Posts Tagged ‘cosmology’

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360 Degree Panorama – Milky Way Arches Over Chile

12/10/2011

The Milky Way arches across this rare 360-degree panorama of the night sky above the Paranal observing platform in Chile, home of ESO’s Very Large Telescope.

The image was made from 37 individual frames with a total exposure time of about 30 minutes, taken in the early morning hours. The Moon is just rising and the zodiacal light shines above it, while the Milky Way stretches across the sky opposite the observatory.

Click For Enlarged Image - Its Gorgeous!

The open telescope domes of the world’s most advanced ground-based astronomical observatory are all visible in the image: the four smaller 1.8-metre Auxiliary Telescopes that can be used together in the interferometric mode, and the four giant 8.2-metre Unit Telescopes.

To the right in the image and below the arc of the Milky Way, two of ESO’s galactic neighbours, the Small and Large Magellanic Clouds, can be seen.

An interactive virtual tour is available here

Image Credit: ESO/H.H. Heyer

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NASA Selects Science Proposals For Concept Studies – Sun, Milky Way, Earth’s Atmosphere

29/09/2011

PASADENA, Calif. — NASA has selected 11 science proposals, including one from the Jet Propulsion Laboratory, for evaluation as potential future science missions. The proposals outline prospective missions to study the Earth’s atmosphere, the sun, the Milky Way galaxy, and Earth-like planets around nearby stars.

The selections were made from responses to Announcements of Opportunity for Explorer Missions and Explorer Missions of Opportunity released by the agency last November. The proposals were judged to have the best science value and feasible development plans.

“NASA continues to seek opportunities to push the cutting edge of science,” said Paul Hertz, chief scientist for NASA’s Science Mission Directorate, Washington. “Innovative proposals like these will help us better understand our solar system and the universe.”

Five Explorer Mission proposals were selected from 22 submitted in February. Each team will receive $1 million to conduct an 11-month mission concept study. Mission costs are capped at $200 million each, excluding the launch vehicle. In addition, one Explorer Mission proposal was selected for technology development and will receive $600,000. Five Mission of Opportunity proposals were selected from 20 submissions. Each will receive $250,000 to conduct an 11-month implementation concept study. Mission costs are capped at $55 million each.

Following the detailed mission concept studies, NASA plans to select up to two of the Explorer Mission proposals and one or more of the five Mission of Opportunity proposals in February 2013. The missions would then proceed toward flight and some could launch by 2016.

The selected Explorer Mission proposals are:

-Ionospheric Connection Explorer (ICON) Thomas Immel, Principal Investigator (PI), University of California, Berkeley — The mission would fly instruments to understand the extreme variability in our Earth’s ionosphere, which can interfere with communications and geopositioning signals.

-Fast INfrared Exoplanet Spectroscopy Survey Explorer (FINESSE) Mark Swain, PI, Jet Propulsion Laboratory, Pasadena, Calif. — This proposal would use a space telescope to survey more than 200 planets around other stars. This would be the first mission dedicated to finding out what comprises exoplanet atmospheres, what conditions or processes are responsible for their composition, and how our solar system fits into the larger family of planets.

-Observatory for Heteroscale Magnetosphere-Ionosphere Coupling (OHMIC) James Burch, PI, Southwest Research Institute, San Antonio — The mission would use a pair of spacecraft flying in formation to study the processes that provide energy to power space weather storms. These storms create auroras and other electromagnetic activity that can impact orbiting spacecraft operations.

-Transiting Exoplanet Survey Satellite (TESS) George Ricker, PI, Massachusetts Institute of Technology, Cambridge, Mass. — Using an array of telescopes, TESS would perform an all-sky survey to discover transiting exoplanets, ranging from Earth-sized to gas giants, in orbit around the nearest and brightest stars in the sky. The mission’s primary goal would be to identify terrestrial planets in the habitable zones of nearby stars.

