NIGHT DELIGHT | 'Supermoon' to grace Earth's skies

CAPE CANAVERAL, FLORIDA - The largest, brightest full moon in nearly seven decades will be on display in the coming days, promising Earth-bound sky-watchers a celestial "supermoon" spectacle.

The full moon will come nearer to Earth than at any time since 1948, astronomers said. At closest approach, which occurs at 6:23 a.m. EST on Monday, the moon will pass within 216,486 miles (348,400 km) of Earth's surface, about 22,000 miles (35,400 km) closer than average, they added.

The moon's distance from Earth varies because it is in an egg-shaped, not circular, orbit around the planet.

If skies are clear, the upcoming full moon will appear up to 14 percent bigger and 30 percent brighter than usual, making it what is called a supermoon, according to NASA.

A supermoon occurs when the timing of a full moon overlaps with the point in the moon's 28-day orbit that is closest to Earth.

About every 14th full moon is a supermoon, said University of Wisconsin astronomer Jim Lattis.

The next time a full moon comes as close to Earth will be in 2034.

"If you could stack up full moons next to each other, there is clearly a difference," Lattis said, but to a casual observer it is going to look very similar to a regular full moon.

Weather permitting, sky-watchers in North America and locations east of the International Dateline will have a better view on Sunday night since the moon will set less than three hours after closest approach on Monday.

"The difference in distance from one night to the next will be very subtle, so if it's cloudy on Sunday, go out on Monday. Any time after sunset should be fine," Noah Petro, deputy project scientist for NASA's Lunar Reconnaissance Orbiter, said in a statement.

source: interaksyon.com

Astronomers identify hundreds of new galaxies behind Milky Way

SYDNEY -- There's a mysterious force pulling the Milky Way galaxy towards it at 2 million kilometers per hour and scientists may have finally found out why.

An international team of researchers led by the International Center for Radio Astronomy Research at the University of Western Australia (UWA) have discovered 883 galaxies hidden in the nearby universe, 250 million light-years from earth, behind the Milky Way, a third of which had never been seen before.

"An average galaxy contains 100 billion stars, so finding hundreds of new galaxies hidden behind the Milky Way points to a lot of mass we didn't know about until now," University of Cape Town professor of Astronomy, Renee Kraan-Korteweg said in a statement on Wednesday.

The study's lead author, UWA professor of radio astronomy Lister Staveley-Smith said this discovery may help explain the "Great Attractor" region that is pulling the Milky Way and several other galaxies towards it with the gravitational force equivalent to a million, billion Suns.

"We don't actually understand what's causing this gravitational acceleration on the Milky Way or where it's coming from," Staveley-Smith said.

"We know that in this region there are a few very large collections of galaxies we call clusters or superclusters, and our whole Milky Way is moving towards them at more than two million kilometers per hour."

Astronomers have been trying to map the galaxies hidden in the so-called Zone of Avoidance, a part of the sky obscured by the Milky Way, since major deviations in the rate of expansion of the universe in this area were detected during the 1970s and 1980s.

By using Australia's chief scientific body CSIRO's Parks radio telescope, located in the middle of a sheep paddock in central New South Wales state and used in NASA's Apollo missions, the team were able to see through the stars and dust of the Milky Way into Zone of Avoidance.

"We've used a range of techniques but only radio observations have really succeeded in allowing us to see through the thickest foreground layer of dust and stars," Kraan-Korteweg said.

The Parks radio receiver, known in Australia as The Dish, has recently been fitted with innovative technologies, such as a 21-cm multi-beam receiver, that allow scientists to map the sky 13 times faster that they could before.

The study, published on Wednesday in the Astronomical Journal, involved researchers from Australia, South Africa, the United States and the Netherlands.

source: interaksyon.com

Mystery of Saturn's 'F ring' cracked, says study

PARIS - An enigmatic ring of icy particles circling Saturn, herded into a narrow ribbon by two tiny moons, was probably born of a cosmic collision, according to a study published Monday.

The so-called F ring, some 140,000 kilometers (87,000 miles) beyond the sixth planet from the Sun, orbits at the border between Saturn's other rings and several moons.

Further toward Saturn, millions of ice blocks populating the planet's haunting halos are prevented from cohering into moons by its powerful tidal forces.

Further out are Saturn's main moons, distant enough to have cohered into spheres with their own gravity: Mimas, Enceladus and Titan, which is the only moon in our Solar System with a substantial atmosphere.

And in the boundary zone F ring's icy particles whirl around the planet in a band barely 100 kilometers (60 miles) across, itself orbited by moons Prometheus and Pandora.     

Scientists have long known that these so-called shepherd moons were partly responsible for keeping the F ring in tight formation.

What they did not know was how this unusual configuration came into being.

Ryuki Hyodo and Keiji Ohtsuki, astronomers from Kobe University in Japan, used computer simulations to show that Prometheus and Pandora are likely the by-product of a collision at the outer edge of Saturn's ring system.

Previous speculation along these lines concluded that two icy mini-moons crashing head-on would have simply disintegrated, adding yet another ring to Saturn's collection.

