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January 2015: Out There

January 2015

In the show this time, we talk to Dr. Jill Tarter about the search for extraterrestrial intelligence (SETI), Ian Harrison rounds up the latest news, and we find out what we can see in the January night sky from Ian Morison and Claire Bretherton.

The News

This month in the news: Mars belches, and the Planck spacecraft mimics van Gogh.

Scientists reported that NASA's Curiosity Rover on Mars has detected a significant short term spike in the amount of methane (an organic molecule closely associated with the presence of life) in the Martian atmosphere.

Speaking at the American Geophysical Union Fall Meeting, the scientists described how, over a period of 60 Martian days (which is approximately the same number of Earth days), instruments on the rover observed the amount of methane in the local atmosphere climb to a level of 7 parts per billion, ten times its background value of 0.7 parts per billion, before falling back again. Though methane has been observed in Mars' atmosphere from both the Earth and the Mars Express orbiter for around 10 years, Curiosity is the first to detect the gas from the surface of the planet itself.

As methane is broken down by the harsh ultraviolet radiation that continually bombards the Martian surface, the continued detection suggests the gas is being somehow replenished, but the source of the gas is unclear. Here on Earth, the presence of methane is strongly correlated with the presence of organic life. About 95% of the methane in the Earth's atmosphere produced by living things. The prospect that the gas on Mars could be being produced by alien life forms is, of course, highly exciting. However, a number of other mechanisms are capable of producing the gas without the need for little green cows. Reactions between the water-ice (strongly suspected to exist below the surface of Mars) and olivine rocks in the Martian crust could create sub-surface stores of the gas, which could be released by geological activity. This explanation fits with the sharp spike in concentration seen by the rover.

Other results from Curiosity published in Science last month describe the detection of additional other organic molecules by the Sample Analysis at Mars (SAM) instrument. In this instance, chlorine-containing carbon compounds were discovered in a piece of rock, named "Cumberland", drilled from the Martian surface in 2013. The SAM instrument cooked part of this sample in its oven and analysed the gases produced, finding the complex molecules chlorobenzene, dichloroethane, dichloropropane and dichlorobutane, all of which are strongly associated with the presence of life here on Earth. However, these molecules can also be produced by non-biological processes as well.

Taken together, these two discoveries add to the list of scientific tests that are consistent with but not proof of the presence of current or past of life on Mars. More light should be shed on the situation by the Mars 2020 rover, which will also aim to return rock samples for more detailed investigation on Earth, or, of course, the appearance of friendly aliens in your back garden.

In other news, the European Space Agency's Planck spacecraft released its first results on polarised emission from the cosmic microwave background at the Planck 2014 conference in Ferrara, Italy.

The Planck team do not yet feel confident enough in their analysis to comment on the much talked-about result from the BICEP2 experiment, whose claim of detecting a twirl in the pattern of the cosmic microwave background polarisation earlier this year have been discredited by many as being likely caused by contaimination by dust within our own galaxy. However, they did present analysis of the polarisation data, which allowsthem to form constraints on cosmological parameters that are now far less dependent on the findings of the now-retired WMAP satellite. Planck's measurements of these cosmological parameters support with greater precision than ever our picture of the universe as a whole consisting of dark matter, dark energy and ordinary matter.

In addition to these analysis results, a striking new visualisation of the polarisation data was presented, which listeners are highly encouraged to view in this Physics World article on the results. In the image, colours show the thermal emission of galactic dust, whilst relief shows the galaxy's magnetic field. The result is a quite beautiful replication of the thick-paint 'Impasto' style used by Vincent van Gogh on his impressionist paintings of the night sky.

Interview with Dr. Jill Tarter

Dr. Jill Tarter holds the Bernard M. Oliver Chair for SETI Research at the SETI Institute in California. She has spent majority of her professional career attempting to determine whether we are alone in the universe, and among her other prior positions, she was the Project Scientist for NASA's SETI program. In this interview, Dr. Tarter tells us about the latest in SETI research, including what we can expect the Square Kilometer Array to contribute to SETI.

