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February 2010 Extra: Stormwatch

February 2010 Extra

Stormy. In this show we talk to Jim Wild and Marek Kukula about the Sun. We put your astronomical questions to Tim, and round-up your feedback.

Interviews

Stuart went to Astrofest at the beginning of February. While there, he found the time to talk to Dr Jim Wild (University of Lancaster) about changes in the space environment, often known as "space weather", and the role that the Sun plays in this. He also caught up with Dr Marek Kukula (Royal Observatory Greenwich) to find out about Solar Season at Greenwich and a new Galaxy Zoo style project Solar Stormwatch.

Ask an Astronomer

Tim answers your questions:

Joe writes in to say "I've seen, as I'm sure most people have, pictures of our Galaxy. I've also seen pictures of the spiral arm where the Earth sits, usually with a circle superimposed and some text which states confidently 'you are here'. My question is, how can this be? Who or what has been far enough out to take these photographs? If these pictures are an approximation, or best guess to the structure of our Galaxy then, again, how do we know what our Galaxy should look like without being thousands of light years away from it to see?"

The 2MASS (2-Micron All-Sky Survey) near-infrared image of the whole sky.

An edge-on disc galaxy: NGC 4565.

A recent artist's impression of the structure of our Galaxy based on Spitzer Space Telescope data.

For a historical background there is the 1920 Shapley-Curtis great debate on the scale of the Universe and the 1918 paper by Harlow Shapley on the distribution of globular clusters in the Milky Way. There is a much more up-to-date paper by Gillessen et al (2009) on the distance to the black hole at the centre of the Milky Way.

Tim also mentioned a recent BBC video in which he answers the question "What is a lightyear?".

The Gaia space mission.

Odds and Ends

The increase in solar activity could spell trouble for global positioning systems. Solar flares can overwhelm the weak signal sent by GPS satellites - a problem that might have been overlooked when sat nav technology was developed.

A strange comet-like object in the asteroid belt has been imaged by the Hubble Space Telescope. The image reveals an "X" structure near the brighest end and is baffling astronomers as to how it could have formed. Possible explanations include that is it a comet in the asteroid belt or that is it the result of a collision between two asteroids.

Podcast updates: The Jodcast is now featured on Astronomy.FM. Two Jodcast listeners, RapidEye and Rob Bowman have recently contributed episodes to the 365 Days of Astronomy podcast. And finally, Megan's Doctor Who story explaining a Nature paper that she co-authored has been given the audio treatment by Darker Projects with the Jodcast's Dave as The Doctor.

Show Credits

Interview:Dr Jim Wild and Stuart Lowe
Interview:Dr Marek Kukula and Stuart Lowe
Ask An Astronomer:Dr Tim O'Brien
Presenters:Adam Avison and Jen Gupta
Editors:Adam Avison and Stuart Lowe
Segment voice:Kerry Hebden
Website:Stuart Lowe
Cover art:The northern lights Credit: Jökull Másson

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