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June 2012: Captured

June 2012

Captured. This month, we continue our feast of interviews from the National Astronomy Meeting. We talk to Dr Patrick Sutton about gravitational wave detection with LIGO, Dr Antonio Chrysostomou and Dr Mark Thompson tell us about the sub-millimetre camera SCUBA-2, and Professor James Dunlop brings us up to speed on sub-millimetre galaxies and the instruments used to observe them. Megan rounds up the latest news and we find out what's in the June night sky from Ian Morison and John Field.

The News

In the news this month:

Interview with Dr Patrick Sutton

Dr Patrick Sutton, from Cardiff University, works on gravitational wave detection with LIGO. LIGO is part of a network of ground-based interferometers looking for the tiny ripples in space known as gravitational waves, which are believed to exist all around us. Its two sites each host L-shaped vacuum tubes of several kilometres in length, along which laser beams are split, reflected back and forth repeatedly and finally recombined to produce destructive interference at a detector.

Dr Sutton explains how gravitational waves can change the interference pattern and so be detected, even when they alter the length of an interferometer tube by only one thousandth of the diameter of a proton. He talks about the sorts of cosmic events which should produce detectable waves, the way in which detection techniques have already been tested and how various interferometers all over the world will corroborate each other's measurements. These measurements will be complementary to those of pulsar timing arrays and future space-based interferometers, as these projects will observe gravitational wave of different frequencies. Dr Sutton explains how they will, collectively, allow astronomers to probe deeper into dark and energetic events within the Universe.

Interview with Dr Antonio Chrysostomou and Dr Mark Thompson

Dr Antonio Chrysostomou, from the Joint Astronomy Centre in Hawaii, and Dr Mark Thompson, from the University of Hertfordshire in the UK, work with the SCUBA-2 instrument, which is mounted on the James Clerk Maxwell Telescope. It is a bolometric camera, placed high up in the dry air of Mauna Kea in order to receive submillimetre electromagnetic wavelengths that are largely absorbed by water in the Earth's atmosphere.

Dr Chrysostomou describes the advanced receiver and refrigeration technologies used in SCUBA-2, giving wide-field images and sufficient sensitive to correct for variable atmospheric distortion. Dr Thompson explains what can be observed at these wavelengths, from molecular clouds made of very cold cosmic dust released by dying stars, which go on to form new stars, to debris discs, which go on to form planets. In particular, a neat quirk of nature means that SCUBA-2 can locate dusty galaxies both nearby and far away, because the redshift of the more distant galaxies brings their brighter emission into the submillimetre band. This allows astronomers to use the camera to investigate the roles of gas and dust in the formation of galaxies, stars and planets from the Milky Way back to the early Universe.

Interview with Prof. James Dunlop

Prof. James Dunlop, from the University of Edinburgh's Institute for Astronomy, talks to us about submillimetre galaxies and what information their study brings to our understanding of galaxy evolution. Using space telescopes such as Herschel, or larger ground-based instruments such as the brand-new SCUBA-2, we can observe these dust- and gas-filled monsters. As Prof. Dunlop explains, they are very active in star formation and are predecessors of the giant quiescent galaxies we observe in the local Universe.

The Night Sky

Northern Hemisphere

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

The constellation of Leo is setting in the west after sunset, with Mars below it. The brightest visible star is Arcturus, in the southern sky in Boötes. Corona Borealis is to its left. Continuing left, we reach Hercules, containing the Keystone asterism. Two thirds of the way up its right-hand side is the globular cluster M13, which is a fuzzy blob through binoculars but whose individual stars can be seen with a telescope. Rising in the east is the Summer Triangle of Vega in Lyra, Deneb in Cygnus and Altair in Aquila. Brocchi's Cluster, an asterism also know as the Coathanger, lies a third of the way from Altair to Vega. Ursa Major is overhead; within it, the second star in the handle of the Plough is a double named Mizar and Alcor. A telescope shows that Mizar is itself a double star. The right-hand stars of the Plough, Merak and Dubhe, point up towards Polaris, the North Star.

