Wonderful long exposure photographs taken by astronaut Don Pettit. While there are many photos like these taken from the perspective of the Earth’s surface, Pettit’s images are unique in that they incorporate the passing blur of entire illuminated cities, aurora, and the sporadic flashes of lightening from thunderstorms. Check out many more photos from the series here.
We value gold for many reasons: its beauty, its usefulness as jewelry, and its rarity. Gold is rare on Earth in part because it’s also rare in the universe. Unlike elements like carbon or iron, it cannot be created within a star. Instead, it must be born in a more cataclysmic event - like one that occurred last month known as a short gamma-ray burst (GRB). Observations of this GRB provide evidence that it resulted from the collision of two neutron stars - the dead cores of stars that previously exploded as supernovae. Moreover, a unique glow that persisted for days at the GRB location potentially signifies the creation of substantial amounts of heavy elements - including gold.
A gamma-ray burst is a flash of high-energy light (gamma rays) from an extremely energetic explosion. Most are found in the distant universe. Berger and his colleagues studied GRB 130603B which, at a distance of 3.9 billion light-years from Earth, is one of the nearest bursts seen to date.
Gamma-ray bursts come in two varieties - long and short - depending on how long the flash of gamma rays lasts. GRB 130603B, detected by NASA’s Swift satellite on June 3rd, lasted for less than two-tenths of a second.
Although the gamma rays disappeared quickly, GRB 130603B also displayed a slowly fading glow dominated by infrared light. Its brightness and behavior didn’t match a typical “afterglow,” which is created when a high-speed jet of particles slams into the surrounding environment.
Instead, the glow behaved like it came from exotic radioactive elements. The neutron-rich material ejected by colliding neutron stars can generate such elements, which then undergo radioactive decay, emitting a glow that’s dominated by infrared light - exactly what the team observed.
The team calculates that about one-hundredth of a solar mass of material was ejected by the gamma-ray burst, some of which was gold. By combining the estimated gold produced by a single short GRB with the number of such explosions that have occurred over the age of the universe, all the gold in the cosmos might have come from gamma-ray bursts.
GRAVITATIONAL WAVES — PATTERNS IN SPACE-TIME A popular (and creative) form of scientific illustration [Creative, because gravity waves may not actually exist — although the smart money (NSF) is betting that they do.]
Telescopes have been observing waves for a long time. The ones used by past astronomers were designed to make visible light waves more visible. Over time, people came to understand that there was more to the universe than what humans can register with their eyes, and started measuring radio, ultraviolet, and x-ray waves.
Most recently, scientists have turned their attention to measuring gravitational waves."Gravitational telescopes" let scientists observe fluctuations in spacetime itself.
One way of picturing gravitational waves is to imagine the universe as a stretched-out piece of fabric. Planets and stars sitting on the fabric pull it out of shape, and anything placed close to them will fall towards them.
If heavier objects, like stars and black holes, remain still, then the fabric is still as well. On the other hand, if things like neutron stars or black holes are romping around like happy, infinitely-massive puppies, the fabric will dip and ripple around them.
Those ripples in the universe are what scientists call gravitational waves. __________________________________
NASA’s SOFIATelescope Images Ring Of Dust Surrounding Black Hole
Astronomers using a telescope attached to a modified Boeing 747SP aircraft have captured new images of a ring of gas and dust seven light-years in diameter surrounding the super-massive black hole at the center of the Milky Way.
The team used NASA’s Stratospheric Observatory for Infrared Astronomy (SOFIA) to capture images of our galaxy’s circumnuclear ring (CNR), as well as a neighboring cluster of extremely luminous young stars known as the quintuplet cluster (QC).
The mid-infrared image of the CNR shows off bright Y-shaped features believed to be material falling from the ring toward the black hole that is located where the arms of the “Y” intersect. The neighboring cluster is located about 100 light years away from the galaxy’s nucleus.
In this rare image taken on July 19, 2013, the wide-angle camera on NASA’s Cassini spacecraft has captured Saturn’s rings and our planet Earth and its moon in the same frame. It is only one footprint in a mosaic of 33 footprints covering the entire Saturn ring system (including Saturn itself). At each footprint, images were taken in different spectral filters for a total of 323 images: some were taken for scientific purposes and some to produce a natural color mosaic. This is the only wide-angle footprint that has the Earth-moon system in it.
The dark side of Saturn, its bright limb, the main rings, the F ring, and the G and E rings are clearly seen; the limb of Saturn and the F ring are overexposed. The “breaks” in the brightness of Saturn’s limb are due to the shadows of the rings on the globe of Saturn, preventing sunlight from shining through the atmosphere in those regions. The E and G rings have been brightened for better visibility.
Earth, which is 898 million miles (1.44 billion kilometers) away in this image, appears as a blue dot at center right; the moon can be seen as a fainter protrusion off its right side. An arrow indicates their location in the annotated version. (The two are clearly seen as separate objects in the accompanying narrow angle frame: PIA14949.) The other bright dots nearby are stars.
This is only the third time ever that Earth has been imaged from the outer solar system. The acquisition of this image, along with the accompanying composite narrow- and wide-angle image of Earth and the moon and the full mosaic from which both are taken, marked the first time that inhabitants of Earth knew in advance that their planet was being imaged. That opportunity allowed people around the world to join together in social events to celebrate the occasion.
This artist’s concept shows a possible model of Titan’s internal structure that incorporates data from NASA’s Cassini spacecraft. In this model, Titan is fully differentiated, which means the denser core of the moon has separated from its outer parts. This model proposes a core consisting entirely of water-bearing rocks and a subsurface ocean of liquid water. The mantle, in this image, is made of icy layers, one that is a layer of high-pressure ice closer to the core and an outer ice shell on top of the sub-surface ocean.
A model of Cassini is shown making a targeted flyby over Titan’s cloudtops, with Saturn and Enceladus appearing at upper right.
The model, developed by Dominic Fortes of University College London, England, incorporates data from Cassini’s radio science experiment.
The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA’s Science Mission Directorate, Washington, D.C. The Cassini orbiter was designed, developed and assembled at JPL. The radio science team is based at Wellesley College, Wellesley, Mass.
The close proximity of COROT-7b to its star (just 1.6 million miles) keeps it gravitationally locked in place just as the moon is to the Earth, meaning the same side of always faces the star. As such, it stays very, very hot there (about 4,220 degrees Fahrenheit). That kind of heat vaporizes rocks, and that’s exactly what happens on COROT-7b. Using computer modeling, the team at Washington ran through four different scenarios with four different starting compositions (since the exact makeup of the planet is unknown) with the same result each time.
Just as water vaporizes in our atmosphere only to condense at higher, cooler altitudes and fall back to the Earth as rain, so do the sodium, potassium, silicon monoxide, magnesium, aluminum, calcium and iron of COROT-7b. When they condense, however, they condense into rock clouds that rain little pebbles of different types of rocks. What’s more, the type of rock is dependent on altitude. The atmosphere gets colder the higher up the rock vapor goes. Since each rock or mineral has a different boiling point, the materials with the highest boiling points will condense out at lower altitudes, while the ones with lower boiling points can rise higher as vapor before condensing back into rocks.
Uranus, photographed by the Hubble Space Telescope through various filters. Of note is what appears to be a cloud centre-right; Uranus looked almost completely featureless in Voyager’s pictures, but at least at some wavelengths, there is something going on in the atmosphere. The rings are also clearly visible in the last few frames (892nm methane filter). Assuming I made no interpretational blunders with HORIZONS data, Miranda is the small moon at the bottom of the frame, and Ariel is near the top.