Astronomy facts

November 10, 2010, 7:28 AM CT

A Galactic Collision in Action

Atoms-for-Peace is the curious name given to a pair of interacting and merging galaxies that lie around 220 million light-years away in the constellation of Aquarius. It is also known as NGC 7252 and Arp 226 and is just bright enough to be seen by amateur astronomers as a very faint small fuzzy blob. This very deep image was produced by ESO's Wide Field Imager on the MPG/ESO 2.2-metre telescope at ESO's La Silla Observatory in Chile.

A galaxy collision is one of the most important processes influencing how our Universe evolves, and studying them reveals important clues about galactic ancestry. Luckily, such collisions are long drawn-out events that last hundreds of millions of years, giving astronomers plenty of time to observe them.

This picture of Atoms-for-Peace represents a snapshot of its collision, with the chaos in full flow, set against a rich backdrop of distant galaxies. The results of the intricate interplay of gravitational interactions can be seen in the shapes of the tails made from streams of stars, gas and dust. The image also shows the incredible shells that formed as gas and stars were ripped out of the colliding galaxies and wrapped around their joint core. While much material was ejected into space, other regions were compressed, sparking bursts of star formation. The result was the formation of hundreds of very young star clusters, around 50 to 500 million years old, which are speculated to be the progenitors of globular clusters......... Posted by: Sean      Read more         Source

October 18, 2010, 7:39 AM CT

How to Weigh a Star Using a Moon

How do astronomers weigh a star that's trillions of miles away and way too big to fit on a bathroom scale? In most cases they can't, eventhough they can get a best estimate using computer models of stellar structure.

New work by astrophysicist David Kipping says that in special cases, we can weigh a star directly. If the star has a planet, and that planet has a moon, and both of them cross in front of their star, then we can measure their sizes and orbits to learn about the star.

"I often get asked how astronomers weigh stars. We've just added a new technique to our toolbox for that purpose," said Kipping, a predoctoral fellow at the Harvard-Smithsonian Center for Astrophysics.

Astronomers have found more than 90 planets that cross in front of, or transit, their stars. By measuring the amount of starlight that's blocked, they can calculate how big the planet is relative to the star. But they can't know exactly how big the planet is unless they know the actual size of the star. Computer models give a very good estimate but in science, real measurements are best.

Kipping realized that if a transiting planet has a moon big enough for us to see (by also blocking starlight), then the planet-moon-star system could be measured in a way that lets us calculate exactly how large and massive all three bodies are......... Posted by: Sean      Read more         Source

January 7, 2009, 11:45 PM CT

A Cosmic Radio Mystery

Listening to the early universe just got harder. A team led by Alan Kogut of NASA's Goddard Space Flight Center in Greenbelt, Md., today announced the discovery of cosmic radio noise that booms six times louder than expected.

The finding comes from a balloon-borne instrument named ARCADE, which stands for the Absolute Radiometer for Cosmology, Astrophysics, and Diffuse Emission. In July 2006, the instrument launched from NASA's Columbia Scientific Balloon Facility in Palestine, Texas, and flew to an altitude of 120,000 feet, where the atmosphere thins into the vacuum of space.

ARCADE's mission was to search the sky for heat from the first generation of stars. Instead, it found a cosmic puzzle.

"The universe really threw us a curve," Kogut says. "Instead of the faint signal we hoped to find, here was this booming noise six times louder than anyone had predicted." Detailed analysis ruled out an origin from primordial stars or from known radio sources, including gas in the outermost halo of our own galaxy. The source of this cosmic radio background remains a mystery.

A number of objects in the universe emit radio waves. In 1931, American physicist Karl Jansky first detected radio static from our own Milky Way galaxy. Similar emission from other galaxies creates a background hiss of radio noise......... Posted by: Sean      Read more         Source

November 18, 2007, 9:20 PM CT

A new window on the universe

Using new tools to look at the universe, says Patrick Brady, often has led to discoveries that change the course of science. History is full of examples.

Galileo was the first person to use the telescope to view the cosmos, says Brady, a UWM professor of physics. His observations with the new technology led to the discovery of moons orbiting Jupiter and lent support to the heliocentric model of the solar system.

