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October 2014: Closer

October 2014

In this show, we talk to Dr Alan Duffy about simulating the earliest galaxies, Indy rounds up the latest news and we find out what we can see in the October night sky from Ian Morison and Claire Bretherton.

The News

In the news this month: complex molecules, and clear skies.

Interview with Dr Alan Duffy

Dr Alan Duffy works at Swinburne University in Melbourne, using cosmological simulations to study galaxies and the large-scale structure of the Universe. He tells us about his PhD at the Jodrell Bank Centre for Astrophysics, in which he was looking at gravitational simulations of dark matter, and he explains how this can model the behaviour of the Universe even though we don't really know what dark matter is. He then moves on to his current work on hydrodynamical simulations, in which 'normal' matter is added to the mix, creating gas flows and supernovae for a more realistic picture. He discusses how the results of these simulations will inform the aims of the Square Kilometre Array radio telescope, and explains that they suggest that a population of small galaxies was partly responsible for reionising the hydrogen in the Universe with the first stars. Alan also talks about his extensive astronomy outreach work in Australia.

The Night Sky

Northern Hemisphere

Ian Morison tells us what we can see in the northern hemisphere night sky during October 2014.

The constellations of Cygnus, Lyra and Aquila are almost overhead in the evening, with their bright stars Deneb, Vega and Altair forming the Summer Triangle. The Square of Pegasus is to the lower left of Cygnus. If you move from its top-left to the next bright star, fork a little to another star and go the same distance again, before turning sharply right to find another star, then carrying on a little further brings you to the fuzzy glow of the Andromeda Galaxy. If you go back to the sharp right turn and carry on the same distance again, binoculars may pick up the Triangulum Galaxy as well. Andromeda can also be found by moving along the Milky Way from Deneb to the W-shape of the Cassiopeia constellation and following the V of the three highest stars like an arrow. Moving a bit further along the Milky Way, and dropping down between two stars towards Perseus, you can locate the beautiful Double Cluster.

The Planets


Southern Hemisphere

Claire Bretherton from the Carter Observatory in New Zealand speaks about the southern hemisphere night sky during October 2014.

The winter constellation of Scorpius (Te Matau a Māui to Māori) is dropping towards the western horizon, and sets by midnight NZDT (New Zealand Daylight Time, 13 hours ahead of Universal Time). Meanwhile, Orion is rising in the east, along with the other summer constellations of Taurus and Canis Major. Mercury can still be spotted low in the west-south-west during the first week of October, while Saturn is below Scorpius and sets around 22:00 NZDT. Mars continues to hang halfway up the western sky after dark. Comet Siding Spring C/2013 A1 passes within 138,000 kilometres of Mars on the 19th-20th, and may be visible in binoculars from Earth. Approaching Mars from above as seen from the southern hemisphere, it is 4.4° away on the 15th, then passes beneath it and moves to the lower left of the globular cluster NGC 6401 on the 20th. Uranus is in Pisces, to the north-east, and Neptune is in Aquarius, higher in the north, but neither can be seen with the naked eye. Jupiter is the brightest planet currently in the sky, and rises in the north-east around 04:30 NZDT at the beginning of the month, its largest moons visible in binoculars.

Pegasus, the Winged Horse, straddles the northern horizon in the evening. Identified by a large square of stars, its brightest member is the orange supergiant Epsilon Pegasi, or Enif, named after the Arabic word for the Horse's nose. Nearby is the M15, which may be the densest globular cluster in our Galaxy. With a magnitude of +6.2, it appears as a fuzzy glow in binoculars, while a telescope can pick out chains of stars radiating out from the core. M15 also contains the planetary nebula Pease 1, the first such object to be found within a globular cluster. At magnitude +15.5, a telescope of 30 centimetres in aperture is required to see it. Alpheratz, the star at the bottom of the Great Square of Pegasus, is a great place from which to star-hop to the Andromeda Galaxy, which appears near the northern horizon in southern hemisphere skies only at this time of year. To find it, move along the uppermost of two chains of stars that extend east from Alpheratz, pass Delta Andromedae, turn sharp right at Mirach, carry on to Mu Andromedae and then go the same distance again to the galaxy. At 2.5 million light-years' distance, it is the most distant object normally visible to the naked eye from Earth.


Odds and Ends

On the November 2013 Extra episode of the Jodcast, we mentioned the launch of the Mars Orbiter Mission (also nicknamed Mangalyaan) by the Indian Space Research Organisation. On 24 September, Mangalyaan entered into orbit around Mars. This was India's first interplanetary space mission ever, and it is also remarkable given the relatively low budget (4.5 billion rupees, equivalent to 74 million US dollars or 45 million British pounds) and given that both the United States and the former Soviet Union failed in their first Mars space missions. The spacecraft only weighs 15 kilogrammes and contains a relatively limited amount of instrumentation, but it will play a key role in searching the Martian atmosphere for methane, which could be an indicator of biological activity on the planet. More information is available from the BBC article announcing the success of the spacecraft entering orbit as well as an additional BBC analysis of the mission.

NASA's Cassini spacecraft has spotted another mysterious wave-like feature on the surface of one of Titan's seas. This follows the earlier discovery of a similar feature on Saturn's largest moon in July 2013, which had since disappeared. Its reappearance is interesting as it implies that the feature observed in July was neither a transient phenomenon nor an instrumental flaw. Scientists at NASA will continue to monitor Titan's seas for waves.

The evidence for gravitational waves in the early Universe is looking a little shakier following new analysis of the cosmic microwave background (CMB). Earlier this year, the BICEP2 mission released data from the CMB that appeared to show the polarised patterns expected to have been caused by gravitational waves that were stretched by cosmic inflation in the first moments after the Big Bang. However, the signature could also be caused by foreground emission such as spinning dust in the Milky Way, and BICEP2 could not gather the information necessary to subtract that signal. The most recent findings of the Planck mission show that such a foreground has contaminated the BICEP2 data, but it is not yet clear whether this can fully explain the observations or whether the signature of inflation may yet remain after it is subtracted.

Show Credits

News:Indy Leclercq
Interview:Dr Alan Duffy and Mark Purver
Night sky:Ian Morison and Claire Bretherton
Presenters:George Bendo, Fiona Healy and Mark Purver
Editors:Adam Avison, Claire Bretherton, Sally Cooper, Indy Leclercq and Mark Purver
Segment Voice:Tess Jaffe
Website:Mark Purver and Stuart Lowe
Producer:Mark Purver
Cover art:The first image of Mars taken by the Mars Orbiter Mission. CREDIT: Indian Space Research Organisation

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