-Atmosphere-Space Transition Region Explorer (ASTRE) Robert Pfaff Jr., PI, NASA’s Goddard Space Flight Center, Greenbelt, Md. — The mission would study the interaction between the Earth’s atmosphere and the ionized gases of space. By flying excursions deep into the Earth’s upper atmosphere, its measurements would improve satellite drag models and show how space-induced currents in electric power grids originate and evolve with time.

The selected Explorer Mission of Opportunity proposals are:

-Global-scale Observations of the Limb and Disk (GOLD) Richard Eastes, PI, University of Central Florida, Orlando — This would involve an imaging instrument that would fly on a commercial communications satellite in geostationary orbit to image the Earth’s thermosphere and ionosphere.

-Neutron star Interior Composition ExploreR (NICER) Keith Gendreau, PI, Goddard — This mission would place an X ray timing instrument on the International Space Station (ISS) to explore the exotic states of matter within neutron stars and reveal their interior and surface compositions.

-Coronal Physics Investigator (CPI) John Kohl, PI, Smithsonian Astrophysical Observatory, Cambridge — A solar telescope would be mounted on the ISS to investigate the processes that produce the sun’s fast and slow solar wind.

-Gal/Xgal U/LDB Spectroscopic/Stratospheric THz Observatory (GUSSTO) Christopher Walker, PI, University of Arizona, Tucson — This mission would launch a high altitude balloon with a one-meter telescope to provide a comprehensive understanding of the inner workings of our Milky Way galaxy and one of our galaxy’s companion galaxies, the Large Magellanic Cloud.

-Ion Mass Spectrum Analyzer for SCOPE (IMSA), Lynn Kistler PI, University of New Hampshire, Durham — This partner mission of opportunity would provide a composition instrument to the Japanese cross-Scale Coupling in the Plasma universE (SCOPE) mission. SCOPE will study fundamental space plasma processes including particle acceleration, magnetic reconnection, and plasma turbulence.

The proposal selected for technology development funding is:

-The Exoplanetary Circumstellar Environments and Disk Explorer (EXCEDE), Glenn Schneider, PI, University of Arizona, Tucson – The technology development effort will enable studies of the formation, evolution, and architectures of exoplanetary systems through direct imaging.

The Explorer program is the oldest continuous program at NASA. It is designed to provide frequent, low-cost access to space using PI-led space science investigations relevant to the agency’s astrophysics and heliophysics programs. Initiated with the Explorer 1 launch in 1958 that discovered the Earth’s radiation belts and including the Cosmic Background Explorer mission that led to Nobel prizes for their investigators, the Explorer program has launched more than 90 missions. It is managed by Goddard for NASA’s Science Mission Directorate in Washington.

For more information about the Explorer program, visit: http://explorers.gsfc.nasa.gov .

NASA’s Jet Propulsion Laboratory is a division of the California Institute of Technology in Pasadena.

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Image of the Week: Rare Martian Lake Delta Spotted by Mars Express

28/09/2011

09.28.11 – via UKSpaceAgency: Europe’s Mars Express has spotted a rare case of a crater once filled by a lake, revealed by the presence of a delta. The delta is an ancient fan-shaped deposit of dark sediments, laid down in water. It is a reminder of Mars’ past, wetter climate.

Holden crater (left) and Eberswalde crater (right). Credits: ESA/DLR/FU Berlin (G. Neukum).
Holden crater (left) and Eberswalde crater (right).
Credits: ESA/DLR/FU Berlin (G. Neukum).

The delta is in the Eberswalde crater, in the southern highlands of Mars. The 65 km-diameter crater is visible as a semi-circle on the right of the image and was formed more than 3.7 billion years ago when an asteroid hit the planet. The rim of the crater is intact only on its right-hand side. The rest appears only faintly or is not visible at all. A later impact created the 140 km diameter Holden crater that dominates the centre and left side of the image. The expulsion of large amounts of material from that impact buried parts of Eberswalde.