But what if the objects were made of something less fragile, and hit each other at an angle?

In that case, "such an impact results in only partial disruption" of the mini-moons as opposed to their total destruction, the authors conclude.

The collision would also produce "the formation of a narrow ring of particles" which becomes a new ring.

Hyodo and Ohtsuki further speculate that this sort of process might not be a once-off oddity but rather the "natural outcome" of ring formation under certain conditions for giant gas planets.

This "may explain not only Saturn's F ring, but also features of the Uranian system," Aurelien Crida, a scientist at France's National Centre for Scientific Research wrote in a comment, also in Nature Geoscience.

Saturn is the second largest planet in our Solar System after Jupiter, and has a radius about nine times greater than Earth.

Its spectacular ring system has nine complete rings and several discontinuous arcs, all of them mainly made of ice particles, with lesser amounts of rocky debris and dust.

Some 60 moons circle Saturn, not including hundreds of "moonlets" such as the F ring's Prometheus and Pandora.

Much of the data and high-resolution images we have from Saturn and its rings was collected by the Cassini space probe, which arrived near the giant planet in 2004.

source: interaksyon.com

Chile hilltop razed for world's largest telescope

SANTIAGO -- Construction on the world's largest optical telescope began with a bang Thursday, as workers demolished a hilltop in Chile's Atacama desert.

The European Extremely Large Telescope, being built by the European Southern Observatory, aims to give astronomers new insight into the origins of the universe and help search for potentially habitable planets elsewhere in the galaxy.

Currently, "we have no proof of the existence of an Earth-like planet at the same distance from the sun in our galactic neighborhood," said astronomer Fernando Comeron, ESO's representative in Chile.

"That's not because they don't exist but because we didn't yet have the tools to detect them.

"With the E-ELT, we can."

Construction will take an estimated 10 years, and the telescope will be put into service two years later.

The first step, estimated at $1.4 billion, involves razing around 5,000 cubic meters (177,000 cubic feet) of rock off the top of Mount Armazones.

The newly flat surface will support the foundation of the telescope, with an "eye" -- a main mirror -- of 39 meters (128 feet) in diameter.

The new telescope's light-collecting surface "will be 10 to 15 times greater than those of existing telescopes," Comeron said.

Thanks to its dry and cold climate, and the lack of light pollution from cities in the remote region, Chile's Atacama desert provides an ideal location for astronomical research.

The ESO, a collaboration involving 15 mainly European countries, operates a number of high-powered telescopes in Chile, including the Very Large Telescope array and the Atacama Large Millimeter/Submillimeter Array, or ALMA.

source: interaksyon.com

Scientists find farthest galaxy so far

CAPE CANAVERAL, Florida -- Astronomers have found the most distant galaxy yet, a discovery that pushes back scientists' view of the universe to about 700 million years after it is thought to have come into existence.

Light from the galaxy, designated by scientists as z8_GND_5296, took about 13.1 billion years to reach the orbiting Hubble Space Telescope and the Keck Observatory in Hawaii, both of which detected the galaxy in infrared light.

"We are learning so much about a region so far back in time it's hard to comprehend. This galaxy we're seeing is almost 13.1 billion years ago and so this was something like 8 billion years before our sun was even born and of course much longer after that until life came around," said lead researcher Steven Finkelstein, an assistant professor with the University of Texas at Austin.

Surprisingly, out of a pool of 43 candidate distant galaxies, z8_GND_5296 was the only one that revealed the key chemical evidence needed to confirm its distance.

That left Finkelstein and colleagues wondering if they had uncovered a clue to a bigger mystery: How soon did light from the universe's first stars and galaxies pierce an obscuring veil of hydrogen gas that existed early in its history?

Scientists believe that at some point, high-energy ultraviolet radiation from exploded stars split the intergalactic hydrogen atoms into electrons and protons. Once ionized, the hydrogen would be electrically conductive and no longer scatter light.

That may have happened about the time of z8_GND_5296's existence.

The galaxy, which is about a billion times as massive as the sun, has two unusual characteristics, which may be a factor in why it is visible, while potential sister galaxies are not.

First, z8_GND_5296 is forming stars at a very fast pace, pumping out about 100 times more stars than the Milky Way galaxy, so it may be brighter than the other candidate galaxies.

Second, it contains a surprisingly high percentage of elements heavier than hydrogen and helium.

Those elements are forged by nuclear fusion inside stars, so either the galaxy contains the exploded remains of lots of massive stars or it formed in a region of space that had been previously seeded with the remnants of a prior generation of stars, scientists said.

"It could be that this one galaxy lives in an over-dense region of (ionized hydrogen) so we can see it ... but that's a little bit of conjecture. For all we know these other galaxies have just a lot more hydrogen gas within the galaxies themselves and that's why we can't see them," Finkelstein said.

He and colleagues hope to conduct a wider survey for ancient galaxies with Hubble, but more details about z8_GND_5296 will likely have to wait until NASA launches its successor observatory, the James Webb Space Telescope, targeted for launch in 2018.

The research appears this week in the journal Nature.

source: interaksyon.com