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August 2012: A Ring To It

August 2012

In the show this time, Dr Fergus Simpson tells us about mapping dark matter using weak gravitational lensing and Professor Carlos Frenk talks about exploring the nature of dark matter through simulations. Megan summarises the latest astronomy news and we find out about the August night sky from Ian Morison and John Field.

The News

In the news this month:

Interview with Dr Fergus Simpson

Dr Fergus Simpson, from the Royal Observatory Edinburgh, talks to us about CFHTLenS, a wide field survey done with the Canada-France-Hawaii Telescope, focusing on mapping dark matter using gravitational lensing techniques. As light from galaxies travels towards us, it is deflected by matter on its way. By doing a statistical study of the deformation in the shapes of galaxies, a team of astronomers from France, Canada, Hawaii and the UK were able for the first time to produce a large map of the distribution of dark matter in our Universe.

Interview with Prof. Carlos Frenk

Prof. Carlos Frenk is Director of the Institute for Computational Cosmology at Durham University, and works on some of the world's largest and most sophisticated simulations of the evolution of structure in the Universe. He gave a plenary talk at the National Astronomy Meeting on testing the Lambda-CDM cosmological model by observing the dwarf satellite galaxies that orbit large galaxies. Here, he explains that the observed numbers, sizes and distributions of satellites around large galaxies do not fit with those predicted by simple Lambda-CDM simulations, leading to two possibilities: either the simulations need to include more physics than just the force of gravity, or the dark matter particles are 'warm' (i.e. more energetic) rather than cold. Prof. Frenk also provides insight into how computer simulations of the Universe work, and why there can be more than one approach to solving a single set of physical equations. He talks about how simulations can now reproduce stars and galaxies, and speculates as to how far they may eventually go.

The Night Sky

Northern Hemisphere

Ian Morison tells us what we can see in the northern hemisphere night sky during August 2012.

Arcturus, in Boötes, is setting in the west in the evening. Corona Borealis and Hercules are to the south, the latter containing the globular cluster M13 on the right-hand side of the four stars of the Keystone. Overhead, the Milky Way passes through the Summer Triangle which consists of the bright stars Vega, Deneb and Altair in the constellations of Lyra, Cygnus and Aquila respectively. The Square of Pegasus is rising upside-down in the east. Following the Milky Way north from Deneb, we reach Cassiopeia, and then Perseus towards the northern horizon. Many objects, such as the Double Cluster, can be seen between these two constellations.

The Planets

Highlights

Southern Hemisphere

John Field from the Carter Observatory in New Zealand speaks about the southern hemisphere night sky during August 2012.

Scorpius and Crux are high in the evening sky, running along the path of the Milky Way which stretches from east to west. A number of avian constellations cluster around the south celestial pole. Pavo, the Peacock, contains the bright star Alpha Pavonis and the nearby Sun-like star Delta Pavonis, as well as the barred spiral galaxy NGC 6744. The galaxy is similar in structure to the Milky Way, and, at magnitude +9, can be seen as a haze using a small telescope, while larger telescopes reveal its spiral arms. Pavo also contains the globular cluster NGC 6752, the third-brightest globular cluster in the night sky, which, at magnitude +5.4, is just visible to the naked eye under a dark sky. Binoculars or a telescope may reveal curved lines and loops of stars. Nearer to the south celestial pole is Apus, the Bird of Paradise, which contains a double star of magnitude 4.6 called Delta Apodis. It consists of a red and an orange star which may be connected but are not gravitationally bound, as they are at different distances from us. A telescope of 20 centimetres in diameter reveals the 9th magnitude globular cluster NGC 6101 in Apus. Tucana, the Toucan, sits near Pavo. It hosts a spectroscopic binary star, Alpha Tucanae, which has an orbital period of 11.5 years and a magnitude of +2.8. The star Beta Tucanae is a group of six stars bound loosely together by gravity. The dwarf galaxy known as the Small Magellanic Cloud (SMC) resides in Tucana, and looks like an indistinct cloud to the naked eye. Appearing next to it is the brightest globular cluster in the sky, 47 Tucanae. It looks like a fuzzy star to the unaided eye, but in fact contains millions of stars and makes a stunning sight in binoculars.

Highlights

Odds and Ends

Astronomers using NASA's Spitzer Space Telescope have detected what they believe is a planet two-thirds the size of Earth. The exoplanet candidate, called UCF-1.01, is located a mere 33 light-years away, making it possibly the nearest world to our solar system that is smaller than our home planet.

MediaCity, in Salford, will be hosting a NASA event, streaming the landing of the Mars Rover Curiosity live onto a big screen. The event is open to the public and the screening begins at 5am on Monday the 6th of August.

The Defence Advanced Research Project Agency, a US governmental organisation, is hoping to start a project called Phoenix, which will ultimately use a number of mini-satellites to harvest useful components from defunct communication satellites and use them to create new, functioning satellites, all whilst in orbit around the Earth. As Universe Today puts it: "Frankensatellites anyone?"

Show Credits

News:Megan Argo
Interview:Dr Fergus Simpson and Melanie Gendre
Interview:Prof. Carlos Frenk and Mark Purver
Night sky:Ian Morison and John Field
Presenters:Adam Avison, Liz Guzman and Christina Smith
Editors:Mark Purver, Megan Argo, Claire Bretherton, Melanie Gendre and Liz Guzman
Segment Voice:Cormac Purcell
Website:Mark Purver and Stuart Lowe
Producer:Mark Purver
Cover art:NASA's Mars rover, Curiosity, which will land on the red planet this month. CREDIT: NASA/JPL-Caltech

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