Guildford Astronomical Society

Ask An Astronomer

John Evans

Do you have an Astronomy or a Guildford Astronomical Society question?

There must be more astronomical questions than there are people to ask them.  We have a plan to answer yours.  So let’s have your one, or two, or ….

We have within the Society a great deal of expertise; many members have much varied and knowledgeable backgrounds in observing, equipment and in science.  Also, if you’re new to GAS, you may like to know more about the Society’s resources and how you can access them.

John Evans FRAS has kindly agreed to be our first port of call with our questions.  John will be able to answer, or arrange to answer, almost all that that we can pass his way.  John can be contacted in person at the monthly meetings or by email on

Here follows an archive of some of the questions sent in to ‘Ask an Astronomer’ (AaA) with the Astronomer’s replies.


Click on the booklet (above) to flip through all Questions & Answers


Click on the titles (below) for individual, A4 printable Questions & Answers

Choosing a first telescopeYou’ve decided that you need a telescope but aren’t sure which one to go for. Someone wants to
buy you a telescope, for Christmas perhaps, but doesn’t know where to buy one or what to choose.
Observing the DraconidsI am interested in going out to observe the Draconid meteors at the weekend. I am completely new to astronomy and would be grateful for any practical advice you could offer on how to go about observing them. Would Newlands be a good place to observe from?
Choosing a Grab and Go Altazimuth MountWhat sort of alt az mount would you recommend as a grab and go? My HEQ6 is busy in use for imaging with my new scope which leaves my Skywatcher ED80 available for star hopping during imaging runs. Its something study, portable and basic that I am after without breaking the bank. I’ve looked online and the prices for the Sabre and the Pro Optic Ericole mounts are a bit expensive especially when you consider you also need a tripod to go with them. I’ve also been looking at the Skywatcher AZ 4 mounts. I wondered if you had any experience in this area.
Imaging Issues (A member setting up an imaging facility involving a small, short focal ratio refractor on an EQ6 mount wrote as follows)
My first problem is tracking. I am attempting to use Software Bisque's The Sky X to control my EQ6 mount. Whereas before I used the handset to do this, I am attempting to align the scope with the handset in PC Direct mode, which theoretically links it to the laptop as well. I am aligning the mount as Software Bisque suggests by aligning the alignment star with the handset then synchronising the same star in The Sky. This has turned out to be a very hit and miss affair and the star invariably drifts out of the FOV. The problem doesn't exist at Holmbury because just the handset is used, I think. Is there a better method that you can suggest?
My other problem is focusing. It's the first time that I have attempted to focus using the SXH694. In anticipation of the 'can of worms' I was going to meet I bought Focus Max, but should have got a PhD first. Again, any suggestions that will make the process just a bit easier.
Some Questions on Beginning AstronomyI came across your website whilst trying to find out more about astronomy. My 12 year old daughter is fascinated with astronomy having watched Stargazing and read a couple of books. I wanted to try going out on some clear nights this winter to look at stars and planets and wanted to get some top tips about how to set about it (binoculars, telescopes and star charts/ apps). I wonder if you have some advice or could point me to a good local retailer. Having seen your website I am interested in the talks that you have coming up and wanted to know if I can just turn up and pay the entrance fee of if I need to let someone know in advance. Would my daughter be able to attend too or are they adult only?
Can't See AnythingHelp! I have just bought a Celestron 5 but am unable to see anything.  Everything is fine in the daylight, but I can't see anything at night!
Newtonian Poor on Planets?Why does my Newtonian appear to perform well on deep sky objects but disappoint on planets?
This question also relates to the following question.
Refractors for Imaging Planets?Are refractors a good choice for imaging planets? What autoguider should I use?
This question also relates to the preceding question.
Currently Recommended Guide CamerasWhat autoguider should I use?


Image credits NASA/CXC/SAO