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Excellent suggestion. To which I'll add Newgrange (or the whole Brú na Bóinne site). A fascinating visit including a guided tour of the Neolithic monuments. When we were there, English Heritage members got free or reduced entry (can't remember which).

Skywatcher are certainly putting out some interesting new products.

Personally, I would be looking for a longer focal length EP rather than a shorter one. Under dark skies, a wide field eyepiece can give lovely punchy images; over-magnification is a real risk if you use a too short eyepiece, and a wider field of view can give you the pleasure of seeing things in relation to each other. I think you have a Heritage 150 - which is an f5 scope. A general rule of thumb is that most of the time you won't get excellent views with an eyepiece shorter than your f ratio - so although a 5mm eyepiece might be useful - a 2x barlow and the 10mm is likely to give you as good a view as an affordable 5mm EP. An alternative to a 2x Barlow is a cheap zoom lens - the SVbony 7-21mm is nice and light, and has a decent range - a relatively narrow view at 21mm, but nice images as the power increases. That and a 32mm Plossl would be my suggestion - of course, other people would have other suggestions. ETA - oh, and M31 is amazing in its ability to underwhelm. It is so broad, and relatively featureless so it just looks like a misty smear in most cases (overall, what you see in photographs is 6x the diameter of the moon, so you only get the central bulge in the eyepiece view, and that's fairly featureless unless you're under a very dark sky when you might be able to make out the hint of some lanes)

One thing to remember is that in the Summer months, the further north you go, the shorter the astronomical darkness (and for much of the UK you get; none at all between June and July) so Cornwall will be better than Kielder. If you can travel later in the year, there's a stunning campsite on the top end of Loch Morlich, below Cairngorm summit. The campsite has low level illumination, but you can walk through some woods onto the beach by the loch and it's as dark as I've seen in UK,

Fforest Fields near Brecon has a very good reputation - particularly what they call 'the upper field'. I've not been myself, but I think I read there are electric hookups there as well. https://www.fforestfields.co.uk/campsite-wales

I would say that launch is probably adequately insured and won't be an issue; however, to me it feels that deployment is the issue - and they're definitely uninsured risks.

Oh good to know the launch has beenput back - we'll nip out to the shops now

As well as the problem with the Dobsonian not being a tracking mount, it is very likely that you can't get the image to focus directly onto the dSLR sesnsor as the focuser doesn't rack far in enough.

Excellent choices there TC - one of my favourites is The Curious Cases of Rutherford and Fry - particularly the Podcast version where you get extra chat between the two. Their chemistry is just great.

I think it's fair to say that there isn't a single formulation of MOND that hasn't been ruled out for one reason or another. There may be new formulations that haven't been tested yet. As I recall, even Milgrom accepts that MOND requires some form of DM to make things work.

Consider you're a goalkeeper standing on your goal line, and the other team's goalie is holding up a 6x4 photo. That's the area of the sky that the XDF image covers.

Those papers discuss long term cumulative damage to the lens and cornea, and it is true that UV does cause damage, but the question in this thread is about the dangers (or otherwise) of observing, where an image is formed at the retina. Just like using a magnifying glass to start a fire, it's the IR light that causes the heating that causes the damage to the retina.

The radio telescope at Nançay (in the Cher Department of central France) is an interesting visit - firstly, as a different way of having a radio telescope - but it also has a good visitor centre. In terms of the Michelin Green Guide, not necessarily "worth a journey", but worth a detour - it's a good two or three hours. https://en.wikipedia.org/wiki/Nançay_Radio_Observatory

Jodrell Bank Discovery Centre is local to us. Smithsonian Air and Space Museum in DC and the Udvar Hazy Centre out by Washington-Dulles International Airport. The Armstrong Air and Space Museum at Wapakoneta, Ohio ( a surprisingly good selection of items and books in the shop)

A friend was observing one of the Galilean moons and saw it emerge from behind Jupiter, move away from the planet and then disappear again as it moved into Jupiter's shadow. This was possible because Jupiter was some way off opposition, so the shadow went off at a fair angle.

I can't see that it would affect your focal length, but it will increase your focal ratio (in that it will reduce your aperture by about 1cm - I reckon about 0.5cm at each edge)

There isn't really a direct measure you can apply - it more comes down to the size of the field of view. However, it is reasonable to say that when used for Prime Focus AP, the image captured by a camera is roughly equivalent to that seen in an eyepiece equivalent to the diagonal size of the sensor. So an APS C sensor captures what you might see with a 30mm focal length eyepiece. What magnification that represents depends on the focal length of your Scope. A webcam with a 3x4mm sensor would be equivalent to a 5mm eyepiece - so therefore more suited to planetary imaging. It's a rough and ready measure, but works to explain the principle

The height of a transit is always the same (except for solar system objects), so what's probably of interest is to know when they're due south at a good time for observing. I'd suggest a classic planisphere as the best way to see this.

As I understand it, there is some suggestion that although Dark Matter doesn't interact with 'normal' matter (except gravitationally), it may well interact with itself. The reason that this is suspected seems to relate to the way that the distribution of Dark Matter in the very central parts of a galaxy is slightly different to what would be expected if there were no interactions at all. It thus seems possible (to me at least) that this may represent a new force altogether to go along with the Electromagnetic, Strong and Weak forces, with a new boson as well to mediate the force. It's exciting of course, but tricky to see how it would be possible to run experiments that would let us find out more.

Good to hear.

Oh dear!

Hi Richard, and welcome to the fellowship of amateurs. You're probably aware that your local club is Macc Astro - a very well established club - and when the current virulence is over, they are likely to restart their regular trips to Anglesey for some better 'dark sky' observing. Neighbours with motion sensitive lights are a regular pain - if you know them well enough to ask them to move them to a better angle, that's really useful. There should be a law against lights going higher than any walls, fences or hedges. Keep an eye out for details of the Online "North West Astronomy Festival" which is scheduled for 25th September - and it is hoped that they'll be able to meet up for a 'Real Life' weekend of Astronomy in 2022 (probably near Warrington). Great to have you with us - Owen (from the Mid Cheshire AG)

It's probably not possible to make a valid assessment on the scale and spread of the impacts on the basis of their current visual appearance, when you consider that the age of Aristachus is approximately four times that of Tycho - therefore there has been four times the darkening of any ejecta. Another consideration is that Tycho is over twice the diameter of Aristarchus and 70% deeper, so it represents at least 7x the volume of material displaced.

You might want to run an anti-malware checker on your phone, as it looks as though you were subject to a redirect - and I'm not absolutely convinced that you can be sure of apks that come from Aptoide rather than direct from SkyWatcher. I would suggest you uninstall the app from your phone - then get a download direct from https://inter-static.skywatcher.com/downloads/synscanapp_1190_store.apk or if you want the 'pro' version https://inter-static.skywatcher.com/downloads/synscanpro_1190_store.apk (if necessary download to a laptop/PC and then copy it to your phone by USB/Bluetooth) Hopefully, all will be OK - but I do wonder why you were redirected and why you were required to give permissions over and above what you would expect. It would also be worth checking if Aptoides has installed its own app and permissions - get rid of them as well if you're not sure about them Edit to add: Aptoides says that a green tick next to a package should indicate that it's safe. That may be reassuring. Up to you.

I'm not sure what 'effect' you're trying to explain, and why you don't think that the usual explanation of heating due to atmospheric compression doesn't cover it.