Dark Flow

Dark flow is an astrophysical term describing a peculiar velocity of galaxy clusters. The actual measured velocity is the sum of the velocity predicted by Hubble's Law plus a small and unexplained (or dark) velocity flowing in a common direction.

According to standard cosmological models, the motion of galaxy clusters with respect to the cosmic microwave background should be randomly distributed in all directions. However, analyzing the three-year WMAP data using the kinematic Sunyaev-Zel'dovich effect, the authors of the study found evidence of a "surprisingly coherent" 600–1000 km/s flow of clusters toward a 20-degree patch of sky between the constellations of Centaurus and Vela.

The authors (Alexander Kashlinsky, F. Atrio-Barandela, D. Kocevski, and H. Ebeling) suggest that the motion may be a remnant of the influence of no-longer-visible regions of the universe prior to inflation. Telescopes cannot see events earlier than about 380,000 years after the big bang, when the universe became transparent (the Cosmic Microwave Background); this corresponds to the particle horizon at a distance of about 46 billion (4.6×10^10) light years. Since the matter causing the net motion in this proposal is outside this range, it would in a certain sense be outside our visible universe; however, it would still be in our past light cone.

The results appeared in the October 20, 2008, issue of Astrophysical Journal Letters. Since then, the authors have extended their analysis to additional clusters and the recently released WMAP five-year data.

Location

The dark flow was determined to be flowing in the direction of the Centaurus and Hydra constellations. This corresponds with the direction of the Great Attractor, which was a previous gravitational mystery originally discovered in 1973. However, the source of the Great Attractor's attraction was thought to originate from a massive cluster of galaxies called the Norma cluster, situated merely between 150-250 million light-years away. This may reveal that the source of that attraction might lie even further away, and which the Great Attractor itself is heading towards.

In a study from March 2010, Kashlinsky extended his work from 2008, by using the 5-year WMAP results rather than the 3-year results, and doubling the number of galaxy clusters observed from 700. The team also sorted the cluster catalog into four "slices" representing different distance ranges. They then examined the preferred flow direction for the clusters within each slice. While the size and exact position of this direction display some variation, the overall trends among the slices exhibit remarkable agreement. "We detect motion along this axis, but right now our data cannot state as strongly as we'd like whether the clusters are coming or going," Kashlinsky said.

The team has so far catalogued the effect as far out as 2.5 billion light-years, and hope to expand their catalog out further still to twice the current distance.


Panoramic view of galaxies beyond Milky Way, with Norma cluster & Great Attractor shown by a long blue arrow at the bottom-right in image near the disk of the Milky Way.

NASA's Goddard Space Center confirmed this could be the effects of a sibling universe or a region of space-time fundamentally different from the observable universe. Data on more than 1,000 galaxy clusters have been measured, including some as distant as 3 billion light-years. Alexander Kashlinsky claims these measurements show the universe's steady flow is clearly not a statistical fluke. Said Kashlinsky: "At this point we don't have enough information to see what it is, or to constrain it. We can only say with certainty that somewhere very far away the world is very different than what we see locally. Whether it's 'another universe' or a different fabric of space-time we don't know."

Axial Precession

In astronomy, axial precession is a gravity-induced, slow and continuous change in the orientation of an astronomical body's rotational axis. In particular, it refers to the gradual shift in the orientation of Earth's axis of rotation, which, like a wobbling top, traces out a cone in a cycle of approximately 26,000 years (called a Great or Platonic Year in astrology). The term "precession" typically refers only to this largest secular motion; other changes in the alignment of Earth's axis — nutation and polar motion — are much smaller in magnitude.

Earth's precession was historically called precession of the equinoxes because the equinoxes moved westward along the ecliptic relative to the fixed stars, opposite to the motion of the Sun along the ecliptic. This term is still used in non-technical discussions, that is, when detailed mathematics are absent. Historically, Hipparchus is credited with discovering precession of the equinoxes. The exact dates of his life are not known, but astronomical observations attributed to him by Ptolemy date from 147 BC to 127 BC.

With improvements in the ability to calculate the gravitational force between planets during the first half of the 19th century, it was recognized that the ecliptic itself moved slightly, which was named planetary precession as early as 1863, while the dominant component was named lunisolar precession. Their combination was named general precession instead of precession of the equinoxes. Lunisolar precession is caused by the gravitational forces of the Moon and Sun on Earth's equatorial bulge, causing Earth's axis to move with respect to inertial space. Planetary precession (actually an advance) is due to the small angle between the gravitational force of the other planets on Earth and its orbital plane (the ecliptic), causing the plane of the ecliptic to shift slightly relative to inertial space. Lunisolar precession is about 500 times larger than planetary precession. In addition to the Moon and Sun, the other planets also cause a small movement of Earth's axis in inertial space, making the contrast in the terms lunisolar versus planetary misleading, so in 2006 the International Astronomical Union recommended that the dominant component be renamed the precession of the equator and the minor component be renamed precession of the ecliptic, but their combination is still named general precession.