However, within the visible part of Eberswalde, the delta and its feeder channels are well preserved, as seen near the top right of the crater. The delta covers an area of 115 square kilometres. Small, meandering feeder channels are visible towards the top of the crater, which would have filled it to form a lake.

Eberswalde crater in perspective. Credits: ESA/DLR/FU Berlin (G. Neukum).
Eberswalde crater in perspective.
Credits: ESA/DLR/FU Berlin (G. Neukum).

After the deposition of the delta sediments in the crater’s ancient lake, fresher sediments accumulated to cover up a major part of both the channels and the delta. These secondary sediments, presumably deposited by the wind, were later eroded in the delta area, exposing an inverted relief of the delta structure.

This delta structure, first identified with NASA’s Mars Global Surveyor spacecraft, is characteristic of the presence of a lake in the crater at that time. Such features provide a clear indication that liquid water flowed across the surface of Mars in the planet’s early history.

UK involvement in Mars Express is funded by the UK Space Agency. More information can be found in the missions section of the website.

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Was a Giant Planet Ejected from the Solar System?

27/09/2011

Gas-giant-kick

The Fifth Planet sounds like a great name for a sci-fi movie — perhaps a sequel to the 1997 movie “The Fifth Element.” But the fifth planet may be real; a hypothesized giant world that was flung out of our solar system four billion years ago. It would have drifted tens of thousands of light years away by now.

Why even suspect that such a planet existed?

SLIDE SHOW: Top Exoplanets for Alien Life

Though astronomers have found many planetary systems around neighboring stars, our own solar system looks like it’s the exception rather than the rule. We’re discovering that our system is an uncommonly orderly place where the planets behave themselves in wide orbits that are nearly circular.

But the planetary systems around other stars found so far present sort of a Wild West of planets. Their orbits can be steeply inclined to one another (our eight major planets are coplanar). There are many giant planets that have migrated precariously close to their stars. Other planets are in roller-coaster highly elliptical orbits that alternatively freeze and cook them.

Even more befuddling, it’s hard for theoreticians to build a planet formation model that winds up looking like our solar system.

ANALYSIS: Weird Exoplanet Orbits Could Prevent Alien Life

Protoplanetary

ANALYSIS: Does a Massive Planet Lurk in the Outer Solar System?

A new set of computer simulations by David Nesvorny of the Southwest Research Institute in Boulder, Colorado, shows that this will work if there was once a fifth giant planet in addition to Jupiter, Saturn, Uranus, and Neptune.

Nesvorny models place a fifth hefty planet, several dozen times the mass of the Earth at various possible locations in the outer solar system: midway between Saturn and Uranus, and just beyond Neptune. In this game of orbital musical chairs, the fifth planet was ejected after a tussle with Jupiter –- sort of a celestial King Kong vs. Godzilla.

This may sound extraordinary but there is plenty of evidence for orphaned free-floating planets wandering our galaxy. A 2006-2007 survey of the Milky Way used gravitational lensing to find 10 dark objects drifting in front of distant background stars. Statistically, this means there could be as many as hundreds of billions of castoff planets plying inside our galaxy.

ANALYSIS: No ‘Nemesis’ Boosting Comet Impacts

Looking for evidence of a fifth giant planet calls for solar system forensics. God didn’t leave behind any file footage of the solar system’s formative years, after all.

First, it is known that Uranus and Neptune are too far from the sun for them to have formed in their present locations. There simply has not been enough time and materials for them to agglomerated into 15-Earth mass worlds. Uranus and Neptune must have formed closer into the sun and then migrated outward.

This implies that the early solar system was very chaotic. Smaller bodies, the planetesimals, were gravitationally kicked around and the exchange of momentum widened the orbits of the outer planets. Our moon bears the scars of this rough and tumble period called the Late Heavy Bombardment, of about 4 billion years ago.

