RSSArchive for January, 2013

461 new planet candidates

Artist's impression of a planetary system

The number of exoplanet candidates found by the Kepler space observatory, has jumped up by 461. Image: ESO/M. Kornmesser

  • NASA’s Kepler space mission aims to detect Earth-like planets
  • 2,740 planet candidates detected orbiting 2,036 stars
  • Kepler now has 105 confirmed planets

SCIENTISTS WITH NASA’S KEPLER MISSION have announced the discovery of 461 new planet candidates. Four of the potential new planets are less than twice the size of Earth and orbit in their star’s ‘habitable zone, the region in the planetary system where liquid water might exist on the surface of a planet.

Based on observations conducted from May 2009 to March 2011, the findings show a steady increase in the number of smaller-size planet candidates and the number of stars with more than one candidate.

“There is no better way to kickoff the start of the Kepler extended mission than to discover more possible outposts on the frontier of potentially life bearing worlds,” said Christopher Burke, Kepler scientist at the SETI Institute in Mountain View, California, who is leading the analysis.

Flat-pack planetary systems

Since the last Kepler catalogue was released in February 2012, the number of candidates discovered in the Kepler data has increased by 20 percent and now totals 2,740 potential planets orbiting 2,036 stars.

The most dramatic increases are seen in the number of Earth-size and super Earth-size candidates discovered, which grew by 43 and 21 percent respectively.

Plot of exoplanets discovered in Kepler data

Since the last Kepler catalogue was released in February 2012, the number of candidates discovered in the Kepler data has increased by 20 percent and now totals 2,740 potential planets orbiting 2,036 stars. NASA

The new data increases the number of stars discovered to have more than one planet candidate from 365 to 467. Today, 43 percent of Kepler’s planet candidates are observed to have neighbour planets.

“The large number of multi-candidate systems being found by Kepler implies that a substantial fraction of exoplanets reside in flat multi-planet systems,” said Jack Lissauer, planetary scientist at NASA’s Ames Research Center in Moffett Field, California. “This is consistent with what we know about our own planetary neighborhood.”

New Earths – just a question of when

The Kepler space telescope identifies planet candidates by repeatedly measuring the change in brightness of more than 150,000 stars in search of planets that pass in front, or ‘transit,’ their host star. At least three transits are required to verify a signal as a potential planet.

Scientists analysed more than 13,000 transit-like signals to eliminate known spacecraft instrumentation and astrophysical false positives – phenomena that masquerade as planetary candidates – to identify the potential new planets.

Candidates require additional follow-up observations and analyses to be confirmed as planets. At the beginning of 2012, 33 candidates in the Kepler data had been confirmed as planets. Today, there are 105.

“The analysis of increasingly longer time periods of Kepler data uncovers smaller planets in longer period orbits – orbital periods similar to Earth’s,” said Steve Howell, Kepler mission project scientist at Ames. “It is no longer a question of will we find a true Earth analogue, but a question of when.”

The complete list of Kepler planet candidates is available in an interactive table at the NASA Exoplanet Archive. The archive is funded by NASA’s Exoplanet Exploration Program to collect and make public data to support the search for and characterisation of exoplanets and their host stars.

More information:

NASA Exoplanet Archive

Kepler Mission

Adapted from information issued by NASA.

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Where is all the antimatter?

The interior of the Daya Bay neutrino experiment

Interior of the Daya Bay neutrino experiment. The ‘bumps’ lining the wall are sensitive detectors that pick up the flash of light when an anti-neutrino is found.

A PRECISE MEASUREMENT of elusive, nearly massless particles, has provided a crucial hint as to why the universe is dominated by matter, and not by its close relative, anti-matter.

The particles, called anti-neutrinos, were detected at the underground Daya Bay experiment, located near a nuclear reactor in China, 55 kilometres north of Hong Kong.

For the measurement, made in 2012, the Daya Bay collaboration has been named runner-up for breakthrough of the year from Science magazine.

Anti-particles are almost identical twins of sub-atomic particles (electrons, protons and neutrons) that make up our world. When an electron encounters an anti-electron, for example, both are annihilated in a burst of energy. Failure to see these bursts in the universe tells physicists that anti-matter is vanishingly rare, and that matter rules the roost in today’s universe.

Neutrino – the last hope?

“At the beginning of time, in the Big Bang, a soup of particles and anti-particles was created, but somehow an imbalance came about,” says Karsten Heeger, a professor of physics at the University of Wisconsin-Madison (UW-Madison). “All the studies that have been done have not found enough difference between particles and anti-particles to explain the dominance of matter over anti-matter.”