Effects

The precession of the Earth's axis has a number of observable effects. First, the positions of the south and north celestial poles appear to move in circles against the space-fixed backdrop of stars, completing one circuit in 25,771.5 years (2000 rate). Thus, while today the star Polaris lies approximately at the north celestial pole, this will change over time, and other stars will become the "north star". As the celestial poles shift, there is a corresponding gradual shift in the apparent orientation of the whole star field, as viewed from a particular position on Earth.

Secondly, the position of the Earth in its orbit around the Sun at the solstices, equinoxes, or other time defined relative to the seasons, slowly changes. For example, suppose that the Earth's orbital position is marked at the summer solstice, when the Earth's axial tilt is pointing directly towards the Sun. One full orbit later, when the Sun has returned to the same apparent position relative to the background stars, the Earth's axial tilt is not now directly towards the Sun: because of the effects of precession, it is a little way "beyond" this. In other words, the solstice occurred a little earlier in the orbit. Thus, the tropical year, measuring the cycle of seasons (for example, the time from solstice to solstice, or equinox to equinox), is about 20 minutes shorter than the sidereal year, which is measured by the Sun's apparent position relative to the stars. Note that 20 minutes per year is approximately equivalent to one year per 25,771.5 years, so after one full cycle of 25,771.5 years the positions of the seasons relative to the orbit are "back where they started". (In actuality, other effects also slowly change the shape and orientation of the Earth's orbit, and these, in combination with precession, create various cycles of differing periods; see also Milankovitch cycles. The magnitude of the Earth's tilt, as opposed to merely its orientation, also changes slowly over time, but this effect is not attributed directly to precession.)

For identical reasons, the apparent position of the Sun relative to the backdrop of the stars at some seasonally fixed time, say the vernal equinox, slowly regresses a full 360° through all twelve traditional constellations of the zodiac, at the rate of about 50.3 seconds of arc per year (approximately 360 degrees divided by 25,771.5), or 1 degree every 71.6 years.

Sedna

90377 Sedna is a trans-Neptunian object, discovered in 2003, which currently lies about three times as far from the Sun as Neptune. However, its farthest orbital distance from the Sun is estimated to be 960 astronomical units (AU), and thus it is, for the majority of its orbit, the most distant known object in the Solar System after long-period comets.

Roughly two-thirds the size of Pluto, Sedna is hypothetically large enough to be rounded by its own gravity, and thus would qualify as a dwarf planet under current definitions. However, its distance from the Sun makes determining its shape difficult. Spectroscopy has revealed that Sedna's surface composition is similar to that of some other trans-Neptunian objects, being largely a mixture of water, methane and nitrogen ices with tholins. Its surface is one of the reddest in the Solar System.

Sedna's exceptionally long and elongated orbit, taking approximately 12,000 years to complete, and distant point of closest approach to the Sun, at 76 AU, have led to much speculation as to its origin. The Minor Planet Center currently places Sedna in the scattered disc, a group of objects sent into highly elongated orbits by the gravitational influence of Neptune. However, this classification has been contested, as Sedna never comes close enough to Neptune to have been scattered by it, leading some astronomers to conclude that it is in fact the first known member of the inner Oort cloud. Others speculate that it might have been tugged into its current orbit by a passing star, perhaps one within the Sun's birth cluster, or even that it was captured from another star system. Another hypothesis suggests that its orbit may be evidence for a large planet beyond the orbit of Neptune. Astronomer Mike Brown, who co-discovered Sedna as well as the dwarf planets Eris, Haumea, and Makemake, believes it to be the most scientifically important trans-Neptunian object found to date, as understanding its peculiar orbit is likely to yield valuable information about the origin and early evolution of the Solar System.

Orbit and rotation

Barring comets, Sedna has the longest orbital period of any known object in the Solar System, calculated at between 11,800 and 12,100 years. This represents a best-fit solution, as Sedna has only been observed over a brief part of its orbital arc. Its orbit is extremely elliptical, with an aphelion estimated at 960 AU and a perihelion at about 76 AU. At its discovery it was approaching perihelion at 89.6 AU from the Sun, and was the most distant object in the Solar System yet observed. Eris was later detected by the same survey at 97 AU. Although the orbits of some long-period comets extend farther than that of Sedna, they are too dim to be discovered except when approaching perihelion in the inner Solar System. Even as Sedna nears its perihelion in late 2075 to mid 2076, the Sun would appear merely as a bright star in its sky: with an angular diameter too small to resolve as a disc, it would be only 100 times brighter than a full Moon on Earth.



When first discovered, Sedna was believed to have an unusually long rotational period (20 to 50 days). It was initially speculated that Sedna's rotation was slowed by the gravitational pull of a large binary companion, similar to Pluto's moon Charon. A search for such a satellite by the Hubble Space Telescope in March 2004 found nothing, and subsequent measurements from the MMT telescope suggest a much shorter rotation period, only about 10 hours, rather typical for bodies of its size.

