Welcome to Astronomy Cast!

Posted on Aug 30, 2006 in Astronomy | 4 comments

Astronomy Cast offers you a fact based journey through the cosmos. Each week Fraser Cain (Universe Today) and Dr. Pamela Gay (CosmoQuestX / Slacker Astronomy) take on topics ranging from the nearby planets to ubiquitous dark matter. Your questions can guide our discussion! Write us at questions@astronomycast.com and tell us what questions you want answered.


  1. Since the Big Bang, we know that the universe is expanding and we know that it’s expanding faster now than at time -1 s.
    So, here is my question. If we compare the rate of universe expansion to the speed of light, how fast is going that expansion (1%, 0.01%, 0.0001% the speed of light?) and what is its rate of acceleration ?
    If this was already been answered, please could you direct me to the right episode. If it has not been answered and is something stupid, just say so!!!

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  2. @Louis
    Hey Louis, don’t worry, there are no stupid questions in Astrophysics, only stupid answers – At least I’d like to think so, I’ve asked enough of them.
    If your question were who am I and what am I doing here? I know I’ve asked that one before and more importantly who are you and what are you doing in my bed is another one I’m sure many of us have asked.
    I know the answer to your question, I could write it here, but I’m sure Pamela Gay explains it much better than I do AND with a really sexy voice, so I highly recommend you listen to every episode from the beginning, you’ll love them.

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  3. does gravity affect sound? if so how?

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  4. @sridevi
    Looks like I’ve got my own little mini question show going on here – in this almost undiscovered area of Astronomy Cast 🙂
    Sound is not like a radio wave or a photon in that we imagine it being sucked in to a black hole.
    Sound merely propagates through a medium. It is not specifically a medium in and of itself merely the transmition of a vibration through a medium. We hear sound because of the vibration of the molecules that surround us – This could be air, or water or any number of materials.
    ‘Sound’ needs a medium to travel through. Like the apparatus of the Newton’s cradle whereby one ball bumps in to the next, which bumps in to next and so on. This is how sound it transmitted. Without a medium to travel through we would not hear any sound at all. Thus the famous strap line for a film:
    “In space no one can hear you scream…”
    Eeek! which is space would sound like ” !”
    So in a way the answer is yes – BUT only in as much as the medium that a sound wave propagates through is affected by gravity.

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