But the neutrino, an extremely abundant but almost massless particle, may have the right properties, and may even be its own anti-particle, Heeger says. “And that’s why physicists have put their last hope on the neutrino to explain the absence of anti-matter in the universe.”

Daya Bay pool holding four anti-neutrino detectors

A pool holding four anti-neutrino detectors begins filling with ultra-pure water in September, 2012 at the Daya Bay Neutrino experiment. The experiment is helping to explain why the universe contains virtually no anti-matter.

A fertile source

Reactors, Heeger says, are a fertile source of anti-neutrinos, and measuring how neutrinos change during their short flights from the reactor to the detector, gives a basis for calculating a quantity called the “mixing angle,” the probability of transformation from one flavour into another.

The measurement of the Daya Bay experiment, released in March 2012, even before the last set of detectors was installed, showed a surprisingly large angle, Heeger says. “People thought the angle might be really tiny, so we built an experiment that was 10 times as sensitive as we ended up needing.

As expected, Science‘s breakthrough of the year was the detection of the Higgs boson, an elusive sub-atomic particle that completes the “particle zoo” predicted by the standard model of physics.

Adapted from information issued by University of Wisconsin-Madison. Daya Bay photo courtesy Roy Kaltschmidt, LBNL. Detector image by Roy Kaltschmidt, Berkeley Lab Public Affairs).

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Surveyor 7: Setting the scene for Apollo

PRIOR TO THE SUCCESSFUL Apollo lunar landings, NASA sent a series of uncrewed probes to the Moon to learn more about the lunar surface. The last of these, Surveyor 7, was launched 45 years ago today.

A model of the Surveyor 7 spacecraft

A model of the Surveyor 7 spacecraft

Surveyor 7 was the last of the original series of Surveyor moon landers of the late 1960s and was dedicated primarily to scientific investigations. By 1968, the spacecraft’s predecessors had already performed much of the investigative work into the feasibility of a future human mission to the moon.

Surveyor 7’s mission was decidedly unique – it was the only spacecraft of the series to land in the lunar highland region. And it had the most extensive set of instruments, with which it conducted a number of scientific experiments on the lunar soil. Findings from Surveyor 7 were fairly consistent with earlier missions except that chemical analysis of the highland crust showed it to have less iron than samples from the lunar maria.

More information: Surveyor 7

Adapted from information issued by NASA.

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Andromeda, we have you surrounded

The Andromeda galaxy

The Andromeda galaxy appears to be surrounded by a circle of dwarf galaxies (not visible in this image). Credit: ESA / Hubble & Digitized Sky Survey 2 / Davide De Martin (ESA/Hubble).

JUST AS BILBO BAGGINS found himself the centre of some unwanted attention from a bunch of dwarfs, the Andromeda galaxy appears to have a bunch of smaller, dwarf galaxies circling it in a single plane, according to new research. The finding, published in the prestigious journal Nature, presents a challenge to ideas of how all galaxies form and evolve.

The surprising research result reveals that around half of Andromeda’s 30-odd known dwarf galaxy satellites are orbiting the larger Andromeda Galaxy – the closest giant cosmic neighbour to our own galaxy, the Milky Way.

The international group of astronomers who discovered the cosmic curiosity include Professor Geraint Lewis from the University of Sydney’s School of Physics, and Anthony Conn, a PhD student at Macquarie University, and Dr Dougal Mackey from the Australian National University.

“Astronomers have been observing Andromeda since Persian astronomers first noted it over a thousand years ago, but it is only in the past decade that we have truly studied it in exquisite detail with the Pan-Andromeda Archaeological Survey,” said Lewis, one of the lead authors on the Nature paper.

Completely unexpected findings

“The Pan-Andromeda Archaeological Survey – cutely called PAndAS – is a large project that ran between 2008 and 2011, using the Canada-France-Hawaii Telescope situated on the Mauna Kea volcano on the Big Island of Hawaii,” explained Lewis. “Now that we’re examining the data it collected, it is providing our first panoramic view of our closest large companion in the cosmos.”

“When we looked at the dwarf galaxies surrounding Andromeda, we expected to find them buzzing around randomly, like angry bees around a hive.

Diagram showing the position of dwarf galaxies orbiting Andromeda

Left: A close up of the Andromeda galaxy. Right: Diagram showing the position of the dwarf galaxies (red dots) detected orbiting Andromeda in a single plane, in the direction of the red arrow. Credit: R. Ibata (PAndAS team).