Eris

Eris, formal designation 136199 Eris, is the largest known dwarf planet in the Solar System and the ninth-largest body known to orbit the Sun directly. It is approximately 2,500 kilometres in diameter and 27% more massive than Pluto.

Eris was first identified in January 2005 by a Palomar Observatory-based team led by Mike Brown, and its identity verified later that year. It is a trans-Neptunian object (TNO) native to a region of space beyond the Kuiper belt known as the scattered disc. Eris has one moon, Dysnomia; recent observations have found no evidence of further satellites. The current distance from the Sun is 96.7 AU, roughly three times that of Pluto. With the exception of some comets the pair are the most distant known natural objects in the Solar System.

Because Eris is larger than Pluto, its discoverers and NASA initially described it as the Solar System’s tenth planet. This, along with the prospect of other similarly sized objects being discovered in the future, motivated the International Astronomical Union (IAU) to define the term planet for the first time. Under a then-new IAU definition approved on August 24, 2006, Eris is a "dwarf planet" along with Pluto, Ceres, Haumea and Makemake.

Eris is named after the Greek goddess Eris, a personification of strife and discord. The name was assigned on September 13, 2006 following an unusually long period in which it was known by the provisional designation 2003 UB313, which was granted automatically by the IAU under their naming protocols for minor planets. The regular adjectival form of Eris is Eridian.

Orbit



Eris has an orbital period of 557 years, and as of 2009 lies at 96.7 astronomical units from the Sun, almost its maximum possible distance. (Its aphelion is 97.5 AU.) Eris came to perihelion between 1698 and 1699, to aphelion around 1977, and will return to perihelion around 2256[34] to 2258. Eris and its moon are currently the most distant known objects in the Solar System apart from long-period comets and space probes. However, approximately forty known TNOs, most notably 2000 OO67 and Sedna, while currently closer to the Sun than Eris, have greater average orbital distances than Eris' semimajor axis of 67.7 AU.

The Eridian orbit is highly eccentric, and brings Eris to within 37.9 AU of the Sun, a typical perihelion for scattered objects. This is within the orbit of Pluto, but still safe from direct interaction with Neptune (29.8–30.4 AU). Pluto, on the other hand, like other plutinos, follows a less inclined and less eccentric orbit and, protected by orbital resonance, can cross Neptune’s orbit. (It is possible that Eris is in a 17:5 resonance with Neptune, though further observations will be required to know for sure.[37]) Unlike the eight planets, whose orbits all lie roughly in the same plane as the Earth's, Eris' orbit is highly inclined: It is tilted at an angle of about 44 degrees to the ecliptic. In about 800 years, Eris will be closer to the Sun than Pluto for some time.

Eris currently has an apparent magnitude of 18.7, making it bright enough to be detectable to some amateur telescopes. A 200 mm telescope with a CCD can detect Eris under favorable conditions. The reason it had not been noticed until now is because of its steep orbital inclination; most searches for large outer Solar System objects concentrate on the ecliptic plane, where most bodies are found.

Eris is now in the constellation Cetus. It was in Sculptor from 1876 until 1929 and Phoenix from roughly 1840 until 1875. In 2036 it will enter Pisces and stay there until 2065, when it will enter Aries. It will then move into the northern sky, entering Perseus in 2128 and Camelopardalis (where it will reach its northernmost declination) in 2173. Because the orbit of Eris is highly inclined, it only passes through a few constellations of the traditional Zodiac.

Size, mass, and density

The diameter of Eris has been measured to be 2,397 km, give or take 100 km, using images from the Hubble Space Telescope (HST).[38][39] The size of an object depends on its absolute magnitude and the albedo (the amount of light it reflects). At a distance of 97 AU, an object with a radius of 3,000 km would have an angular size of 40 milliarcseconds, which is directly measurable with the HST; although resolving such small objects is at the very limit of Hubble's capabilities, sophisticated image processing techniques such as deconvolution can be used to measure such angular sizes fairly accurately.)

This makes Eris only 0-8% larger than Pluto, which is about 2,306 km across. It also indicates an albedo of 0.86, higher than any other large body in the Solar System other than Enceladus. It is speculated that the high albedo is due to the surface ices being replenished due to temperature fluctuations as Eris' eccentric orbit takes it closer and farther from the Sun.

In 2007, a series of observations of the largest trans-Neptunian objects with the Spitzer Space Telescope gave an estimate of Eris's diameter of 2,600 (+400; -200) km.[8] The Spitzer and Hubble estimates overlap in the range of 2,400-2,500 km, 4-8% larger than Pluto.

The mass of Eris can be calculated with much greater precision. Based on the currently accepted value for Dysnomia's period, 15.774 days, Eris is 27 percent more massive than Pluto.

Lunokhod

Lunokhod 1 (Луноход, moon walker in Russian) was the first of two unmanned lunar rovers landed on the Moon by the Soviet Union as part of its Lunokhod program. The spacecraft which carried Lunokhod 1 was named Luna 17. Lunokhod was the first roving remote-controlled robot to land on another world.