The planetesimal debris was then snowplowed outward to form the Kupier belt, where Pluto dwells. Kuiper belt objects are not spread out uniformly in but are clustered into three distinct populations. This means that the belt was; extensively sculpted by the gravitational influence of the giant planets.

ANALYSIS: Uranus Pathfinder: Mission to the Mysterious Ice Giant

The ejected planet would not necessarily be lifeless even though it is sailing through the numbing cold of interstellar space. It presumably would have moons. Gravitational tidal forces could heat them so that they would remain warm in the absence of a star. The moons Io (orbiting Jupiter) or Enceladus (orbiting Saturn) are the archetype of what would be plausible. Microbes could live happily without the need for a sun in the sky. Among the billions of flung off worlds in our galaxy, this one would be isotopically stamped: Made By Sol.

source: Discovery illustrations: NASA

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Autumnal Equinox 2011 – Stars & Planets Lining Up For Change of Seasons

23/09/2011

Jupiter, Big Dipper add to Northern Hemisphere’s cosmic display

09/23/11 – via National Geographic – Stars and planets are lining up for the change of seasons during the Northern Hemisphere’s autumnal equinox – the first day of fall – which will happen in 2011 at 5:05 a.m. ET Friday.

Indigenous women participate in a Maya ceremony on Sunday marking the autumnal equinox.

As if to mark the first full night of fall, the bright star Arcturus will hang high above the point where the sun sets on September 23, said Alan MacRobert, senior editor of Sky & Telescope magazine in Cambridge, Massachusetts.

Off to Arcturus’ right will be the Big Dipper, positioned so that its ladle-like shape appears upright to ground-based observers, with its bowl to the right and handle to the left.

Meanwhile, planet-hunters will be able to watch brilliant Jupiter glide across the sky almost all night long from the fall equinox through the end of October.

By mid-evening on the night of the fall equinox, the Pleiades star cluster will seem to follow Jupiter in its path across the sky.

During the start of fall 2011, “Jupiter is by far and away the brightest point-like object in the sky, but later in the season it is going to get competition from Venus,” MacRobert added.

“By Thanksgiving, if you look low in the southwest after sunset as twilight comes on, Venus will be shining there, brighter than Jupiter.”

Venus will continue to rise higher in the sky and, come January, the planet will begin a “very high, bright, dramatic showing all through this coming winter and into April and May,” he said.

Equinoxes as Season Starters

The march of the seasons – winter, spring, summer, and fall – stems from the “clearly definable” position of the sun on the summer and winter solstices, according to Judith Young, a professor of astronomy at the University of Massachusetts in Amherst.

“The solstices are very accurately measured as the northernmost point that the sun rises along the horizon in June and the southernmost point along the horizon in December,” she said. “It doesn’t matter where you are on Earth – that’s true.”

This regularity allowed for the construction of Stonehenge in England some 5,000 years ago, where sunrise on the summer solstice is still celebrated with fervor.

In modern times, the solstice points became the astronomical definitions of when the summer and winter seasons begin. In the Northern Hemisphere, June features the summer solstice, while in the Southern Hemisphere, June marks the first day of winter.

Since the equinoxes fall roughly halfway between the solstices, they got pegged as the starts of the other two seasons, fall and spring, Young said.

However, the autumnal equinox and vernal – or spring – equinox aren’t exactly midway between the solstices “because the Earth’s orbit is not a true circle. We have a slightly elliptical orbit,” Young explained.

This elongated orbit means that Earth goes faster around the sun in January, when it’s closest to the star, than it does when it’s farthest away from the sun in July.

“We arrive at the September equinox a day late, because we were going a little bit slower in July, and we arrive at the March equinox a day earlier,” Young said.

But our late arrival doesn’t make the first day of fall any less special.

For instance, the spring and fall equinoxes are the only two times during the year when the sun rises due east and sets due west, according to Sky & Telescope’s MacRobert.