“Instead, we’ve found that half of Andromeda’s satellites are orbiting together in an immense plane, which is more than a million light years in diameter but only 30,000 light years thick. These dwarf galaxies have formed a ring around Andromeda.”

“This was completely unexpected – the chance of this happening randomly is next to nothing. It really is just weird,” said Professor Lewis.

Not anticipated by computer modelling

Large galaxies, like Andromeda and our own Milky Way, have long been known to be orbited by an entourage of smaller galaxies. These small galaxies, which are individually anywhere from ten to at least hundreds of thousands of times fainter than their bright hosts, were thought to trace independent paths around those galaxies.

For several decades, astronomers have used computer models to predict how dwarf galaxies should orbit large galaxies, and every time they found that dwarfs should be scattered randomly over the sky. Never, in these synthetic universes, did they see dwarfs arranged in a plane like that observed around Andromeda.

“Now that we’ve found that the majority of these dwarf galaxies orbit in a [plane] around the giant galaxy Andromeda, it looks like there must be something about how these galaxies formed or subsequently evolved that has led them to trace out this peculiar coherent structure,” said Professor Lewis.

“Dwarf galaxies are the most numerous galaxy type in the universe, so understanding why and how they form this disc around the giant galaxy is expected to shed new light on the formation of galaxies of all masses.”

PhD student, Anthony Conn, whose research proved key to this study said, “It is very exciting for my work to reveal such a strange structure. It has left us scratching our heads as to what it means.”

There have been similar claims of an extensive plane of dwarf galaxies about our own Milky Way Galaxy, with some claiming that the existence of such strange structures points to a failing in our understanding of the fundamental nature of the Universe.

Adapted from information issued by the University of Sydney.

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Why was Australia lit up like Christmas tree?

Composite image of Australia at night

The apparent abundance of lights in this satellite image of Australia’s desolate outback, is easily explained – the image is made up of multiple images taken over many days and combined one on top of the other. So occasional fires or lightning bursts here and there have apparently joined up to produce large light shows in remote areas.

TWO WEEKS AGO, NASA’S Earth Observatory web site published a new map of the Earth at night, built by Earth Observatory designers together with colleagues at the US National Geophysical Data Center. That map—made possible by a new NASA and the National Oceanic and Atmospheric Administration (NOAA) satellite—showed the footprint of human civilisation on the planet, as revealed by the lights we use to brighten the darkness.

But it turns out the map showed something more. Astute readers noticed lights in areas that were thought to be uninhabited. Many of those readers pointed to Western Australia and asked: How can there be so much light there?

The image above shows the night-lights of Australia as observed by the Visible Infrared Imaging Radiometer Suite (VIIRS) on the Suomi NPP satellite in April and October 2012. It is made up of multiple images that show both manmade light sources and the light of fires. The images were acquired over nine days in April 2012 and thirteen days in October 2012.

A closer view of Western Australia at night.

A closer view of Western Australia at night.

The extent of the lighting is a results of combining multiple images. Fires and other lights that were detected on one day were integrated into the composite, multi-day picture despite being temporary phenomena. Because different lands burned at different times that the satellite passed over, the cumulative result is the appearance of a massive blaze. But while the cities are fixed, the fires were temporary, moveable features.

Not every light in the night view matches up with a fire—partly because the fire map does not include fires from April and partly because not every fire leaves a scar that is detectable from space. Even simple cloud cover could prevent burn scars from being observed.

Aside from the fires, some of the night lights appearing in uninhabited areas can be attributed to natural gas flares, lightning, oil drilling or mining operations, and fishing boats—all of which can show up as points of light.

Adapted from information issued by NASA Earth Observatory. NASA Earth Observatory images by Robert Simmon, using Suomi NPP VIIRS data provided by Chris Elvidge (NOAA National Geophysical Data Center); MODIS Active Fire & Burned Area Products; and urban data from the University of Wisconsin-Madison Center for Sustainability and the Global Environment. Suomi NPP is the result of a partnership between NASA, NOAA, and the Department of Defense. Caption by Michael Carlowicz.

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What’s up? Night sky for January 2013

Except where indicated, all of the phenomena described here can be seen with the unaided eye. And unless otherwise specified, dates and times are for the Australian Eastern Daylight Time (AEDT) zone, and sky directions are from the point of view of an observer in the Southern Hemisphere.

January 2

If you’re an early riser, take a look out to the north-west and high up you’ll see a bright star near the Moon. This is Regulus, the brightest star in the constellation Leo. Actually, Regulus is not one star but four, grouped into two pairs. Multiple star systems are very common throughout the Milky Way galaxy.

The Moon will appear near the bright star Regulus on January 2.