Rover description

Lunokhod 1 was a lunar vehicle formed of a tub-like compartment with a large convex lid on eight independently powered wheels. Its length was 2.3 metres. Lunokhod was equipped with a cone-shaped antenna, a highly directional helical antenna, four television cameras, and special extendable devices to impact the lunar soil for soil density and mechanical property tests. An X-ray spectrometer, an X-ray telescope, cosmic ray detectors, and a laser device were also included. The vehicle was powered by batteries which were recharged during the lunar day by a solar cell array mounted on the underside of the lid. During the lunar nights, the lid was closed and a Polonium-210 heat source kept the internal components at operating temperature. Lunokhod was intended to operate through three lunar days (approximately 3 Earth months) but actually operated for eleven lunar days.

Luna 17 was launched on November 10, 1970 at 14:44:01 UTC. After reaching earth parking orbit, the final stage of Luna 17's launching rocket fired to place it into a trajectory towards the Moon (1970-11-10 at 14:54 UTC). After two course correction maneuvers (on November 12 and 14), it entered lunar orbit on November 15, 1970 at 22:00 UTC.

During its 322 Earth days of operations, Lunokhod traveled 10540 metres and returned more than 20000 TV images and 206 high-resolution panoramas. In addition, Lunokhod 1 performed twenty-five soil analysis with its RIFMA x-ray fluorescence spectrometer and used its penetrometer at 500 different locations.

Phoenix

MRO (Mars Reconnaissance Orbiter) imaged Phoenix suspended from its parachute during descent through the Martian atmosphere.

phoenix.lpl.arizona.edu



Phoenix is a robotic spacecraft on a space exploration mission on Mars under the Mars Scout Program. The scientists conducting the mission are using instruments aboard the Phoenix lander to search for environments suitable for microbial life on Mars, and to research the history of water there. The multi-agency program is headed by the Lunar and Planetary Laboratory at the University of Arizona, under the direction of NASA's Jet Propulsion Laboratory. The program is a partnership of universities in the United States, Canada, Switzerland, Denmark, Germany, the United Kingdom, NASA, the Canadian Space Agency, the Finnish Meteorological Institute, Lockheed Martin Space Systems, MacDonald Dettwiler & Associates (MDA) and other aerospace companies.



Phoenix is the sixth successful landing on Mars, out of twelve total attempts (seven of which were American). It is the third successful static lander and the first since Viking 2, and as of 2008 the most recent spacecraft to land successfully on Mars. It is also the first successful landing on a polar region of Mars.

Antares

Antares is a star in the Milky Way galaxy and the sixteenth brightest star in the nighttime sky (sometimes listed as fifteenth brightest, if the two brighter components of the Capella quadruple star system are counted as one star). Along with Aldebaran, Spica, and Regulus it is one of the four brightest stars near the ecliptic. The similarly colored Aldebaran lies almost directly opposite Antares in the Zodiac.

Antares is a class M supergiant star, with a diameter of approximately 700 times that of the sun; if it were placed in the centre of our solar system, its outer surface would lie between the orbits of Mars and Jupiter. Antares is approximately 600 light years from our solar system. Its visual luminosity is about 10,000 times that of the Sun, but because the star radiates a considerable part of its energy in the infrared part of the spectrum, the bolometric luminosity equals roughly 65,000 times that of the Sun. The mass of the star is calculated to be 15 to 18 solar masses. Its large size and relatively small mass give Antares a very low average density.

The best time to view Antares is on or around May 31 of each year, when the star is at "opposition" to the Sun. At this time, Antares rises at dusk and sets at dawn, and is thus in view all night (depending on your position on Earth). For approximately two to three weeks on either side of November 30, Antares is not visible at all, being lost in the Sun's glare; this period of invisibility is longer in the Northern Hemisphere than in the Southern Hemisphere, since the star's declination is significantly south of the celestial equator.

Rosetta (ESA)

Ariane 5 Launch of Rosetta spacecraft

Rosetta is a European Space Agency-led robotic spacecraft mission launched in 2004 intended to study the comet 67P/Churyumov-Gerasimenko. Rosetta consists of two main elements: the Rosetta space probe and the Philae lander. The probe is named after the Rosetta Stone, as it is hoped the mission will help unlock the secrets of how our solar system looked before planets formed. The lander is named after the Nile island Philae where an obelisk was found that helped decipher the Rosetta Stone.


3-D Reconstruction of Comet 67P/Churyumov-Gerasimenko's nucleus from Hubble telescope observations

Timeline for the mission after its launch:

* First Earth fly-by (March 2005)
* February 25, 2007 Mars fly-by
* November 13, 2007 Second Earth fly-by
* September 5, 2008 - flyby of asteroid 2867 Šteins
* Third Earth fly-by (November 2009)
* July 10, 2010 - flyby of asteroid 21 Lutetia
* Deep-space hibernation (May 2011 - January 2014)
* Comet approach (January-May 2014)
* Comet mapping / Characterisation (August 2014)
* Landing on the comet (November 2014)
* Escorting the comet around the Sun (November 2014 - December 2015)

Einstein Ring

In observational astronomy an Einstein ring is the deformation of the light from a source into a ring through gravitational deflection of the source's light by a lens. This occurs when the source, lens and observer are all aligned.



