One thing should be made abundantly clear before extolling the virtues of the Hampstead Observatory: there's no point in going there if it's cloudy.
You see, when the white fluffy things come between the stars and the telescope, you'll only be able to see a kind of fog. This will not be an interesting experience. So wait for a clear sky, and then go.
Operated by the Hampstead Scientific Society, the observatory is a rare opportunity for Londoners to get a decent view of the night (and day) sky without having to leave the capital.
This is thanks to the observatory's six-inch Cooke refracting telescope, which is a pretty darn good one according to those in the know. A smaller telescope, called the "Wildey" (after its maker, Henry Wildey), is also used by the society.
On any given visit, the observatory picks out various stars, planets and constellations of interest, with some fascinating facts and figures thrown in for good measure. It's the kind of experience which children can find inspirational, though plenty of adults will as well, of course.
Special openings of the observatory take place depending on what's going on many miles above our heads (such as a passing comet or an eclipse). Check here to find out if a meteoroid or two will be sweeping by any time soon.
Hampstead Observatory is closed for maintenance during the summer months. Be sure to check their website for up-to-date information.
During the winter it's open on Fridays and Saturdays from 8pm to 10pm, and on Sundays from 11am to 1pm.
There's no need to book, but don't forget to check that the sky is clear before leaving your home. Unless you like looking at fog.