The Moon will appear near the bright star Regulus on January 2.

And today the Earth reaches perihelion in its orbit around the Sun. Perihelion is the point in a solar orbit when the body in question (eg. Earth) is at its closest to the Sun. Perihelion occurs today at midday AEDT, at a distance between Earth and Sun of about 147,098,089 kilometres. (The opposite of perihelion is aphelion, which for Earth will occur on July 5, 2012 at a distance of about 152,097,351 kilometres.)

January 5

It is Last Quarter Moon today at 2:58pm Sydney time (03:58 Universal Time).

January 6

If you’re up very early this morning (from 2:00am onwards), you’ll see a bright star appearing to almost touch the Moon. This Spica, the brightest star in the constellation Virgo; it is a blue giant star about 260 light-years from Earth. And don’t miss tomorrow’s morning sight…

January 7

This morning, the Moon has moved along a bit in its orbit, and no longer appears to be near Spica. Instead, it appears to hover just above what appears to be another bright star, but which is instead the planet Saturn. If you have a small telescope, or can borrow someone else’s, take a look at Saturn – you’ll see the huge rings tilted nicely to our line of sight, and – depending on the power of your telescope – you might also be able to make out a couple of the planet’s moons, although they’ll only look like bright pinpricks of light.

January 7: If you're an early riser, take a look at the Moon and you'll see what appears to be bright star just below it. Well, that's actually not a star but the ringed planet Saturn.

January 7: If you’re an early riser, take a look at the Moon and you’ll see what appears to be bright star just below it. Well, that’s actually not a star but the ringed planet Saturn.

January 9

Again, the Moon has moved along in its orbit, and is now quite distant from both Spica and Saturn. This morning it appears near the red star Antares, the brightest star in the constellation Scorpius. Antares is a red supergiant star about 883 times bigger than our Sun, located about 470 light-years from us.

January 10

This morning the Moon, now a thin crescent, can be seen above what looks like a very bright star. Actually, it’s the planet Venus, low on the horizon. Venus will remain low in the east before dawn until the middle of February, when it will have moved too close to the Sun to be visible.

The Moon today will be at the closest point to Earth in its orbit, called perigee. The distance between the two bodies today will be 360,046 kilometres.

January 12

New Moon occurs today at 6:44am Sydney time (19:44 Universal Time on January 11).

January 14-27

If you have dark skies and are a little bit lucky, you might spot a few meteors between these dates, emanating from the southern sky. The Eta Carinid meteor shower occurs at this same time every year, but it’s not a very good one compared with others – you might be lucky to see a few meteors per hour, between midnight and dawn.

January 19

It is First Quarter Moon today at 10:45am Sydney time (23:45 Universal Time on January 18). First Quarter is a good time to look at the Moon through a telescope, as the sunlight angle means the craters and mountains are throwing nice shadows, making it easier to get that 3D effect.

January 21: The Moon, Jupiter and the Pleiades star cluster will all be close together in the evening sky.

January 21: The Moon, Jupiter and the Pleiades star cluster will all be close together in the evening sky.

January 21

In tonight’s evening sky, the Moon will be situated quite near a famous cluster of stars, called the Pleiades or Seven sisters. When the Moon is not around and the sky is dark, most people can make out 6 to 7 of the Pleiades stars, although eagle-eyed stargazers can see a few more. With the Moon tonight being more than half full, it might be a little harder to see them. But if you have a pair of binoculars or a small telescope, take a look and you’ll be rewarded with a lovely sight – there are actually hundreds of stars (only some of them are visible through small optical instruments) in this beautiful “open star cluster“, and it is also filled with beautiful whispy gas clouds, although the stars and the gas are not actually related to each other—we just happen to be seeing them at a time when the stars are drifting through the gas.

And what’s that bright object just to the right (east) of both the Moon and the Pleiades? That’s actually the planet Jupiter.

January 22

Today the Moon will reach the farthest point from Earth in its orbit, apogee, at a distance of 405,312 kilometres. Take a look at it, and you’ll see what looks like a bright star just above it – it’s actually the planet Jupiter, the largest planet in our Solar System. Even a pair of binoculars will begin to show its size and shape, as well as up to four of its moons. A small telescope will reveal the different cloud bands that colour its upper atmosphere.

January 27

Full Moon occurs today at 3:38pm Sydney time (04:38 Universal Time).

There’s more great night sky viewing information at Melbourne Planetarium’s Skynotes site.

If you have any questions or comments on the night sky, we’d be happy to answer them. Please use the Feedback Form below. Happy stargazing!

Images courtesy IAU.

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