Gravitational lensing is a result from Albert Einstein's theory of General relativity. Instead of light from a source traveling in a straight line (in three dimensions), it is bent by the presence of a massive body, which distorts spacetime. An Einstein Ring is a special case of gravitational lensing, caused by the exact alignment of the source, lens and observer. This results in a symmetry around the lens, causing a ring-like structure.

Comet Shoemaker-Levy 9

Hubble Space Telescope image of Comet Shoemaker-Levy 9, taken on May 17, 1994.

Comet Shoemaker-Levy 9 (SL9, formally designated D/1993 F2) was a comet that collided with Jupiter in 1994, providing the first direct observation of the collision of two solar system objects, not including collisions involving Earth. This generated a large amount of coverage in the popular media, and SL9 was closely observed by astronomers worldwide. The comet provided many revelations about Jupiter and its atmosphere and highlighted Jupiter's role in reducing space debris in the inner solar system.



The comet was discovered by astronomers Carolyn and Eugene M. Shoemaker and David Levy. Shoemaker-Levy 9 was located on the night of March 24, 1993, in a photograph taken with the 0.4-metre Schmidt telescope at the Mount Palomar Observatory in California. It was the first comet observed to be orbiting a planet rather than the Sun.



SL9 was in pieces ranging in size up to 2 kilometres in diameter, and is believed to have been pulled apart by Jupiter's tidal forces during a close encounter in July 1992. These fragments collided with Jupiter's southern hemisphere between July 16 and July 22, 1994, at a speed of approximately 60 kilometres per second. The prominent scars from the impacts could be seen on Jupiter for many months after the impact, and observers described them as more easily visible than the Great Red Spot.



One of the surprises of the impacts was the small amount of water revealed compared to prior predictions. Before the impact, models of Jupiter's atmosphere had indicated that the break-up of the largest fragments would occur at atmospheric pressures of anywhere from 300 kilopascals to a few megapascals (from three to a few tens bar), and most astronomers expected that the impacts would penetrate a hypothesised water-rich layer underneath the clouds.

Astronomers did not observe large amounts of water following the collisions, and later impact studies found that fragmentation and destruction of the cometary fragments in an 'airburst' probably occurred at much higher altitudes than previously expected, with even the largest fragments being destroyed when the pressure reached 250 kPa (2.5 bar), well above the expected depth of the water layer. The smaller fragments were probably destroyed before they even reached the cloud layer.

The visible scars from the impacts could be seen on Jupiter for many months after the impact. They were extremely prominent, and observers described them as more easily visible even than the Great Red Spot. A search of historical observations revealed that the spots were probably the most prominent transient features ever seen on the planet, and that while the Great Red Spot is notable for its striking colour, no spots of the size and darkness of those caused by the SL9 impacts have ever been recorded before.

Spectroscopic observers found that ammonia and carbon sulfide persisted in the atmosphere for at least fourteen months after the collisions, with a considerable amount of ammonia being present in the stratosphere as opposed to its normal location in the troposphere.

Counterintuitively, the atmospheric temperature dropped to normal levels much more quickly at the larger impact sites than at the smaller sites: at the larger impact sites, temperatures were elevated over a region 15,000–20,000 km wide, but dropped back to normal levels within a week of the impact. At smaller sites, temperatures 10 K higher than the surroundings persisted for almost two weeks. Global stratospheric temperatures rose immediately after the impacts, then fell to below pre-impact temperatures 2–3 weeks afterwards, before rising slowly to normal temperatures.

LIGO and EGO

Laser Interferometer Gravitational-Wave Observatory

LIGO stands for Laser Interferometer Gravitational-Wave Observatory. Cofounded in 1992 by Kip Thorne and Ronald Drever of Caltech and Rainer Weiss of MIT, LIGO is a joint project between scientists at MIT and Caltech. It is sponsored by the National Science Foundation (NSF). At the cost of $365 million (in 2002 USD), it was the largest and most ambitious project ever funded by NSF (and still is as of 2007). The international LIGO Scientific Collaboration (LSC) is a growing group of researchers, some 400 individuals at roughly 40 institutions, working to analyze the data from LIGO and other detectors, and working toward more sensitive future detectors.


Control Center

LIGO's mission is to directly observe gravitational waves of cosmic origin. These waves were first predicted by Einstein's Theory of General Relativity in 1916, when the technology necessary for their detection did not yet exist. Gravitational waves were indirectly confirmed to exist when observations were made of the binary pulsar PSR 1913+16, for which the Nobel Prize was awarded to Hulse and Taylor in 1993.