The Night Sky

Northern Hemisphere

Ian Morison tells us what we can see in the northern hemisphere night sky during January 2015.

Orion is high in the south, pointing to other nearby constellations. Below Orion's famous Belt is his Sword, in the middle of which is the hazy glow of the Orion Nebula. This is an HII region in which stars are being born, and it is lit by the four stars of the Trapezium at its heart. Following Orion's Belt down to the left, you come to the brightest night-time star, Sirius. Following the Belt in the other direction brings you to the constellation of Taurus the Bull. The Hyades Cluster forms its head, while the red star Aldebaran represents its eye. A little further over is the Pleiades Cluster. Up to Orion's left is Gemini, the Twins, with the bright stars Castor and Pollux. Near the zenith is the yellow star Capella, in Auriga. The Milky Way runs through Auriga, giving it a number of open star clusters that can be seen with binoculars. Perseus and Cassiopeia lie north-west from here, along the Milky Way, with the Perseus Double Cluster between them. Leo the Lion rises in the east late in the evening, hosting the planet Jupiter at present.

The Planets

  • Jupiter, at magnitude -2.4, rises around 20:00 UT (Universal Time) at the beginning of January and is located 8.5° up and right of the star Regulus in Leo. It is moving retrograde (westward) towards Cancer, which it will reach next month, and by the end of January it rises at 17:45 and shines at magnitude -2.6. It then reaches a maximum elevation of 56° when due south around 01:00. Jupiter's apparent size grows from 43.4 to 45.3" during the month, and its equatorial bands and Great Red Spot are visible to a telescope, while observing its four largest moons requires only binoculars.
  • Saturn rises at about 05:00 UT at the start of the month and 03:30 by its end. It moves from Libra into Scorpius on the 4th, moving above the star Antares and the head of Scorpius. It grows from 15.5 to 16.1" during January, ending the month at magnitude +0.6 and high enough in the south-east before dawn to allow a telescope to make out its rings, which are now 24° to our line of sight.
  • Mercury is low in the south-west before dawn on New Year's Day, 3° down to the right of Venus and shining at magnitude -0.8. Mercury and Venus then stay within 1° of each other from the 8th to the 12th. Mercury's gibbous disc is 6.5" across, and it reaches greatest eastern elongation east (its furthest from the Sun in the sky, on this occasion 19° away) on the 14th. Over the following week, it wanes in phase and drops to the lower right of Venus, disappearing from view as it moves between the Earth and Sun (inferior conjunction) on the 30th.
  • Mars starts the month in Capricornus and moves into Aquarius on the 8th. It dims slightly from magnitude +1.1 to +1.2 during January, while its disc shrinks from 4.8 to 4.4". It is best observed as darkness falls, low above the south-western horizon, but its small size and low elevation prevent surface details from being seen. Mars lies 24° up and left of Venus as the year opens, and sets around 3 hours after the Sun all month as it progresses eastwards relative to the stars.
  • Venus shines at magnitude -3.9 and, as the month begins, sets in the south-west just over an hour after the Sun. Its angular size increases from 10.3 to 10.8" during January; Earth's atmosphere blurs its disc, but may also split its colours to produce a spectrum that can be seen with a telescope.
  • Highlights

    Southern Hemisphere

    Claire Bretherton from the Carter Observatory in New Zealand speaks about the southern hemisphere night sky during January 2015.

