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Cosmology Astrophysics Astronomy
Latest Activity: 3 hours ago
Cosmology - Astrophysics - Astronomy
Hubble Wallpaper - Awesome Hubble Images
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The Last Goodbye
Ask Ethan: Why Did Light Arrive 1.7 Seconds After Gravitational Waves In The Neutron Star Merger? (Synopsis)
Five Discoveries In Fundamental Physics That Came As Total Surprises
Even while the world suffers, investing in science is non-negotiable (Synopsis)
Merging Neutron Stars Deliver Deathblow To Dark Matter And Dark Energy Alternatives (Synopsis)
Explanation: Close to the Great Bear (Ursa Major) and surrounded by the stars of the Hunting Dogs (Canes Venatici), this celestial wonder was discovered in 1781 by the metric French astronomer Pierre Mechain. Later, it was added to the catalog of his friend and colleague Charles Messier as M106. Modern deep telescopic views reveal it to be an island universe -- a spiral galaxy around 30 thousand light-years across located only about 21 million light-years beyond the stars of the Milky Way. Along with a bright central core, this colorful composite image highlights youthful blue star clusters and reddish stellar nurseries tracing the galaxy's spiral arms. It also shows off remarkable reddish jets of glowing hydrogen gas. In addition to small companion galaxy NGC 4248 (bottom right) background galaxies can be found scattered throughout the frame. M106 (aka NGC 4258) is a nearby example of the Seyfert classof active galaxies, seen across the spectrum from radio to x-rays. Active galaxies are believed to be powered by matter falling into a massive central black hole.
STARS plunging into the giant black hole at the centre of our galaxy can explain two huge bubbles of gamma rays that NASA's Fermi space telescope discovered last year. The bubbles tower 25,000 light years above and below the Milky Way's disc of stars.
Read more in the discussion above.
5.6k Saturn Cassini Photographic Animation from stephen v2 on Vimeo.
How the Japan quake moved the Earth on it's axis.
Experts have said the force of the earthquake in Japan shifted the earth's axis by 25 centimetres and shortened the day by 1.8 microseconds - but what does this mean?Italy's National Institute of Geophysics and Volcanology has calculated that the earth's axis moved by a quarter of a metre as a result of the devastating 8.9 magnitude earthquake in Japan, the largest ever recorded in the country.The US Geological Survey said the main island of Japan had moved 2.4 metres as a result of the quake. It also said hundreds of aftershocks have hit Japan since the main quake, at least two dozen of which have topped magnitude 6, the size of the Christchurch earthquake.More on the science of the quake from Channel 4 NewsJapan earthquake: planning for disasterTsunami science: a wall of waterJapan: how dangerous are nuclear blasts? The earthquake, which has had an appalling impact in Japan after causing a huge tsunami, is the fifth most powerful to hit the world in the past century.It surpassed Japan's biggest previous tremor, the Great Kanto Quake of 1923, which had a magnitude of 7.9 and killed more than 140,000 people in the Tokyo area.Channel 4 News special report - Japan: tsunami to nuclear crisisIt has also shortened the length of a day on earth by around 1.8 microseconds. To put that into context, one earth day is 24 hours, or 86,400 seconds long.The length of days varies by around 1 millisecond a year naturally - 1,000 microseconds - and this isn't the first time an earthquake has had an impact on time in this way. Last year's earthquake in Chile, which had an 8.8 magnitude, also sped up the earth's rotation and shaved 1.26 microseconds off the day.
Jupiter dominates the other planets in our solar system. Like all planets above a certain size, it is a gas giant made mainly of hydrogen and helium. The gassiest of all known gas giants, the unromantically named TrES-4, was discovered in 2006 orbiting a brightish star 1500 light years from Earth. Its diameter of about 1.8 times Jupiter's makes it the largest accurately measured planet. Strangely, though, TrES-4 is very light for its size. It has only 88 per cent of Jupiter's mass, giving it a density of roughly 0.2 grams per cubic centimetre, less than that of cork. Just how a planet can be as fluffy as TrES-4 remains a mystery.
Update: Science is never still in its pursuit of cosmic extremes: since this story was filed, new observations of the exoplanet WASP-17b suggest that it is even bigger than TrES-4b, with a radius almost twice Jupiter's. The exoplanet is some 1000 light years from Earth and has a mass of just half Jupiter's, making it an even fluffier mystery than TrES-4b.
Unless a giant alien monolith has appeared while this article was in press, the biggest known artificial structure in space is the International Space Station, 109 metres across and weighing 370 tonnes.
According to the standard model of galaxy formation, the biggest galaxies are elliptical monsters formed from the collision of many smaller galaxies. The largest known example is the lens-shaped IC 1101, a billion light years away in the centre of the Abell 2029 galaxy cluster. IC 1101 is close to 6 million light years across, making it thousands of times the volume of the Milky Way.
Not a black hole, for a change, but a vaster expanse of darkness. On the largest scales explored, galaxies are arranged into great walls and knots as much as a few hundred million light years across, with voids in between. The biggest known void - freakishly large at around a billion light years - was found in 2007. One outlandish suggestion is that it is a blemish left by an ancient close encounter with another universe.
A star called VY Canis Majoris, 5000 light years from Earth could swallow our sun 8 billion times over. Probably. Its estimated diameter of nearly 3 billion kilometres puts VY Canis Majoris in with a handful of stars that have earned the title red hypergiant. This estimate is contested, however, and some say the star is a mere red supergiant only 1 billion kilometres across.
New Scientist 12 March 2011
WE THINK of stars, even the failed ones called brown dwarfs, as being lethally hot. That picture has been confounded by a newly discovered brown dwarf - at room temperature.
Like fully fledged stars, brown dwarfs form from collapsing gas clouds, but they are not massive enough to sustain nuclear reactions. Instead, they briefly shine red from the heat of formation, then fade. Still, the coolest known brown dwarfs are all hot enough to roast any spacefarers who venture too close.
Now Kevin Luhman of Pennsylvania State University in University Park and colleagues have used NASA's infrared Spitzer Space Telescope to detect the glow of what appears to be a brown dwarf at just 30 °C (Astrophysical Journal Letters, DOI: 10.1088/2041-8205/730/1/L9).
The object, which orbits a white dwarf star 63 light years from Earth, weighs seven times as much as Jupiter. At that mass, it would normally be considered a planet. But planets form from discs of gas and dust around stars, and the researchers say that the object, known as WD 0806-661 B, lies too far from its star - at 2500 times the Earth's distance from the sun - to be deemed a planet if it formed where it is.
The object is a lot hotter than Jupiter, which is at a frigid -149 °C, and much cooler than the next coolest brown dwarf, at 100 °C. This means that WD 0806-661 B will act as a "missing link" to reveal how temperature affects the atmosphere and spectral features of objects that are roughly the size of Jupiter.
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