September 2015 Extra: Rewound

In the show this time, Dr Rainer Beck explains the complexities of studying galactic magnetic fields, Hannah Stacey talks to us about strong gravitational lensing, and your astronomical questions are answered by Dr Joe Zuntz in Ask an Astronomer.

JodBite with Hannah Stacey

Hannah Stacey talks to us about her year as a Masters student at JBCA. When not presenting the Jodcast, Hannah tries to make sense of the quasar population. She explains how gravitational lensing can be used to observe and magnify objects in the distant universe and how she uses gravity as a magnifying glass to trace activity in quasars. She describes the tools of her trade (eMerlin) and the principles behind multi-dish radio observations and gives us an overview of her results and what they tell us about these distant powerhouses.

Interview with Dr Rainer Beck

Dr Rainer Beck works at the Max Planck Institute for Radio Astronomy where he researches cosmic magnetic fields. He tells us how we can use radio polarisation to observe magnetic fields in galaxies their relation to star formation. We find out how we can use background quasars to measure foreground fields and why the Square Kilometre Array will tell us when magnetism appeared in the Universe.

Ask an Astronomer

Dr Joe Zuntz answers your astronomical questions:

• Phillip asks, "Is there such a thing as dark radiation?"
• Ike asks about the rules for interacting photons
• Robert says: "How does special relativity affect measurements of the Sun's mass?"

Odds and Ends

The Cassini imaging team have measured the libration of Enceladus and determined that a large ocean lurks beneath its surface. The existence of a subsurface sea beneath the south pole was already known due the ejection of water plumes from southern crustal fractures but the size of this sea was not well constrained. By 'locking on' to particular surface features, such as craters, and measuring the wobble of the moon due to tidal interactions with Saturn, the team were able to indirectly probe the interior of the moon. They found the extent of the wobbling, or libration, is not consistent with a body whose crust is rigidly coupled to the core and instead, the surface appears to be hiding an ocean that completely envelops the moon's core. Cassini will flyby Enceladus on October 30th while the plumes are at their most active and will attempt to carefully measure the composition of its watery output. For more information, read the press release here and the paper here.

Jet Propulsion Laboratory recently gave an update on a new class of rovers that they are designing in collabroation with Standford University and the Massachusetts Institute of Technology. The rovers, called hedgehog robots, are cubes with spikes that are designed to roll using internal flywheels rather than using wheels. This design is particularly useful for roving around a low gravity environment such as a comet or asteroid where a traditional rover with wheels may bounce off of the surface or flip easily. More details, including videos, are provided in the JPL press release or the Space.com news article on the rovers.

Nasa's "Year in Space" mission is halfway through and to mark this occasion they have released some interesting facts about what will happen to astronaut Scott Kelly's body while he spends a year on the ISS. Read about it here. In other news from space, a team of scientists have performed experiments to determine whether whiskey aged in space tastes different to whiskey aged on earth. Find out more here.

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