowing from its interior once completely covered its surface.
These Hubble telescope pictures of comet Hale-Bopp show a remarkable "pinwheel" pattern and a blob of free-flying debris near its center. The image at left shows the entire comet; the picture at right is a close-up of the nucleus.
The bright clump of light along the spiral [just above the center of the picture] may be a piece of the comet's icy crust. Although the "blob" is about 3.5 times fainter than the brightest portion at the comet's center, the lump appears brighter because it covers a larger area. The debris follows a spiral pattern outward because the solid center is rotating like a lawn sprinkler, completing a single rotation about once per week.
Hubble Discovers New Class of Gravitational Lens for Probing the Structure of the Cosmos
The Hubble telescope has discovered a new, distant class of quadruple or cross-shaped gravitational lenses. The new class of objects might eventually provide astronomers with a powerful "magnifying glass" for probing a variety of characteristics of the universe: the distribution of dark matter, the abundance of super-massive black holes, and the eventual fate of the universe.
In Hubble pictures of two such objects, astronomers have found four images of a faraway galaxy [the blue blobs] gathered around a red elliptical galaxy. A gravitational lens is produced by a massive object's enormous gravitational field, which bends light to magnify, brighten, and distort the image of a more distant object.
Eerie, dramatic pictures from the Hubble telescope show newborn stars emerging from "eggs" – not the barnyard variety – but rather, dense, compact pockets of interstellar gas called evaporating gaseous globules (EGGs). Hubble found the "EGGs," appropriately enough, in the Eagle nebula, a nearby star-forming region 7,000 light-years from Earth in the constellation Serpens.
These striking pictures resolve the EGGs at the tip of finger-like features protruding from monstrous columns of cold gas and dust in the Eagle Nebula (also called M16). The columns – dubbed "elephant trunks" – protrude from the wall of a vast cloud of molecular hydrogen, like stalagmites rising above the floor of a cavern. Inside the gaseous towers, which are light-years long, the interstellar gas is dense enough to collapse under its own weight, forming young stars that continue to grow as they accumulate more and more mass from their surroundings.
Hubble Peers Deep into the Crowded Heart of the Densest Known Star Cluster
By pinpointing individual suns in the glare of the most tightly packed cluster of stars in our galaxy, the Hubble telescope has unveiled hints of either a massive black hole or another remarkable phenomenon: a "core collapse" driven by the intense gravitational pull of so many stars in such a small volume of space.
Astronomers used the telescope's sharp images to count an extraordinary number of stars in the ancient globular cluster M15, about 37,000 light-years from Earth. Hubble spied hundreds of stars in a tiny area at the center of this cluster. Careful analysis of the distribution of these and thousands of neighboring stars suggest that at some point in the distant past, the stars converged on M15's core, like bees swarming to their hive. An alternate scenario also could explain the pileup of stars at M15's core: a black hole that may have formed early in the cluster's history. The black hole would have gradually gained mass as more stars spiraled inward. The black-and-white picture shows the cluster's central region; the color image is a close-up of the core.
Hubble Views the Galileo Probe Entry Site on Jupiter
This Hubble telescope image of Jupiter
was taken when the giant planet was 534 million miles (854 million kilometers) from Earth. The arrow points to the predicted site at which the Galileo probe will enter Jupiter's atmosphere on December 7, 1995. At this latitude, the eastward winds have speeds of about 250 mph (110 meters per second). The white oval to the north of the probe site drifts westward at 13 mph (6 meters per second), rolling in the winds, which increase sharply toward the equator.
The four enlarged Hubble images of Jupiter's equatorial region
show clouds sweeping across the predicted Galileo probe entry site, which is at the exact center of each frame. A tiny white dot marks the predicted entry site.
