We seem to be inside a "local bubble" in a network of cavities in the interstellar medium, probably carved by massive star explosions millions of years ago. The interstellar medium (or ISM) is the matter that exists in the space between the star systems in a galaxy. This matter includes gas in ionic, atomic, and molecular form, dust, and cosmic rays. It fills interstellar space and blends smoothly into the surrounding intergalactic space.
Continue reading ""We Exist Inside a Bubble in the Interstellar Medium" -- NASA Astronomers (Weekend Feature)" »
Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile discovered that planets orbiting the star Fomalhaut must be much smaller than originally thought. The discovery was made possible by exceptionally sharp ALMA images of a disc, or ring, of dust orbiting Fomalhaut, which lies about 25 light-years from Earth. It helps resolve a controversy among earlier observers of the system.
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Astronomers using the NASA/ESA Hubble Space Telescope have obtained a remarkable new view of a whopper of an elliptical galaxy, with a core bigger than any seen before. There are two intriguing explanations for the puffed up core, both related to the action of one or more black holes, and the researchers have not yet been able to determine which is correct. Spanning a little over one million light-years, the galaxy is about ten times the diameter of the Milky Way galaxy. The bloated galaxy is a member of an unusual class of galaxies with an unusually diffuse core filled without any a concentrated peak of light around a central black hole.
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This bubble-like emission nebula, known as Thor's Helmet, is approximately 30 light-years across and located in the Constellation Canis Major at a distance of about 15,000 light-years. We don't know what caused the bubbles and arcs in NGC 2359, but the main culprit is the massive Wolf-Rayet star located slightly left from the image center.
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A new study using data from NASA's Spitzer Space Telescope suggests a cause for the mysterious glow of infrared light seen across the entire sky. It comes from isolated stars beyond the edges of galaxies. These stars are thought to have once belonged to the galaxies before violent galaxy mergers stripped them away into the relatively empty space outside of their former homes.
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Astronomers using NASAs Spitzer Space Telescope have greatly improved the cosmic distance ladder used to measure the expansion rate of the universe, as well as its size and age. The cosmic distance ladder, symbolically shown here in this artist's concept, is a series of stars and other objects within galaxies that have known distances. By combining these distance measurements with the speeds at which objects are moving away from us, scientists can calculate the expansion rate of the universe, also known as Hubble's Constant.
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The heat-seeking capabilities of the international Cassini spacecraft and two ground-based telescopes have provided the first look at the aftermath of Saturn’s ‘Great Springtime Storm’. Concealed from the naked eye, a giant oval vortex is persisting long after the visible effects of the storm subsided. As the visible storm erupted in the roiling cloud deck of Saturn’s troposphere, waves of energy rippled hundreds of kilometres upwards, depositing their energy as two vast ‘beacons’ of hot air in the stratosphere. The beacons were expected to cool down and dissipate, but by late April 2011 – by which time bright cloud material had encircled the entire planet – the hot spots had merged to create an enormous vortex that for a brief period exceeded even the size of Jupiter’s famous Great Red Spot.
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The deepest ocean on Earth is the Pacific Ocean's Marianas Trench, which reaches a depth of 6.8 miles awesomely trumped by the depth of the ocean on the Jupiter's moon, Europa, which some measurements put at 62 miles. Although Europa is covered in a thick crust of scarred and cross-hatched ice, measurements made by NASA's Galileo spacecraft and other probes strongly suggest that a liquid ocean lies beneath that surface. The interior is warmed, researchers believe, by the tidal stresses exerted on Europa by Jupiter and several other large moons, as well as by radioactivity.
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A team led by geochemists at the University of California, Riverside challenges the so-called Great Oxidation Event 2.4 billion years ago, and the simple notion of an up-only trend for early oxygen and provides the first compelling direct evidence for a major drop in oxygen after the first rise. The Great Oxidation was critical for the origin and evolution of the first forms of eukaryotic life. The second big step in the up-only hypothesis occurred almost two billion years later, coinciding with the first appearances and earliest diversification of animals.
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