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November 2014: Interstellar

November 2014

In the show this time, we talk to Professor Jim Drake about whether Voyager 1 has really left the Solar System, Ian Harrison rounds up the latest news and we find out what we can see in the November night sky from Ian Morison and Claire Bretherton.

The News

In the news this month: simulated black holes and smelly comets.

Interview with Prof. Jim Drake

Professor Jim Drake works at the University of Maryland, studying magnetic fields in plasmas. In particular, he is interested in the phenomenon of magnetic reconnection around the Sun and elsewhere in space, which suddenly releases the energy trapped within magnetic fields. In this interview, Prof. Drake talks about recent measurements made by humanity's most distant explorers, the iconic Voyager space probes, which indicate that Voyager 1 has passed the heliopause. The heliopause marks the boundary between the flow of particles from the Sun known as the solar wind and the denser gas of the interstellar medium (ISM), and, as Prof. Drake explains, we now have a more detailed understanding of it. He discusses Voyager 1's measurements of plasma density, cosmic ray count, magnetic field strength and magnetic field direction, showing that the increase in density and the change in cosmic ray type seem to indicate that Voyager 1 crossed the boundary in 2012, even though the expected change in magnetic field direction did not occur. He is involved in producing complex simulations that suggest that the direction of the magnetic field should indeed change more slowly from that of the Sun to that of the ISM, and that the boundary is more porous to cosmic rays than previously thought. He talks about the cultural, as well as scientific, significance, of the Voyager missions, and sounds a warning to potential Mars astronauts about the dangers of energetic particles in interplanetary space.

The Night Sky

Northern Hemisphere

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

The four stars of the Square of Pegasus are in the south after dark, with the Horse's head and mane to their lower right. Just beyond the head is the globular cluster M15, visible in binoculars or a telescope. Starting at Alpheratz, the top-left star of the Square, you can find M13, the Andromeda Galaxy. The W-shaped constellation of Cassiopeia is almost overhead, and the V of the upper-right stars also points towards M31. Pisces is to the lower-left of Pegasus, with Aries further left still. Orion and Taurus rise higher in the sky as the night wears on, with the Pleiades Cluster climbing in the south-east and the Hyades Cluster to its lower-left. The red-orange star Aldebaran appears to be part of the Hyades, but is actually around halfway between us and the cluster. Orion is below Taurus, the three stars of his Belt pointing up towards Aldebaran and the brightest night-time star, Sirius. The lower-right star of Orion is the blue giant Rigel, while the upper-left is the red giant Betelgeuse. Coming down from Cassiopeia, along the plane of the Milky Way, you reach Perseus. It contains the Perseus Double Cluster, between Cassiopeia and the star Mirfak, and also hosts Algol, known as the Demon Star due to a periodic dip in brightness that results from the eclipse of one star by another in a binary system. Descending from Perseus, you get to the yellow star Capella in Auriga, with the three open star clusters of M38, M36 and M37 nearby. Further down is Gemini, rising in the east after nightfall, with the stars of Castor and Pollux representing the Twins and the open cluster M35 near to the feet of the figure of Castor.

The Planets

Highlights

Southern Hemisphere

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

As Scorpius sets in the west after dark, Orion, Taurus and Canis Major rise in the east. The red star Antares, in Scorpius, is just above the south-western horizon at 23:00 NZDT. Known to Māori as Rehua, it marks one of the four Pou, or pillars, holding up the Sky Father, Ranginui. The other Pou are Matariki (the Pleiades), Tautoru (Orion's Belt) and Takurua (Sirius), and line the eastern horizon in the late evening. Their rising positions are close to those of the Sun at the winter solstice, the equinoctes and the summer solstice respectively. Stretching between Orion and Scorpius is Te Waka o Tama-rereti, a canoe represented by the tail of Scorpius (also known as Te Waka o Mairerangi) at its front and Orion's Belt (Tautoru) at its stern, with Crux (Te Punga) and the Pointer Stars (Te Taura) as its anchor and anchor line. Tama-rereti was said to have been a man who sailed across the sky in his canoe, placing the stars from his Kete (basket) into the heavens to allow navigation on Earth. He then capsized the canoe and spilled the remaining stars to form the Milky Way, or Te Ikaroa. The Māori new year is celebrated at the summer solstice, when the bright star Atutahi (Canopus), the Ariki (high chief) of the heavens, pulls up the anchor and sets the canoe in motion across the sky. Canopus is midway up the south-eastern sky in the evening in November.

A little higher and further south are two fuzzy patches of light called the Large and Small Magellanic Clouds (LMC and SMC), a pair of dwarf galaxies neighbouring the Milky Way and each containing several billion stars. The LMC is the lower of the two, and young star clusters within it may be seen as small patches of light through binoculars or a telescope. Prominent among these is the Tarantula Nebula (also called 30 Doradus or NGC 2070), an active starburst region containing over 800,000 stars and protostars. It was here that the most recent supernova visible to the naked eye on Earth, SN 1987A, occurred. The SMC appears close to the globular cluster 47 Tucanae, but is actually over ten times further away from the Earth than is the cluster. 47 Tucanae is the second-brightest globular cluster in our sky at magnitude +4.9, and is visible to the naked eye when the sky is dark. A telescope reveals a dense core of over a million stars, surrounded by a sparser sprinkling of many more.

The Planets

Highlights

Odds and Ends

A short film has been produced as part of promotional material for ESA's Rosetta mission; a probe that started its journey to Comet 67P/Churyumov-Gerasimenko 10 years ago in order to study the composition and chemistry of the comet, testing theories for how water made its way onto planets. Titled 'Ambition', the sci-fi short is seven minutes set in a future world, where Rosetta is seen as one of the first stepping stones to finding out more about the origins of life. The aim is to reach a wider audience who may not otherwise know much about the purpose of the mission, and has been timed to generate additional interest before its robot lander Philae touches down on the comet this month. It can be found on ESA's website.

Astronomers working on the Frontier Fields programme have discovered one of the most distant objects ever seen: an object estimated to be 13 billion light-years away with a redshift of around 10. The object is thought to be a galaxy 500 times smaller than the Milky Way. It has been discovered due to gravitational lensing by a foreground galaxy cluster, which has magnified it to appear 10 times brighter. Astronomers believe the galaxy offers insight into the evolution of the early universe, which they hope will help them answer some of the fundamental questions of cosmology such as structure formation and evolution.

A Hasselblad 500C camera that flew on at least one of the Mercury missions is set to be autioned in November 2014. The estimated sale price is 50,000-100,000 in US dollars. The camera was originally bought, modified, and used by Wally Schirra on Mercury-Atlas 8, as confirmed by RR Auction of Massachusetts. It has also been stated that this camera was also used by Gordon Cooper on Mercury-Atlas 9, although that claim is in doubt. While it is now common for astronauts to now use cameras in space, it was not something that either space agencies or many astronauts thought about doing at the start of the space race. As one of the first cameras to be used by astronauts in space, it is a small piece of space history. More information can be found in the space.com article about the camera.

Show Credits

News:Ian Harrison
Interview:Prof. Jim Drake, Mark Purver and George Bendo
Night sky:Ian Morison and Claire Bretherton
Presenters:George Bendo, Josie Peters and Hannah Stacey
Editors:Ben Shaw, Monique Henson and Mark Purver
Segment Voice:Tess Jaffe
Website:Sally Cooper and Stuart Lowe
Producer:Sally Cooper
Cover art:Cartoon depiction of the Voyager and Pioneer spacecraft heading towards the heliopause CREDIT: NASA/JPL

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