Just such an opportunity exists today with a unique observatory that is scanning the skies, searching for one of Einsteins greatest predictions gravitational waves.

Gravitational waves are produced when massive objects in space move violently. The waves carry the imprint of the events that cause them. Researchers already have indirect evidence that gravitational waves exist, but have not directly detected them.

UWM researchers, backed by considerable funding from the National Science Foundation, are taking a leadership role in the quest.

It is an epic undertaking involving about 500 researchers worldwide, including Brady and other members of UWMs Center for Cosmology and Gravitation: associate professors Alan Wiseman and Jolien Creighton, and assistant professor Xavier Siemens.

Two UWM adjunct physicists, who work at the Max Planck Institute in Gera number of, also are involved former UWM professor Bruce Allen and scientist Maria Alessandra Papa......... Posted by: Sean      Read more         Source

October 21, 2007, 10:03 PM CT

Selecting Next Mars Rover Landing Site

Researchers scouting potential landing sites for NASA's next Mars rover mission are using new data from a powerful mineral-mapping camera to narrow the site selection.

When NASA Mars Program officials and members of the Mars science community gather in California next week to pare down the list of candidate landing sites for the 2009 Mars Science Laboratory (MSL), they can refer to 125 new images from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM). The images and accompanying analysis products are available on the CRISM Web site at http://crism.jhuapl.edu/msl_landing_sites/.

Built and operated by the Johns Hopkins University Applied Physics Laboratory (APL), CRISM is one of six science instruments on NASA's Mars Reconnaissance Orbiter, currently circling the planet.

"Since MSL will assess whether Mars ever had an environment capable of supporting life, it will have to land in an area with a mineral record indicative of past water," says Dr. Scott Murchie, CRISM principal investigator from APL. "CRISM is critical to the selection process because it is the only instrument on MRO with the spectral power to 'see' the chemical makeup of the rocks".

One of CRISM's main mission objectives is to find and investigate areas that were wet long enough to leave a mineral signature. Offering greater capability to map spectral variations than any similar instrument sent to another planet, CRISM can read 544 "colors" of reflected sunlight to detect minerals in the surface......... Posted by: Sean      Read more         Source

August 26, 2007, 10:45 AM CT

First Look At Uranus's Rings As They Swing Edge-on To Earth

As the rings of Uranus swing edge-on to Earth - a short-lived view we get only once every 42 years - astronomers observing the event are getting an unprecedented, glare-free view of the rings and the fine dust that permeates them.

The rings were discovered in 1977, so this is the first opportunity astronomers have had to observe a Uranus ring crossing and perhaps to discover a new moon or two.

While the Keck II telescope and the Hubble Space Telescope have been looking at the planet for years in anticipation of this event, ground-based telescopes in Chile and southern California have targeted the planet during the actual ring crossing.

Based on the Keck observations, a team of astronomers led by Imke de Pater of University of California, Berkeley, reports Thursday, Aug. 23 in Science Express, the online edition of Science magazine, that the rings of micron-sized dust have changed significantly since the Voyager 2 spacecraft photographed the Uranus system 21 years ago. She will discuss the results during a talk August 23 at the European Planetary Science Congress 2007 meeting in Potsdam, Gera number of.

The inner rings are much more prominent than expected, revealing material in otherwise empty regions of the system of rings.

"People tend to think of the rings as unchanging, but our observations show that not to be the case," said de Pater, a UC Berkeley professor of astronomy. "There are a lot of forces acting on small dust grains, so it is not that crazy to find that the arrangement of rings has changed"......... Posted by: Sean      Read more         Source

July 4, 2007, 4:56 AM CT

The Origin Of Galaxies

The Origin of Galaxies remains one of the big questions in astrophysics, primarily because births of the first galaxies is largely hidden by (astrophysical) dust, tiny fragments of solid material in interstellar space. This dust hides the fundamental processes responsible for galaxy formation from traditional optical telescopes, as much of the optical light generated by the stars forming in the first galaxies is absorbed by the dust. However, this light is then re-radiated at longer wavelengths, mostly in the sub-millimetre (sub-mm) and far-infrared (far-IR) part of the electromagnetic spectrum.

