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September 2010: Kinky

September 2010

In this show Jonathan Pearson, a PhD student at JBCA, tells us about theoretical cosmology and his work trying to explain the Universe using domain walls and kinky vortons. As always, we have the latest astronomical news, and what you can see in the September night sky in the northern and southern hemispheres.

The News

In the news this month:


Over the past 10 years or so, astronomers have discovered that most of the energy in the Universe takes forms that we don't understand. There are two different labels for our ignorance; dark matter and dark energy. Dark matter is stuff within galaxies that adds extra gravity to keep them together. Dark energy seems to be making galaxies in the Universe accelerate away from each other like a form of anti-gravity.

Jonathan Pearson describes one of the speculative, theoretical models - kinky vortons - that might explain the cause of dark energy. A kinky vorton is a domain wall; the boundary between two regions of space with different characteristics. A domain wall would be incredibly thin, contain huge amounts of energy and repel matter. Jonathan and Stuart talk about the properties of domain walls and how you might look for them in the Universe.

The Night Sky

Northern Hemisphere

Ian Morison tells us what we can see in the northern hemisphere night sky during September 2010.

The nights are drawing in. Overhead in the south after sunset are Cygnus the Swan, Lyra the Lyre and Aquila the Eagle. Their respective brightest stars, Deneb, Vega and Altair make up the Summer Triangle. A third of the way up from Altair to Vega, the dark patch of sky known as the Cygnus Rift can be seen through binoculars. It is a dust cloud obscuring the starlight beyond, and contains the asterism Brocchi’s Cluster, often called the Coathanger. The constellatiof Pegasus, the Winged Horse, is low and inverted in the south-east, near to our neighbouring giant galaxy, M31, located in the Andromeda constellation and bearing the same name. The galaxy can be found by curving two stars up and left of the top left corner of the Square of Pegasus, which is the star Alpha Andromedae, then moving two stars to the right. It appears as a hazy glow in binoculars or, in a dark sky, to the unaided eye. The Andromeda galaxy is 2.5 million light years away, and may be around 20% more massive than our Milky Way. Andromeda and the Milky Way are the two largest galaxies in the Local Group. The constellations of Cassiopeia and Perseus rise in the east, beneath the band of the Milky Way. The Perseus Double Cluster lies between them, visible to the naked eye, distinguishable with binoculars and full of stars through a telescope.

The Planets


Southern Hemisphere

John Field from the Carter Observatory in New Zealand speaks about the southern night sky during September 2010.

