In the show this time, Dr David Floyd tells us about quasar microlensing and we talk to Dr Tim O'Brien about his role at Jodrell Bank in the first JodBite. As always, your questions are answered by Dr Iain McDonald and we round up some odds and ends from the world of astronomy.
JodBite with Dr Tim O'Brien
In this first JodBite, Dr Tim O'Brien discusses his role at Jodrell Bank, including his research into classical and recurrent nova explosions, supernovae and planetary nebulae. Tim also talks about his public engagement activities including the BBC show Stargazing Live, and some unique events like Live from Jodrell Bank, a rock festival in the shadow of the Lovell telescope.
Interview with Dr David Floyd
Dr. David Floyd (Monash University, Australia) talks to Leo and Mark about quasar microlensing. He describes what a quasar is and why their central engines, massive black holes surrounded by disks of very hot matter, are interesting. He also explains how gravitational microlensing allows us to use the stars in foreground galaxies to probe the centres of distant quasars and understand the black holes that power them.
Ask an Astronomer
Dr Iain McDonald answers your astronomical questions:
- The first question comes from Jude Austin, who asks: "If you stood on the surface of Mercury during the day, could you see the stars or would the Sun's brightness make this impossible?"
- On the forum, Gweilo says: "On average, each planet is 1.8 times further from the Sun than its predecessor - why?"
Iain refers to Bode's Law in his answer.
- Frances Day says: "I just saw a NASA video about the new findings from Voyager of what happens where the Solar wind hits the interstellar medium. I'm puzzled about why there is a shockwave."
Iain refers to the heliosphere in his explanation.
- Our final question comes from Peter Ellinger: "Dark energy is the name given to the phenomenon causing the expansion of the Universe. The following train of thought comes to mind: if E=mc2, then, as a star shines, the mass of the Universe decreases, so gravity decreases, so the Universe would expand faster. Do the sums add up? If not, where am I going wrong?"
Iain explains that gravity doesn't decrease when mass is converted to energy because all energy exerts gravity.
Odds and Ends
It has been reported that a former astronaut (Mae Jemison) has been appointed as head of the 100 Year Starship project. This is a project aimed at paving the way for technologies to be developed that would be required for a mission to another star system in 100 years time.
The RadioAstron 10 metre space radio telescope was used for the first time in November 2011 as part of an
Globe At Night is a public participation research project aimed at measuring how the night sky around the planet has changed over the past six years. You can, at the time of release, take part in the current survey here.
|JodBite:||Dr. Tim O'Brien and Libby Jones|
|Interview:||Dr David Floyd, Leo Huckvale and Mark Purver|
|Ask An Astronomer:||Dr Iain McDonald|
|Presenters:||Stuart Harper, Leo Huckvale, Libby Jones and Christina Smith|
|Editors:||Jen Gupta, George Bendo, Mark Purver and Christina Smith|
|Segment Voice:||Mike Peel|
|Website:||Christina Smith and Stuart Lowe|
|Cover art:||Comet Lovejoy just before Dawn. CREDIT: lrargerich (flickr)|