 

The autumnal equinox and vernal equinox are also the only days of the year when a person standing on the Equator can see the sun passing directly overhead.

On the Northern Hemisphere’s autumnal equinox, a person at the North Pole would see the sun skimming across the horizon, signaling the start of six months of darkness.

On the same day, a person at the South Pole would also see the sun skim the horizon, beginning six months of uninterrupted daylight.

(See pictures of the sun’s path across the sky – an entire year in a single frame.)

The Lag of the Seasons

The defined start of the seasons based on the sun’s positions may seem counterintuitive. After all, in the summer, daylight begins to grow shorter just as the season officially begins.

Shouldn’t the June solstice instead be called midsummer, as was celebrated in Shakespearean times?

From a climatological perspective, the answer is no, according to Young, who explained that “there’s something called the lag of the seasons where [for example] the temperatures continue to warm up after you’ve had the northernmost sunrise in the Northern Hemisphere” on the summer solstice.

This lag means that, in the Northern Hemisphere, the warmest days of summer don’t actually arrive until late July and early August, and the coldest days of the winter are in January and February.

“Because of that lag, it actually made climatological sense to define the seasons as starting when we do,” Young said.

Autumnal Equinox Illusions

But don’t be fooled by the notion that on the autumnal equinox the length of day is exactly equal to the length of night.

The true days of day-night equality always fall after the autumnal equinox and before the vernal equinox, according to Geoff Chester, a public affairs specialist with the U.S. Naval Observatory in Washington, D.C.

The difference is a matter of geometry, atmosphere, and language.

Day and night would each be exactly 12 hours long on a spring or fall equinox only if the sun was a single point of light and Earth had no atmosphere.

But the sun, as seen from Earth, is nearly as large as a little fingertip held at arm’s length – a size known to astronomers as half a degree wide.

Sunrise is defined as the moment the top edge of the sun appears to peek over the horizon. Sunset is when the very last bit of the sun appears to dip below the horizon.

The vernal and autumnal equinoxes, meanwhile, occur when the center of the sun’s disk crosses what’s known as the celestial equator, an imaginary line that projects outward from Earth’s Equator, Chester noted.

What’s more, Earth’s atmosphere bends sunlight when it’s close to the horizon, making the sun appear to rise a few minutes earlier than it actually does.

“Those factors all combine to make the day of the equinox not the day when we have 12 hours [each] of light and darkness,” Chester said.

Most people will never see the full 12 hours of sunup and sundown on the autumnal equinox, the University of Massachusetts’ Young added.

That’s because most people have hills or trees blocking their views of a flat horizon. Thus, they see the sun rise later and set earlier than it does for a horizon without obstruction, she said.

What’s more, for people who don’t live on the Equator, the sun still rises and sets at an angle to the horizon, noted Young, who built a Stonehenge-like solar calendar and observatory on the University of Massachusetts campus.

Even though the sun rises due east and sets due west on the autumnal equinox, “you’ll only see an east sun rising and west sun setting with an obstruction-free horizon,” she said.

Equinox Oddity

Another equinox oddity: A rule of the calendar keeps spring almost always arriving on March 20 or 21 – but sometimes on the 19th – Sky & Telescope’s MacRobert said.

In 1582 Pope Gregory XIII established the Gregorian calendar, which most of the world now observes, to account for an equinox inconvenience.

If the pope hadn’t established the new calendar, every 128 years the spring equinox would have come a full calendar day earlier, eventually putting Easter in chilly midwinter.

“It begins with the fact that there is not an exact number of days in a year,” MacRobert said.

Before the pope’s intervention, the Romans and much of the European world marked time on the Julian calendar.

Instituted by Julius Caesar, the old calendar counted exactly 365.25 days a year, averaged over a four-year cycle. Every four years a leap day helped keep things on track.