Three new (or renewed) telescopes will largely provide European astronomers with data in the sub-mm and far-IR wavebands: ESA will soon launch the Herschel Space Observatory (HSO), and SCUBA-2 will be fully operational on the renewed James Clark Maxwell Telescope (JCMT). Also, within the next few years the Atacama Large Millimetre Array (ALMA) will start to come into operation. Located at 5500 metres in the Atacama desert in Chile, ALMA will be an array of 64 telescopes designed for high-resolution observations in the submm waveband. It is the most expensive ground-based project ever. The HSO is also a major European investment (about 1 billion Euros), but is a special case in that the HSO will have a time-limit to its operations, requiring careful planning of the observations......... Posted by: Sean      Read more         Source

June 20, 2007, 11:03 AM CT

Planetary And Extrasolar Planet Atmospheres

The world is abuzz with the discovery of an extrasolar, Earth-like planet around the star Gliese 581 that is relatively close to our Earth at 20 light years away in the constellation Libra.

Bruce Fegley, Jr., Ph.D., professor of earth and planetary sciences in Arts & Sciences at Washington University in St. Louis, has worked on computer models that can provide hints to what comprises the atmosphere of such planets and better-known celestial bodies in our own solar system.

New computer models, from both Earth-based spectroscopy and space mission data, are providing space researchers compelling evidence for a better understanding of planetary atmospheric chemistry. Recent findings suggest a trend of increasing water content in going from Jupiter (depleted in water), to Saturn (less enriched in water than other volatiles), to Uranus and Neptune, which have large water enrichments.

"The farther out you go in the solar system, the more water you find," said Fegley.

Fegley provided an overview of comparative planetary atmospheric chemistry at the 233rd American Chemical Society National Meeting, held March 25-29, 2007, in Chicago. Fegley and Katharina Lodders-Fegley, Ph.D., research associate professor of earth and planetary sciences, direct the university's Planetary Chemistry Laboratory......... Posted by: Sean      Read more         Source

May 10, 2007, 10:22 PM CT

Hyper-accurate clocks: the beating heart of Galileo

Travellers have relied on accurate timekeeping for navigation since the development of the marine chronometer in the eighteenth century. Galileo, Europe's twenty-first century navigation system, also relies on clocks - but they are millions of times more accurate than those earlier timepieces.

The operational Galileo satellites will carry two types of clocks - passive hydrogen masers and rubidium atomic frequency standards. Each satellite will be equipped with two hydrogen masers, one of which will be the primary reference for generating the navigation signals, with the other as a cold (non-operating) spare.

Every operational satellite will also carry two rubidium clocks, one of which will be a hot (permanently running) backup for the operational hydrogen maser, instantly taking over should the maser fail and allowing signal generation to continue uninterrupted. The second rubidium clock will act as a cold spare.

GIOVE-A, the Galileo in-orbit verification satellite that is currently in service, carries two rubidium clocks - one operational and one cold spare. GIOVE-B, which is projected to enter service later this year, will carry one hydrogen maser and two rubidium clocks, one hot and one cold spare. The GIOVE-A2 satellite, which will be ready for launch in the second half of 2008, will carry a similar timekeeping payload to GIOVE-A, but will transmit additional navigation signals......... Posted by: Sean      Read more         Source

March 15, 2007, 9:20 PM CT

Global 'sunscreen' has likely thinned

A new NASA study has observed that an important counter-balance to the warming of our planet by greenhouse gases sunlight blocked by dust, pollution and other aerosol particles appears to have lost ground.

The thinning of Earths "sunscreen" of aerosols since the early part of 1990s could have given an extra push to the rise in global surface temperatures. The finding, published recently in the journal Science, may lead to an improved understanding of recent climate change. In a related study published last week, researchers observed that the opposing forces of global warming and the cooling from aerosol-induced "global dimming" can occur at the same time.

"When more sunlight can get through the atmosphere and warm Earth's surface, you're going to have an effect on climate and temperature," said lead author Michael Mishchenko of NASA's Goddard Institute for Space Studies (GISS), New York. "Knowing what aerosols are doing globally gives us an important missing piece of the big picture of the forces at work on climate".

