|Help and Advice|
|Transit of Mercury 2016|
|Giving long exposures on a digital camera|
|Photographing star trails|
|Predicting the ISS and other satellites|
|Using a mirror to view a partial eclipse|
|Simple Guide to Viewing the Space Station|
|Choosing a Telescope|
|Tips when projecting the Sun|
|Starting to Use Your Telescope|
|Imaging with a DSLR through the telescope|
|Buying a telescope for a child|
|Photographing a partial eclipse|
The January 2008 Popular Astronomy carries a project in which you mark a balloon with galaxies, then blow up the balloon so that the galaxies expand away from each other, just as in the expanding Universe. It poses some questions at the end – and if you've come here, you probably want to know more.
So here are ten top questions about the expanding Universe, answered for us by Dr Francisco Diego of University College, London.
Q How do we know the Universe is expanding?
Q How loud was the Big Bang?
A Although TV documentaries like to have a sound to it, and show it from outside, there was no air surrounding it so there couldn't have been any sound, and there was nothing outside it so no-one could have seen it happen. In space, no-one can hear you scream, remember?!
Now the answers to the questions in the Very Challenging part of the project:
Q Think about how you can use your answers to work out the age of your balloon Universe. How do you think the results would change if you used a different galaxy to measure from?
A The age of the Universe was measured directly during the experiment – the time you took to blow up the balloon. But if you were on a galaxy and saw the others moving away from you at a given rate, you could work out how long it had been since all the galaxies were next to each other. It would not matter which galaxy you chose, anywhere on the balloon – the rate of expansion is the same for all.