Jupiter returns to the evening sky this month, rising in the east after sunset. Named after the King of the Greek gods, the largest of the Solar System’s planets takes 12 years to orbit the Sun, passing through one zodiacal house roughly every Earth year in our sky. In Māori, it is called Pareārau or Kōpū-nui. Galileo observed Jupiter’s disc and four largest moons in the 17th century, the moons ranging from 3000 to 5000 km in diameter. Io is the nearest of these to Jupiter, and is the most volcanically active body in the Solar System due to gravitational friction from the objects around it. Europa is the smoothest object in the Solar System, probably containing water under an ice layer many kilometres thick, and may be capable of supporting life. Ganymede and Callisto are the outermost of the four main moons, which are among a total of 63 known to orbit Jupiter. Galileo also observed bands of cloud on the planet, one of which contains the Great Red Spot, a storm 2.5 times the diameter of the Earth that has be seen continuously for 200 years. Jupiter, at 318 times the mass of the Earth, outweighs all the other planets in the Solar System together. Venus, the Evening Star, appears in the west after sunset. Mars, fainter, sits below. The star Vega shines on the northern horizon, while the Milky Way spans the sky from north to south. The orange star Antares, the heart of the constellation Scorpius, is overhead to the west. The Scorpion’s tail, or hook of Māui to the Māori, curls towards the zenith, while the Southern Cross and its pointers lie in the south-west. Beyond Scorpius’ tail is Sagittarius, often named the Teapot after the shape of its brightest stars. Sagittarius, the Archer, is said to be firing an arrow at Scorpius in revenge for its killing of Orion the Hunter. Aquila, the Eagle, is north along the Milky Way. Its brightest star, Altair, referred to as Poutū-te-rangi by Māori astronomers, is the twelfth-brightest in our sky and one of the closest at 16 light years distant. Imaging reveals that this star spins rapidly enough to make it noticeably oblate. Altair, Vega in Lyra and Deneb in Cygnus form what is known in the southern hemisphere as the Winter Triangle, which is the Summer Triangle to those in the northern hemisphere. Canopus, the second-brightest star in the sky, is low in the south. The navigator of Spartan King Menelaus in Greek mythology, to the Māori it is Atutahi, chief of the heavens. It appears as a circumpolar star from New Zealand, and was once called Alpha Argos, part of the constellation Argo, the great ship of Jason in Greek mythology. This constellation has since been divided into three, and Canopus is known as Eta Carinae, the brightest star in Carina, the ship’s keel. The Hipparcos satellite measured Canopus to be 310 light years from Earth, with a mass 8.5 times that of our Sun and outshining it by a factor of 15,000. Carina contains a number of star clusters. One of these, IC 2602, known as the Southern Pleiades, is a degree across and surrounds the 3rd magnitude star Theta Carinae. Binoculars reveal its many stars. Nearby, NGC 3532 is visible to the naked eye as a haze near the Eta Carinae Nebula. A favourite of John Herschel, it contains 150 stars and covers one degree of sky, twice that of the full Moon. With a telescope, a number of small lines and orange stars can be seen. NGC 2516, another open cluster, can be seen by eye on a moonless night. Its scattered groups of stars can be seen through binoculars or a telescope, and three bright orange stars stand out within it.


Odds and Ends

NASA are asking members of the public to pick the wake-up songs for the final space shuttle missions. You can choose from a list of 40 previous wake-up songs for STS-133 and write and submit your own song for STS-134

Roy explains how pulsars have been used to weight the planets in our Solar System.

The discovery of multiple exoplanets around a star have been announced by two teams. The ESO HARPS instrument has detected 5 Neptune-like planets around the star HD 10180 and has found evidence that there may be a further 2 planets in this system, one of which would be 1.4 times the mass of the Earth. The NASA Kepler mission has announced the discovery of two Saturn-like planets around the star Kepler-9, with the possibility of a third planet 1.5 times the size of the Earth.

The Big Bear Solar Observatory has released the most detailed visible light image of a sunspot.

The Jodcast team went on a somewhat crazy mission during August, visiting all 7 of the telescopes in the eMerlin array in a day. The trip was filmed for a future Jodcast video, but short clips from the day are up on Youtube.

On the 26th August, the hashtag #astromovies was born on Twitter. A couple of people blogged about it and Dr Paul Woods from JBCA has compiled a full list. Some of our favourites include Gone with the Solar Wind, Lord of the Ring Nebula and Jod-Castaway.

In reponse to the Ask an Astronomer question on black holes in the August 2010 Extra show, listener EarthUnit has posted a link on the forum to a lecture on black holes by Professor Alex Filippenko.

Finally, the School of Atmospheric Science at the University of Manchester have started up their own podcast called The Barometer.

Show Credits

News:Megan Argo
Interview:Jonathan Pearson and Stuart Lowe
Night sky:Ian Morison and John Field
Presenters:Jen Gupta and Roy Smits
Editors:Jen Gupta, Claire Bretherton, Stuart Lowe and Mark Purver
Big Brother Voiceover Man:Stuart Lowe
Intro/outro editor:Fiona Thraille
Intro/outro music:'Techno Borealis' by Adam Spitzer available at Newgrounds
Segment voice:Lizette Ramirez
Website:Stuart Lowe and Jen Gupta
Cover art:God takes a bath and you are here - on the edge of a cosmic soap bubble. Bubbles turn out to be a pretty good model for the clumpiness of matter -- lots of stuff along the edges and not much else in between. Credit: woodleywonderworks (Flickr)

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