NASA dicit:
New NASA and Durham University simulations put forth a theory of the origin of Saturn’s rings and icy moons – they may have formed following a massive collision between two moons orbiting the gas giant. The simulations used in this research are some of the most detailed of their kind to study the formation of Saturn’s rings and potentially habitable icy moons.
Video credit: NASA/Jacob Kegerreis/LuÃs Teodoro
NASA dicit:
The animation highlights the “super†in supermassive black holes. These monsters lurk in the centers of most big galaxies, including our own Milky Way, and contain between 100,000 and tens of billions of times more mass than our Sun.
Any light crossing the event horizon – the black hole’s point of no return – becomes trapped forever, and any light passing close to it is redirected by the black hole’s intense gravity. Together, these effects produce a “shadow†about twice the size of the black hole’s actual event horizon.
The animation shows 10 supersized black holes that occupy center stage in their host galaxies, including the Milky Way and M87, scaled by the sizes of their shadows. Starting near the Sun, the camera steadily pulls back to compare ever-larger black holes to different structures in our solar system.
First up is 1601+3113, a dwarf galaxy hosting a black hole packed with the mass of 100,000 Suns. The matter is so compressed that even the black hole’s shadow is smaller than our Sun.
The black hole at the heart of our own galaxy, called Sagittarius A* (pronounced ay-star), boasts the weight of 4.3 million Suns based on long-term tracking of stars in orbit around it. It’s shadow diameter spans about half that of Mercury’s orbit in our solar system.
The animation shows two monster black holes in the galaxy known as NGC 7727. Located about 1,600 light-years apart, one weighs 6 million solar masses and the other more than 150 million Suns. Astronomers say the pair will merge within the next 250 million years.
At the animation’s larger scale lies M87’s black hole, now with a updated mass of 5.4 billion Suns. Its shadow is so big that even a beam of light – traveling at 670 million mph (1 billion kph) – would take about two and a half days to cross it.
The movie ends with TON 618, one of a handful of extremely distant and massive black holes for which astronomers have direct measurements. This behemoth contains more than 60 billion solar masses, and it boasts a shadow so large that a beam of light would take weeks to traverse it.
Video credit: NASA Goddard
NASA dicit:
A new study using the now-retired Stratospheric Observatory for Infrared Astronomy (SOFIA) has pieced together the first detailed, wide-area map of water distribution on the Moon. The new map covers about one-quarter of the Earth-facing side of the lunar surface below 60 degrees latitude and extends to the Moon’s South Pole. In this data visualization, SOFIA’s lunar water observations are indicated using color, with blue representing areas of higher water signal, and brown lower.
Video credit: NASA’s Goddard Space Flight Center Scientific Visualization Studio/Ernie Wright
Wikipedia dicit:
Plasma (from Ancient Greek πλάσμα (plásma) ‘moldable substance’) is one of four fundamental states of matter, characterized by the presence of a significant portion of charged particles in any combination of ions or electrons. It is the most abundant form of ordinary matter in the universe, being mostly associated with stars, including the Sun. Extending to the rarefied intracluster medium and possibly to intergalactic regions, plasma can be artificially generated by heating a neutral gas or subjecting it to a strong electromagnetic field.
The presence of charged particles makes plasma electrically conductive, with the dynamics of individual particles and macroscopic plasma motion governed by collective electromagnetic fields and very sensitive to externally applied fields. The response of plasma to electromagnetic fields is used in many modern devices and technologies, such as plasma televisions or plasma etching.
Depending on temperature and density, a certain number of neutral particles may also be present, in which case plasma is called partially ionized. Neon signs and lightning are examples of partially ionized plasmas. Unlike the phase transitions between the other three states of matter, the transition to plasma is relatively not well defined and is a matter of interpretation and context. Whether a given degree of ionization suffices to call a substance ‘plasma’ depends on the specific phenomenon being considered.