The Planets


Southern Hemisphere

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

The winter solstice occurs on the 20th of June, marked by the dawn rising of Matariki (the Pleiades) and the star Puanga (Rigel). These are important transitions in Te Maramataka, the Māori annual calendar. The south-eastern sky is dominated by Scorpius and Sagittarius, the former containing the red star Antares, representing the Scorpion's heart. Antares is the sixteenth-brightest star in the night sky and has a faint companion, which can just about be seen against Antares' glare using a small telescope. Scorpius is a fishing hook to Māori and some Polynesian cultures, with Rehua (Antares) as the eye of the Hook. Many star clusters and nebulae can be observed around Scorpius, as the Milky Way passes through it. The globular clusters M4 and NGC 6144 are near Antares, a number of double stars appear along the Scorpion's body, and the open clusters NGC 6231, M7 and M6 (the Butterfly Cluster) are near its stinger. Binoculars or a telescope will reveal the individual stars in these clusters. Sagittarius, a Centaur and an archer in Babylonian mythology, also plays host to many nebulae and star clusters. The Lagoon Nebula, M8, has a compact core of stars surrounded by nebulosity containing dark rifts and globules where stars are forming. The Trifid Nebula, M20, is nebulous, but a medium-sized telescope reveals dark lanes that cut it into three. The brightest stars in Sagittarius form an asterism called the Teapot, near the top of which is the globular cluster M22, one of the brightest in the night sky. Other nearby star clusters are M23, M24, M25 and M55. An irregular dwarf galaxy known as Barnard's Galaxy, or NGC 6822, also resides in Sagittarius. The constellation is in the direction of the Galactic centre, so the Milky Way is at its most prominent in this region of the sky. The Māori called it Te Ika Roa, the Long Fish.

The Planets


Odds and Ends

Venus is set to transit the Sun on the 5th-6th of June. If you live in the UK, you'll have to get up at sunrise on the 6th to see the last two hours. If you want to take part in a global citizen science project and follow in the footsteps of Captain Cook, check out Jodcast listener Grahame Bowland's attempt to measure the distance from the Earth to the Sun. You can take part by tweeting the time you observe Venus entering and leaving the disc of the Sun, and where in the world you are. The results you send will be used to calculate the astronomical unit live on the site as the event goes on. There is also a free smartphone app for a similar project. Whatever you do, make sure you observe the transit safely.

NASA has released an amazing video of the Sun using enhanced images from the Solar Dynamics Observatory. It highlights structure on the surface of the Sun, caused by convection and the magnetic field.

NASA released the results of its investigation of the Vesta asteroid by the Dawn spacecraft. Among other highlights, the orbiter discovered that Vesta resembles a planetoid in consisting of core, mantle and crust, and that it is responsible for 6% of Earth's meteorites. In August, Dawn will set off on a two-and-a-half-year journey to the dwarf planet Ceres, which is the largest of the asteroids.

The Dragon capsule, launched from the SpaceX Falcon 9 rocket, became the first commercial vehicle to dock with the International Space Station (ISS) on the 25th of May. The unmanned craft was captured by a robotic arm under the control of astronauts on the ISS, completing a milestone in the new era of commercial space flight. SpaceX intends future incarnations of the capsule to carry human crews.
Note: On the 31st of May, after recording, Dragon successfully splashed down in the Pacific Ocean and was retrieved.

A team from the Universities of Manchester and Cambridge will be hosting an exhibit all about ALMA at the Royal Society's 2012 Summer Science Exhibition in London from the 3rd to the 8th of July. The exhibit will be manned in part by some of the Jodcast team, so please come and say hello! As well as ALMA, there are teams representing the Herschel Space Observatory and cosmic ray experiments in the field of astronomy. There are also 18 other exhibits, covering all aspects of science from how animals see things to robots playing football!

Tickets are still available for the second of this year's Live From Jodrell Bank gigs on Sunday the 24th of June. Headlined by Paul Weller, the support acts will now include Craig Charles.

Show Credits

News:Megan Argo
Interview:Dr Patrick Sutton and Mark Purver
Interview:Dr Antonio Chrysostomou, Dr Mark Thompson and Mark Purver
Interview:Prof. James Dunlop and Melanie Gendre
Night sky:Ian Morison and John Field
Presenters:Adam Avison, Leo Huckvale and Mark Purver
Editors:Mark Purver, Adam Avison, Claire Bretherton and Melanie Gendre
Segment Voice:Cormac Purcell
Website:Mark Purver and Stuart Lowe
Producer:Mark Purver
Cover art:The SpaceX Dragon capsule, held securely by the International Space Station's robotic arm, Canadarm2. CREDIT: NASA/ESA

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