The study uses the longest uninterrupted satellite record of aerosols in the lower atmosphere, a unique set of global estimates funded by NASA. Researchers at GISS created the Global Aerosol Climatology Project by extracting a clear aerosol signal from satellite measurements originally designed to observe clouds and weather systems that date back to 1978. The resulting data show large, short-lived spikes in global aerosols caused by major volcanic eruptions in 1982 and 1991, but a gradual decline since about 1990. By 2005, global aerosols had dropped as much as 20 percent from the relatively stable level between 1986 and 1991......... Posted by: Sean      Read more         Source

March 5, 2007, 4:43 PM CT

STEREO panoramic images

The latest panoramic images from National Aeronautics and Space Administration's (NASA) twin STEREO (Solar Terrestrial Relations Observatory) spacecraft enable researchers to track solar storms from the sun to the Earth for the first time.

"The new view from the STEREO spacecraft will greatly improve our ability to forecast the arrival time of severe space weather," said Dr Russell Howard of the Naval Research Laboratory, Washington, the Principal Investigator of STEREO's Sun-Earth Connection Coronal and Heliospheric Investigation (SECCHI). "Prior imagery did not show the front of a solar disturbance as it travelled towards Earth, so we had to make estimates of when the storm would arrive. These estimates were uncertain by a day or so. With STEREO, we can track the front from the sun all the way to Earth, and forecast its arrival within a couple of hours".

The panoramic views are created by combining images from the SECCHI suite of instruments, including the Heliospheric Imager on both spacecraft - built in the UK by the University of Birmingham and CCLRC's Rutherford Appleton Laboratory.

Professor Keith Mason, Chief Executive of PPARC said, "Despite frequent observations over the last decade a number of questions remain unanswered about the nature of the Sun-Earth relationship and the way in which solar disturbances travel away from the sun. These new panoramic images illustrate the relationship from an entirely new perspective"......... Posted by: Sean      Read more         Source

February 28, 2007, 9:26 PM CT

Spacecraft Gets a Boost from Jupiter

NASA's New Horizons spacecraft successfully completed a flyby of Jupiter early this morning, using the massive planet's gravity to pick up speed on its 3-billion mile voyage to Pluto and the unexplored Kuiper Belt region beyond.

"We're on our way to Pluto," says New Horizons Mission Operations Manager Alice Bowman, of the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Md. "The swingby was a success; the spacecraft is on course and performed just as we expected."

New Horizons came within 1.4 million miles (2.3 million kilometers) of Jupiter at 12:43 a.m. EST, threading an "aim point" that puts it on target to reach the Pluto system in July 2015. During closest approach the spacecraft was out of touch with Earth - busily gathering science data on the giant planet, its moons and atmosphere - but by 11:55 a.m. EST mission operators at APL had established contact with New Horizons through NASA's Deep Space Network and confirmed its health and status.

The fastest spacecraft ever launched, New Horizons is gaining nearly 9,000 miles per hour (14,000 kilometers per hour) from Jupiter's gravity - half the speed of a space shuttle in orbit - accelerating past 52,000 mph (83,600 km/h) away from the Sun. New Horizons has covered approximately 500 million miles (800 million kilometers) since launch in January 2006, and reached Jupiter quicker than the seven prior spacecraft to visit the solar system's largest planet. Today it raced through an aim point just 500 miles (800 kilometers) across - the equivalent of a skeet shooter in Washington hitting a target in Baltimore on the first try......... Posted by: Sean      Read more         Source

February 20, 2007, 8:56 PM CT

Surprises from the Sun's South Pole

Eventhough very close to the minimum of its 11-year sunspot cycle, the Sun showed that it is still capable of producing a series of remarkably energetic outbursts - ESA-NASA Ulysses mission revealed.

In keeping with the first and second south polar passes (in 1994 and 2000), the latest high-latitude excursion of the joint ESA-NASA Ulysses mission has already produced some surprises. In mid-December 2006, eventhough very close to the minimum of its 11-year sunspot cycle, the Sun showed that it is still capable of producing a series of remarkably energetic outbursts.

