First time viewing the moon ...

[Priya]

I have a Celestron Nexstar 4SE and I finally managed to get the finders scope aligned to check out the moon. I know that the moon rotates around the Earth but I was astonished at how quickly the moon moved across my viewfinder! Does the moon really move that quickly across the viewfinder while you are observing it?

I thought I would check here if this was normal or if there was some technical aspect to the telescope itself that I was not aware of.

Many thanks for any help / guidance.

[emadmoussa]

Doesn't your scope have auto tracking? And yes, the moon moves out of the field of view very quickly...depends on the scope / eyepiece field of view and magnification. Schmidt Cassegrain telescopes like yours (If I understand correctly) have smaller field of view than refractors or even reflectors for this matter.

[D4N]

Objects on the ecliptic will appear to move at 15 arc minutes per minute of time.

The moon varies between 29 and 34 arc minutes diameter so it will take about two minutes to go from looking at one side to looking at the other (not accounting for its orbital motion as it is insignificant on this time scale). The sun is about 32 arc minutes so the same applies.

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[Priya]

Wow, pretty amazing! Thank you for the explanation.

@emadmoussa yes it does have auto tracking, haven't had a chance to test it out yet.

[lbscherm]

Great explanation D4N! Thanks from a fellow newb

[Algieba]

I was very surprised the first time I used a telescope how quickly everything moves across the sky and having to find the objects again was quite difficult. I heard auto tracking is good, but I've never used it myself.

[Antuntus]

Could you explain a bit more about auto tracking pls?

[D4N]

Could you explain a bit more about auto tracking pls?

It is when the mount has a motor that counteracts the rotation of the Earth to keep the target within your field of view.

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[Antuntus]

I thought it was something like that.  Sounds quite expensive?

[D4N]

Depends on what you already have, some mounts can be retrofitted with a cheap RA motor which is quite fine for visual observing.

Mounts designed for astro photography however often cost far more than the telescope that's on them.

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[Antuntus]

Thanks for explanation. Far away for me still