Direct detection of gravitational waves has long been sought, for it would open up a new branch of astronomy to complement electromagnetic telescopes and neutrino observatories. Joseph Weber pioneered the effort to detect gravitational waves in the 1960s through his work on resonant mass bar detectors.Bar detectors continue to be used at six sites worldwide. By the 1970s, scientists including Rainer Weiss realized the applicability of laser interferometry to gravitational wave measurements.

In August 2002, LIGO began its search for cosmic gravitational waves. Emissions of gravitational waves are expected from binary systems (collisions and coalescences of neutron stars or black holes), supernova of massive stars (which form neutron stars and black holes), rotations of neutron stars with deformed crusts, and the remnants of gravitational radiation created by the birth of the universe. The observatory may in theory also observe more exotic currently hypothetical phenomena, such as gravitational waves caused by oscillating cosmic strings or colliding domain walls. Since the early 1990s, physicists have believed that technology is at the point where detection of gravitational waves—of significant astrophysical interest—is possible.





The European Gravitational Observatory

The European Gravitational Observatory or EGO is located in the countryside near Pisa in the Commune of Cascina. In order to ensure the long term scientific exploitation of the VIRGO interferometric antenna for gravitational waves detection as well as to foster European collaboration in this upcoming field, the VIRGO funding institutions (CNRS for France and INFN for Italy) have created a consortium called EGO (European Gravitational Observatory).

VIRGO is a 3 kilometer interferometer built through a French-Italian collaboration. This collaboration involves 11 laboratories in France and Italy and more than 150 scientists.

EGO is established under the Italian law. Its governing body is the Council composed of six members nominated by the funding institutions. The Council appoints a Director who is the legal representative and chief executive of EGO. The Scientific and Technical Advisory Committee advises the Council on scientific and technical activities carried out by the Consortium. It is composed of up to ten scientific personalities.

Herbig-Haro Objects

Herbig-Haro object HH47, imaged by the Hubble Space Telescope. The scale bar represents 1000 Astronomical Units, equivalent to about 20 times the size of our solar system, or 1000 times the distance from the Earth to the Sun

Herbig-Haro objects are small patches of nebulosity associated with newly-born stars, and are formed when gas ejected by young stars collides with clouds of gas and dust nearby at speeds of several hundred kilometres per second. Herbig-Haro objects are ubiquitous in star-forming regions, and several are often seen around a single star, aligned along its rotational axis. HH objects are transient phenomena, lasting only a few thousand years at most. They can evolve visibly over quite short timescales as they move rapidly away from their parent star into the gas clouds in interstellar space (the interstellar medium or ISM). Hubble Space Telescope observations reveal complex evolution of HH objects over a few years, as parts of them fade while others brighten as they collide with clumpy material in the interstellar medium. The objects were first observed in the late 19th century by Sherburne Wesley Burnham, but were not recognised as being a distinct type of emission nebula until the 1940s. The first astronomers to study them in detail were George Herbig and Guillermo Haro, after whom they have been named. Herbig and Haro were working independently on studies of star formation when they first analysed Herbig-Haro objects, and recognised that they were a by-product of the star formation process.

Images taken over five years reveal the motion of material in HH object HH47.

Over 400 individual HH objects or groups are now known. They are ubiquitous in star-forming H II regions, and are often found in large groups. They are typically observed near Bok globules (dark nebulae which contain very young stars) and often emanate from them. Frequently, several HH objects are seen near a single energy source, forming a string of objects along the line of the polar axis of the parent star.

The number of known HH objects has increased rapidly over the last few years, but is still thought to be a very small proportion of the total number existing in our galaxy. Estimates suggest that up to 150,000 exist, the vast majority of which are too far away to be resolved with current technological capabilities. Most HH objects lie within 0.5 parsecs of their parent star, with very few found more than 1 pc away. However, some are seen several parsecs away, perhaps implying that the interstellar medium is not very dense in their vicinity, allowing them to travel further from their source before dispersing.

Vega

A mid-infrared image of the debris disk around Vega. Spitzer Space Telescope/NASA.

Vega is the brightest star in the constellation Lyra, the fifth brightest star in the night sky and the second brightest star in the northern celestial hemisphere, after Arcturus. It is a relatively nearby star at only 25.3 light years from Earth, and, together with Arcturus and Sirius, one of the most luminous stars in the Sun's neighborhood.

Vega has been extensively studied by astronomers, leading it to be termed, "arguably the next most important star in the sky after the Sun". Historically, Vega served as the pole star at about 12,000 BCE and will do so again at around 14,000 CE. Vega was the first star, other than the Sun, to have its photograph taken and the first to have its spectrum photographed. It was also one of the first stars to have its distance estimated through parallax measurements. Vega has served as the baseline for calibrating the photometric brightness scale, and was one of the stars used to define the mean values for the UBV photometric system.

This star is relatively young when compared to the Sun. It has an unusually low abundance of the elements that have a higher atomic numbers than helium. Vega is also a suspected variable star that may vary slightly in magnitude in a periodic manner. It is rotating rapidly with a velocity of 274 km/s at the equator. This is causing the equator to bulge outward because of centrifugal effects, and, as a result, there is a variation of temperature across the star's photosphere that reaches a maximum at the poles. From the Earth, Vega is being observed from the direction of one of these poles.