The solar storms, which were confined to the equatorial regions, produced quite intense bursts of particle radiation that were clearly observed by near-Earth satellites. Surprisingly, similar increases in radiation were detected by the instruments on board Ulysses, even though it was three times as far away and almost over the south solar pole. "Particle events of this kind were seen during the second polar passes in 2000 and 2001, at solar maximum," said Richard Marsden, ESA's Ulysses Project Scientist and Mission Manager. "We certainly didn't expect to see them at high latitudes at solar minimum!".

Researchers are busy trying to understand how the charged particles made it all the way to the poles. "Charged particles have to follow magnetic field lines, and the magnetic field pattern of the Sun near solar minimum ought to make it much more difficult for the particles to move in latitude," said Marsden......... Posted by: Sean      Read more         Source

February 20, 2007, 8:40 PM CT

Ulysses scores a hat-trick

ESA-NASA Ulysses mission has marked another high point in its mission. For the third time in a long and highly successful career, Ulysses has reached its maximum south solar latitude of 80 degrees as it flies over the Sun's southern polar cap.

Launched in 1990, the European-built spacecraft visits both polar regions once every 6.2 years as it circles the Sun in an orbit that is almost perpendicular to the ecliptic, the plane in which the Earth and the planets move.

Eventhough originally designed for a mission lasting 5 years, the Ulysses space probe and its suite of 9 scientific experiments are still going strong after more than 16 years in orbit.

Operating the spacecraft has become more demanding over the years, however, as one consequence of the mission's longevity is a decrease in the electrical power available on board. "Ulysses uses a Radioisotope Thermoelectric Generator, or RTG for short, to generate the electricity needed for the spacecraft subsystems and science instruments", said Nigel Angold, ESA's Mission Operations Manager for Ulysses.

The RTG converts the heat produced by radioactive decay of its fuel into electrical power. "As a result of the decay process, the RTG output decreases with time", said Angold. In recent years, this has necessitated sharing the available power among the science instruments in such a way that key instruments are kept on permanently, while others are operated only part of the time......... Posted by: Sean      Read more         Source

January 30, 2007, 9:36 PM CT

Hubble's Main Camera Stops Working

On Saturday 27 January, Hubble's main camera, the Advanced Camera for Surveys (ACS), stopped working. Until a solution, at least in part, can be found, Hubble will be returned to work with the remaining instruments.

On Saturday 27 January 2007 at 13:34 CET the NASA/ESA Hubble Space Telescope entered into a protective "safemode" condition, most likely triggered by a short circuit in Hubble's main instrument the Advanced Camera for Surveys (ACS). ACS had been running since June 2006 on its secondary backup electrical system.

NASA has full responsibility for the mission operations of Hubble. Accordingly, NASA has set up an Anomaly Review Board. This will investigate whether ACS can be returned to using the primary electrical system enabling one of its parts, the Solar Blind Channel, to return to operation. However, at this time, it is expected that the main part of ACS will most likely not be restored.

Another Hubble Servicing Mission (SM4) has been scheduled for "not earlier than May 2008" by NASA. Options for repairing the ACS camera during this mission are being investigated.

In the meantime, Hubble will be returned to work again with the other available instruments onboard: the Near Infrared Camera and Multi-object Spectrometer (NICMOS), the Wide Field and Planetary Camera 2 (WFPC2) and the Fine Guidance Sensors (FGS'es).........

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January 15, 2007, 9:17 PM CT

First 3D map of the Universe's Dark Matter

By analysing the COSMOS survey - the largest ever survey undertaken with Hubble - an international team of researchers has assembled one of the most important results in cosmology: a three-dimensional map that offers a first look at the web-like large-scale distribution of dark matter in the Universe. This historic achievement accurately confirms standard theories of structure formation.

For astronomers, the challenge of mapping the Universe has been similar to mapping a city from night-time aerial snapshots showing only streetlights. These pick out a few interesting neighbourhoods, but most of the structure of the city remains obscured. Similarly, we see planets, stars and galaxies in the night sky; but these are constructed from ordinary matter, which accounts in total for only one sixth of the total mass in the Universe. The remainder is a mysterious component - dark matter - that neither emits nor reflects light.