Video credit: NASA’s Goddard Space Flight Center/Beth Anthony (KBRwyle): Producer/Mara Johnson-Groh (Telophase): Writer/Barbara Giles (NASA/GSFC): Scientist/Genna Duberstein (ADNET): Writer/Music: “Artificial Intelligence†by Matteo Pagamici [SUISA], Max Molling [SUISA] via Universal Production Music
Wikipedia dicit:
Concerning the lunar month of approximately 29.53 days as viewed from Earth, the lunar phase or Moon phase is the shape of the Moon’s directly sunlit portion, which can be expressed quantitatively using areas or angles, or described qualitatively using the terminology of the four major phases (new moon, first quarter, full moon, last quarter) and four minor phases (waxing crescent, waxing gibbous, waning gibbous, and waning crescent).
The lunar phases gradually change over a synodic month (c. 29.53 days) as the orbital positions of the Moon around Earth, and Earth around the Sun, shift. The visible side of the Moon is variously sunlit, depending on the position of the Moon in its orbit, with the sunlit portion varying from 0% (at new moon) to 100% (at full moon).
Each of the four major lunar phases is approximately 7.4 days±19 hours (6.58–8.24 days), the variation being due to the elliptical shape of the Moon’s orbit.
There are four principal (primary, or major) lunar phases: the new moon, first quarter, full moon, and last quarter (also known as third or final quarter), when the Moon’s ecliptic longitude is at an angle to the Sun (as viewed from the center of the Earth) of 0°, 90°, 180°, and 270° respectively. Each of these phases appears at slightly different times at different locations on Earth, and tabulated times are therefore always geocentric (calculated for the Earth’s center).
Between the principal phases are intermediate phases, during which the Moon’s apparent shape is either crescent or gibbous. On average, the intermediate phases last one-quarter of a synodic month, or 7.38 days.
The term waxing is used for an intermediate phase when the Moon’s apparent shape is thickening, from new to a full moon; and waning when the shape is thinning. The duration from full moon to new moon (or new moon to full moon) varies from approximately 13 days 22+1â„2 hours to about 15 days 14+1â„2 hours.
A new moon appears highest on the summer solstice and lowest on the winter solstice. A first quarter moon appears highest on the spring equinox and lowest on the autumn equinox. A full moon appears highest on the winter solstice and lowest on the summer solstice. A last quarter moon appears highest on the autumn equinox and lowest on the spring equinox.
Credit: NASA Goddard
Wikipedia dicit:
A neutron star is the collapsed core of a massive supergiant star, which had a total mass of between 10 and 25 solar masses, possibly more if the star was especially metal-rich. Except for black holes and some hypothetical objects (e.g. white holes and quark stars), neutron stars are the smallest and densest currently known class of stellar objects. Neutron stars have a radius on the order of 10 kilometres (6 mi) and a mass of about 1.4 solar masses. They result from the supernova explosion of a massive star, combined with gravitational collapse, that compresses the core past white dwarf star density to that of atomic nuclei.
Once formed, they no longer actively generate heat and cool over time; however, they may still evolve further through collision or accretion. Most of the basic models for these objects imply that neutron stars are composed almost entirely of neutrons (subatomic particles with no net electrical charge and with slightly larger mass than protons); the electrons and protons present in normal matter combine to produce neutrons at the conditions in a neutron star. Neutron stars are partially supported against further collapse by neutron degeneracy pressure, a phenomenon described by the Pauli exclusion principle, just as white dwarfs are supported against collapse by electron degeneracy pressure. However, neutron degeneracy pressure is not by itself sufficient to hold up an object beyond 0.7 M☉ and repulsive nuclear forces play a larger role in supporting more massive neutron stars. If the remnant star has a mass exceeding the Tolman–Oppenheimer–Volkoff limit of around 2 solar masses, the combination of degeneracy pressure and nuclear forces is insufficient to support the neutron star. It continues collapsing to form a black hole. The most massive neutron star detected so far, PSR J0952–0607, is estimated to be 2.35±0.17 solar masses.
Neutron stars that can be observed are very hot and typically have a surface temperature of around 600000 K. Neutron star material is remarkably dense: a normal-sized matchbox containing neutron-star material would have a weight of approximately 3 billion tonnes, the same weight as a 0.5 cubic kilometre chunk of the Earth (a cube with edges of about 800 metres) from Earth’s surface. Their magnetic fields are between 108 and 1015 (100 million and 1 quadrillion) times stronger than Earth’s magnetic field. The gravitational field at the neutron star’s surface is about 2×1011 (200 billion) times that of Earth’s gravitational field.
Credit: NASA Goddard
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