Based upon an excess emission of infrared radiation, Vega has a circumstellar disk of dust. This dust is likely the result of collisions between objects in an orbiting debris disk, which is analogous to the Kuiper belt in the Solar System. Stars that display an infrared excess because of dust emission are termed Vega-like stars. Irregularities in Vega's disk also suggest the presence of at least one planet, likely to be about the size of Jupiter, in orbit around Vega.

Charon

Charon NASA

Charon discovered in 1978, is, depending on the definition employed, either the largest moon of Pluto or one member of a double dwarf planet with Pluto being the other member. With the discovery in 2005 of two other moons of Pluto (Nix and Hydra), Charon is now also referred to as Pluto I. The New Horizons mission is scheduled to visit Charon and Pluto in July 2015.


Distant Pluto and Charon (Hubble Space Telescope)

Charon appears to be covered by water ice, which differs from Pluto's surface of frozen nitrogen, methane, and carbon dioxide. One theory is that the materials that formed Charon were blasted out of Pluto in a collision. That's very similar to the way in which our own moon is thought to have been created.

Johann Carl Friedrich Gauss (1777-1855)

Johann Carl Friedrich Gauss (30 April 1777 – 23 February 1855) was a German mathematician and scientist who contributed significantly to many fields, including number theory, statistics, analysis, differential geometry, geodesy, electrostatics, astronomy, and optics. Sometimes known as "the prince of mathematicians" and "greatest mathematician since antiquity", Gauss had a remarkable influence in many fields of mathematics and science and is ranked as one of history's most influential mathematicians.

Gauss was a child prodigy, of whom there are many anecdotes pertaining to his astounding precocity while a mere toddler, and made his first ground-breaking mathematical discoveries while still a teenager. He completed Disquisitiones Arithmeticae, his magnum opus, at the age of 21 (1798), though it would not be published until 1801. This work was fundamental in consolidating number theory as a discipline and has shaped the field to the present day.


Error Function (In mathematics, the error function (also called the Gauss error function) is a non-elementary function which occurs in probability, statistics and partial differential equations.)

Chandra X-ray Observatory

Chandra X-ray Observatory

NASA's Chandra X-ray Observatory, which was launched and deployed by Space Shuttle Columbia on July 23, 1999, is the most sophisticated X-ray observatory built to date.


M87 Core; about 50 million light years

The Instruments:

The Science Instrument Module (SIM) holds the two focal plane instruments, the Advanced CCD Imaging Spectrometer (ACIS) and the High Resolution Camera (HRC), moving whichever is called for into position during an observation.

ACIS consists of 10 CCD chips and provides images as well as spectral information of the object observed. It operates in the range of 0.2 - 10 keV. HRC has two micro-channel plate components and images over the range of 0.1 - 10 keV. It also has a time resolution of 16 microseconds. Both of these instruments can be used on their own or in conjunction with one of the observatory's two transmission gratings.

The transmission gratings, which swing into the optical path behind the mirrors, provide Chandra with high resolution spectroscopy. The High Energy Transmission Grating Spectrometer (HETGS) works over 0.4 - 10 keV and has a spectral resolution of 60-1000. The Low Energy Transmission Grating Spectrometer (LETGS) has a range of 0.09 - 3 keV and a resolution of 40-2000.


G292.0+1.8; about 20,000 light years; 142 hours of observation

Latest Discoveries:

# X-ray emissions from materials falling from a protoplanetary disc into a star.
# Hubble constant measured to be 76.9 km/s/Mpc using Sunyaev-Zel'dovich effect.
# 2006 Chandra found strong evidence that dark matter exists by observing supercluster collision
# 2006 X-ray emitting loops, rings and filaments discovered around a supermassive black hole within Messier 87 imply the presence of pressure waves, shock waves and sound waves. The evolution of Messier 87 may have been dramatically affected.
# Observations of the Bullet cluster put limits on the cross-section of the self-interaction of dark matter.

Spitzer Space Telescope

Spitzer NASA Official

Spitzer Space Telescope Wikipedia

Lyman Spitzer

The Spitzer Space Telescope (formerly the Space Infrared Telescope Facility or SIRTF) is an infrared space observatory, the fourth and final of NASA's Great Observatories.

The time frame of the mission will be a minimum of 2.5 years, with 5 or more optimal. In keeping with NASA tradition, the telescope was renamed after successful demonstration of operation, on December 18, 2003. Unlike most telescopes which are named after famous deceased astronomers by a board of scientists, the name for SIRTF was obtained from a contest open to the general public (to the delight of science educators).


Image of Andromeda Galaxy (M31) taken by Spitzer in infrared, MIPS, 24 micrometers.


The name chosen was that of Dr. Lyman Spitzer, Jr., the first to propose placing telescopes in space, in the mid-1940s.