An international team of astronomers led by Richard Massey of the California Institute of Technology (Caltech), USA, has made a three-dimensional map that offers a first look at the web-like large-scale distribution of dark matter in the Universe in unprecedented detail. This new map is equivalent to seeing a city, its suburbs and surrounding country roads in daylight for the first time. Major arteries and intersections are revealed and the variety of different neighbourhoods becomes evident.........

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January 9, 2007, 9:32 PM CT

Dust Around Nearby Star Like Powder Snow

Astronomers peering into the dust surrounding a nearby red dwarf star have observed that the dust grains have a fluffiness comparable to that of powder snow, the ne plus ultra of skiers and snowboarders.

This is the first definitive measurement of the porosity of dust outside our solar system, and is akin to looking back 4 billion years into the early days of our planetary system, say scientists at the University of California, Berkeley. That was the era after the formation of planets, but before the remaining snowball- or softball-sized rubble was ground into dust by collisions and blown out of the inner solar system.

"We think that this porosity is primordial, and reflects the agglomeration process whereby interstellar grains first assembled to form macroscopic objects," said James Graham, UC Berkeley professor of astronomy.

The grains are probably microscopic dirty snowballs, a mixture of ice and rock.

"The difference between a snowflake and a hailstone - both are ice but with very different porosities - occurs because they form very differently," he added. "Hailstones grow in violent thunderstorms; snowflakes grow under much more sedate meteorological conditions. Similarly, we conclude that the dust grains in the AU Mic debris disk formed by gentle agglomeration."........

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January 7, 2007, 8:47 AM CT

A New Class Of Supernova

Evidence for a significant new class of supernova has been found with the European Space Agency's XMM-Newton and NASA's Chandra X-ray Observatory. These results strengthen the case for a population of stars that evolve rapidly and are destroyed by thermonuclear explosions. Such 'prompt' supernovas could be valuable tools for probing the early history of the cosmos.

A team of astronomers uncovered a puzzling situation when they examined X-ray data from DEM L238 and DEM L249, the remnants of two supernovas in a nearby galaxy. On the one hand, the uncommonly high concentration of iron atoms implied that the remnants are the products of thermonuclear explosions of white dwarf stars, a well-known type of supernova known as 'Type Ia'. Conversely, the hot gas in the remnants was much denser and brighter in X-rays than typical Type Ia remnants.

(The large image shows a composite of Chandra X-ray data in blue and optical data in white of DEM L238 and DEM L249, two supernova remnants in the Large Magellanic Cloud. The inset reveals how DEM L238 (shown on the right in the wide-field view) appears in the three bands of X-ray emission, where low energy X-rays are shown in red, medium energies in green and high energies in blue. The central region of DEM L238 is green which indicates that it is rich in iron. This overabundance of iron identifies this object as a Type Ia supernova, possibly as a result from the explosion of a much younger star than expected. ........

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December 28, 2006, 9:59 PM CT

Finding a Different Mars Underneath

Mars is showing researchers its older, craggier face buried beneath the surface, thanks to a pioneering sounding radar co-sponsored by NASA aboard the European Space Agency's Mars Express orbiter.

Observations by the first project to explore a planet by sounding radar strongly suggest that ancient impact craters lie buried beneath the smooth, low plains of Mars' northern hemisphere. The technique uses echoes of waves that have penetrated below the surface.

"It's almost like having X-ray vision," said Dr. Thomas R. Watters of the National Air and Space Museum's Center for Earth and Planetary Studies, Washington. "Besides finding previously unknown impact basins, we've also confirmed that some of the subtle topographic depressions mapped previously in the lowlands are correlation to impact features."

Studies of how Mars evolved aid understanding of early Earth. Some signs of the forces at work a few billion years ago are more evident on Mars because, on Earth, a number of of them have been obliterated during Earth's more active resurfacing by tectonic activity.

Watters and nine co-authors report the findings in the Dec. 14, 2006 issue of the journal Nature.

The scientists used the orbiter's Mars Advanced Radar for Subsurface and Ionospheric Sounding, which was provided to the European Mars mission by NASA and the Italian Space Agency. The instrument transmits radio waves that pass through the Martian surface and bounce off features in the subsurface with electrical properties that contrast with those of materials that buried them.........

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