It turns out, however, that there are 365.24219 days in an astronomical “tropical” year – defined as the time it takes the sun, as seen from Earth, to make one complete circuit of the sky.

Using the Julian calendar, the seasons were arriving 11 minutes earlier each year. By 1500 the spring equinox had fallen back to March 11.

To fix the problem, the pope decreed that most century years (such as 1700, 1800, and 1900) would not be leap years. But century years divisible by 400, like 2000, would be leap years.

Under the Gregorian calendar, the year is 365.2425 days long, “close enough to the true fraction that the seasons don’t drift,” MacRobert said.

With an average duration of 365.2425 days, Gregorian years are now only 27 seconds longer than the length of the tropical year – an error which will allow for the gain of one day over a period of about 3,200 years.

Nowadays, according to the U.S. Naval Observatory’s Chester, equinoxes migrate through a period that occurs about six hours later from calendar year to calendar year, due to the leap-year cycle.

The system resets every leap year, slipping a little bit backward until a non-leap century year nudges the equinoxes forward in time once again.

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New Video Reveals Giant Asteroid Vesta as Seen by Spacecraft

21/09/2011

Mon, 19 Sep 2011 00:00 CDT via Space.com – A new video from a NASA spacecraft takes viewers on a flyover journey of Vesta, the second-largest object in the main asteroid belt between Mars and Jupiter.

Scientists constructed the two-minute video from images taken by NASA’s Dawn probe, which has been orbiting Vesta since July.

In addition to giving armchair astronomers around the world a great look at Vesta, the video should help scientists better understand the forces that shaped the massive space rock, researchers said.

In the video, the 330-mile (530-kilometer) Vesta is not entirely lit up; its northern latitudes are shrouded in darkness. That’s because the giant asteroid Vesta has seasons just like Earth, researchers said.It is currently winter in the Vestan north, and the north pole is in perpetual darkness.

A huge southern crater

The video highlights a huge circular depression several hundred miles wide near Vesta’s south pole. NASA’s Hubble Space Telescope first spotted this feature years ago, and scientists have been eager to get a better look at it ever since.

The cliffs of this massive depression rise several miles up from its floor, and a 9-mile (15-km) high mountain rises from the structure’s base, researchers said.

Researchers have used Dawn‘s images to determine Vesta’s rotational axis and to map out a system of latitude and longitude. The team defined the asteroid’s zero-longitude line, or prime meridian, using a small crater they named “Claudia,” after a Roman woman who lived in the second century B.C.

Vesta took its name from the Roman goddess of the hearth, home and family. Craters on the space rock will be named after the vestal virgins – priestesses of the goddess – and famous Roman women, researchers said. Other features will take the names of towns and festivals of ancient Rome.

Sharper images coming soon

Dawn captured the new images used in the video while it was still about 1,700 miles (2,700 km) above Vesta’s surface. The spacecraft is slated to move down to a lower orbit in October, from which it should be able to snap even closer photos, with a resolution about eight times higher, researchers said.

The $466 million Dawn spacecraft launched in September 2007 and entered orbit around Vesta on July 15 of this year. Next July, it will head off to study Ceres, the largest object in the asteroid belt. At 590 miles (950 km) across, Ceres is so large that astronomers consider it a dwarf planet. [Meet the Solar System’s Dwarf Planets]

Dawn is expected to reach Ceres in February 2015. The probe’s observations should allow scientists to compare the dwarf planet to Vesta. Unlike the drier and more evolved Vesta, Ceres is considered to be more primitive and wet, possibly harboring water ice, researchers have said.

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Zooming in on Earth – Amazing Time-Lapse Video From International Space Station

19/09/2011

Wouldn’t anyone want the chance to see it for themselves with their own eyes?

Well I guess its possible if you have at least a cool million dollars to spend on the new Soviet Space Hotel.

That or perhaps alien abduction.

But what do I know?

Take me to your leader.  I’m tired of ours.

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