The US$ 800 million Spitzer was launched on Monday 25 August 2003 at 1:35:39 (EDT) from Cape Canaveral Air Force Station on a Delta II 7920H ELV rocket. It follows a rather unusual orbit, heliocentric instead of geocentric, following earth in its orbit, and drifting away from Earth at approximately 0.1 astronomical unit per year (a so-called "earth-trailing" orbit). The primary mirror is 85 cm in diameter, f/12 (i. e. the focal length is 12 times the diameter of the primary mirror) and made of beryllium and cooled to 5.5 K. The satellite contains three instruments that will allow it to perform imaging and photometry from 3 to 180 micrometers, spectroscopy from 5 to 40 micrometers, and spectrophotometry from 5 to 100 micrometers.

Instruments:

* IRAC (Infrared Array Camera), an infrared camera which operates simultaneously on four wavelengths (3.6 µm, 4.5 µm, 5.8 µm and 8 µm). The resolution is 256 × 256 pixels.

* IRS (Infrared Spectrograph), an infrared spectrometer with four sub-modules which operate at the wavelengths 5.3-14 µm (low resolution), 10-19.5 µm (high resolution), 14-40 µm (low resolution), and 19-37 µm (high resolution).

* MIPS (Multiband Imaging Photometer for Spitzer), three detector arrays in the far infrared (128 × 128 pixels at 24 µm, 32 × 32 pixels at 70 µm, 2 × 20 pixels at 160 µm)

Triton

Nasa : Neptune : Triton

Triton is the largest moon of Neptune, with a diameter of 2,700 kilometers (1,680 miles). It was discovered by William Lassell, a British astronomer, in 1846 scarcely a month after Neptune was discovered. Triton is colder than any other measured object in the Solar System with a surface temperature of -235° C (-391° F). It has an extremely thin atmosphere. Nitrogen ice particles might form thin clouds a few kilometers above the surface. The atmospheric pressure at Triton's surface is about 14 microbars, 1/70,000th the surface pressure on Earth.



Triton is the only large satellite in the solar system to circle a planet in a retrograde direction - in a direction opposite to the rotation of the planet. It also has a density of about 2.066 grams per cubic centimeter. This means Triton contains more rock in its interior than the icy satellites of Saturn and Uranus do. The relatively high density and the retrograde orbit has led some scientists to suggest that Triton may have been captured by Neptune as it traveled through space several billion years ago. If that is the case, tidal heating could have melted Triton in its originally eccentric orbit, and the satellite might even have been liquid for as long as one billion years after its capture by Neptune.



It is one of only three objects in the Solar System known to have a nitrogen-dominated atmosphere (the others are Earth and Saturn's giant moon, Titan). Triton has the coldest surface known anywhere in the Solar System (38 K, about -391° Farenheit); it is so cold that most of Triton's nitrogen is condensed as frost, making it the only satellite in the Solar System known to have a surface made mainly of nitrogen ice. The pinkish deposits constitute a vast south polar cap believed to contain methane ice, which would have reacted under sunlight to form pink or red compounds. The dark streaks overlying these pink ices are believed to be an icy and perhaps carbonaceous dust deposited from huge geyser-like plumes, some of which were found to be active during the Voyager 2 flyby. The bluish-green band visible in this image extends all the way around Triton near the equator; it may consist of relatively fresh nitrogen frost deposits. The greenish areas includes what is called the cataloupe terrain, whose origin is unknown, and a set of 'cryovolcanic' landscapes apparently produced by icy-cold liquids (now frozen) erupted from Triton's interior.



Neptune and Triton three days after the flyby of Voyager 2.

MESSENGER (NASA)

MESSENGER NASA Official

The MErcury Surface, Space ENvironment, GEochemistry and Ranging (or MESSENGER for short) is a NASA mission, launched August 3, 2004, designed to study the characteristics and environment of Mercury from orbit. Specifically, the scientific objectives of the mission are to characterize the chemical composition of Mercury's surface, the geologic history, the nature of the magnetic field, the size and state of the core, the volatile inventory at the poles, and the nature of Mercury's exosphere and magnetosphere over a nominal orbital mission of one Earth year. The mission will be the first to return to Mercury in over 35 years — the only previous probe to visit Mercury was Mariner 10, which completed its mission in March, 1975. MESSENGER will offer several vast improvements in scanning ability, with cameras that can resolve surface features down to just 60 feet across (18 meters) compared to the one mile (1.61 kilometer) resolution offered by Mariner 10. MESSENGER will also be the first probe to image the entire planet; Mariner 10 was only able to observe one hemisphere that was lit during its flybys.



In addition to being an acronym, MESSENGER was chosen as the probe's name because Mercury was the messenger of the gods in Roman mythology.

Solar System Simulator

Solar System Simulator



See where the planets, spacecrafts are...

Io and Jupiter

Here Io is seen just passing in front of Jupiter, as seen from the Galileo spacecraft on the day of its arrival at Jupiter. Galileo has since flown by the other three Galilean satellites of Jupiter (Europa, Ganymede, and Callisto) during its orbital tour of the Jovian system.