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.
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.
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
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.
- Mercury and Venus appear just 39' apart after sunset on the 10th, low in the south-west. Mars is found higher and further south at the same time.
- Saturn is 3.5° to the lower left of a waning crescent Moon an hour before dawn on the 16th.
- A waxing gibbous Moon can be seen about 1° up and left of the star Aldebaran and the Hyades Cluster after sunset on the 29th, having passed in front of them earlier in the day.
- The night of the 29th is a good time to observe the lunar craters Tycho and Copernicus using binoculars or a telescope. Tycho, the younger crater at around 108 million years old, is towards the bottom of the Moon in the Southern Lunar Highlands and may have been made by the impact of a Baptistina Family asteroid. It is 85 kilometres across and nearly 5 kilometres deep, and the rays of material shed by the impact can be seen arcing across the Moon's surface. Copernicus, some 800 million years old, lies in the easterly Oceanus Procellarum, beyond the end of the Apennine Mountains. It is a terraced crater, 93 kilometres wide and almost 4 kilometres deep. The Moon can be imaged very well using relatively simple equipment and processing.
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.
- Brilliant Venus follows the Sun in the sky, setting around an hour after it throughout January.
- Mercury follows the Sun even more closely, and appears near to Venus in the south-western twilight for the first half of the month. It reaches eastern elongation (its greatest separation east from the Sun in the sky) on the 15th, before rapidly disappearing in the Sun's glare until next month. Due to their proximity to the Sun, Mercury and Venus never stray far from it in our sky, always appearing shortly before dawn or after nightfall.
- Red Mars is above and to the right of Venus and Mercury, and approaches Venus during the month. At a present distance of around 300 million kilometres from Earth, its disc appears tiny in a telescope. It sets at about 23:30 NZDT (New Zealand Daylight Time, 13 hours ahead of Universal Time) at the beginning of January, but by the end can only just be seen only as daylight vanishes.
- Jupiter becomes more prominent in the evening sky this month, rising in the east-north-east at 23:00 NZDT at the start and at 21:00 at the end.
- Saturn is a pre-dawn object, but rises ever earlier in the east-south-east as January progresses.
- Comet C-2014 Q2 (Lovejoy) is brightening in the southern sky. First spotted at magnitude +15 in Puppis by amateur astronomy Terry Lovejoy, it reached +6 in mid-December as it approached the Sun. Early in January, its position in the sky moves from Lepus to Eridanus and then to Triangulum, and it may just be visible to the naked eye in Taurus on the 10th, although the Moon will hamper viewing. Comet Lovejoy disappears from New Zealand's skies in mid-January as it progresses northwards.
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.
|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)|