    The Earth reaches its annual perihelion (its closest to the Sun) on the 4th, but the extra solar radiation has only a small effect compared to the seasonal tilt of the planet's axis. With the summer solstice passed, the nights gradually begin to grow longer, and the Milky Way stretches across the eastern sky after dark. The brightest area is towards the Galactic centre, near the constellation of Crux, which to Māori is Te Punga, or the Anchor. Also known as the Southern Cross, Crux is near to the asterisms of the Diamond Cross and the False Cross. Canopus, the second-brightest star in the night sky at magnitude -0.7, sits above the Milky Way and never sets over New Zealand. It is known to Māori either as Ariki, meaning high-born, or as Atutahi, meaning stand-alone, and is considered Tapu, or sacred. Canopus is the brightest star in the constellation of Carina, the Keel, which once formed part of the great constellation of Argo Navis. This area of the sky hosts many nebulae and star clusters, including NGC 3372, the Carina Nebula. A huge cloud of glowing gas, it is one of the largest nebulae in our sky, and its bright centre is visible to the naked eye. Binoculars can pick out Eta Carinae, the golden star at the heart of the nebula, which is actually a system of two known stars. With a total combined luminosity of some five million times that of our Sun, these stars are very large, the bigger of the two barely held together by gravity as its intense radiation pushes outwards and drives a stream of material into space. Eta Carinae has changed brightness greatly over the last 350 years, varying from magnitude +4 in 1677 to -0.8 in 1843. Now back at around 4, it seems to be brightening once again, and the variation is believed to result from sudden outbursts of material.

    Eta Carinae is part of the huge open star cluster Trumpler 16, which contains many young stars. The nearby open cluster Trumpler 14 is currently forming massive stars. IC 2602, known as the Theta Carinae Cluster or the Southern Pleiades, is about 4° south of Carina. Home to around 60 stars and covering an area greater than that of the full Moon, its magnitude of +1.9 makes it a good target for the wide field of a pair of binoculars. NGC 2516 and NGC 3532 are other naked-eye open clusters in Carina that look spectacular in binoculars.

    The Planets

    Highlights

    Odds and Ends

    Nine years after launch, the New Horizons spacecraft has now woken up in preparation for its flyby of Pluto in July. Launched before Pluto was reclassified as a dwarf planet, the mission will use its suite of scientific instruments to examine Pluto and its satellites and will take close-up photographs of the surface for the first time. With no main engine, New Horizons will speed past Pluto at a speed of 14 kilometres per second. At its closest approach, the spacecraft will be 10,000 kilometres from the surface. After the encounter, the extended mission will hopefully see minor course corrections to take the spacecraft past other Kuiper Belt Objects and eventually into interstellar space. More information is available from the NASA press release.

    The Atacama Large Millimeter/submillimeter Array and Combined Array for Research in Millimeter-wave Astronomy recently observed cold molecular gas in the centre of NGC 1266, which is a relatively nondescript lenticular galaxy. This gas would normally be the fuel used to form stars, but astronomers discovered that the gas is being churned up by jets from a supermassive black hole at the centre of the galaxy. While this phenomenon is expected in active galactic nuclei like quasars that produce really strong jets as well as very strong X-ray and radio emission, it is somewhat surprising to discover the phenomenon within a much fainter object. More details are provided in the press release.

    NASA's NuSTAR X-ray telescope has taken a break from observing black holes in other galaxies to look at our own Sun for the first time. NuSTAR is able to image the Sun without damaging itself and may be able to solve mysteries such as why the Sun's outer corona is hotter than its 'surface' or photosphere. Its mission has been extended to 2016, during which time it will look at the Sun, objects within the Milky Way and distant galaxies.

    Show Credits

    News:Ian Harrison
    Interview:Dr. Jill Tarter and Prabu Thiagaraj
    Night sky:Ian Morison and Claire Bretherton
    Presenters:Megan Argo, George Bendo, and Mark Purver
    Editors:Mark Purver, Ben Shaw, and Prabu Thiagaraj
    Segment Voice:Iain McDonald
    Website:George Bendo and Stuart Lowe
    Cover art:An artist impression of the central region of NGC 1266, where jets from the central black hole are creating turbulence in the surrounding molecular gas. CREDIT: B. Saxton (NRAO/AUI/NSF)

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