You could call this the most sophisticated stargazing event in town. On the third Thursday of every month, the Harvard-Smithsonian Center for Astrophysics opens its doors to the public for an amazing star-filled night.

Here is what happens during these "Observatory Nights", as Harvard calls them: the evening starts with a lecture from one of the Smithsonian's astrophysicists, on a new topic every month. While each lecture has scientific value, the tone is largely entertaining, with videos, pictures and good humor combining to make this first hour or so surprisingly engaging. When the lecture is over, and weather permitting, the real deal starts: the public follows the astrophysicists through the Smithsonian's building and climbs on to the roof. There, several telescopes are pointed to the stars and planets most visible on that evening.

This outdoor experience is unlike any other: on warm summer nights, the mood is that of a camp bonfire, and you will feel like kids watching a firework; on clear winter nights, silhouettes bundled in several layers of clothing patiently wait their turn to peer into the universe. In addition to being an opportunity, rare nowadays, to spend the night outside, Observatory Nights are probably the only way to really see planets and stars in their splendor, as the Smithsonian's telescopes are way beyond the reach of most amateurs - after all, this is probably the only place around where you can walk INSIDE a telescope. For most visitors, this will be the first time in their life that they will see Saturn's rings or Jupiter's satellites with their own eyes.

The format is quite flexible: you may stay on and question the Smithsonian's scientists for hours under the starry canopy, or leave as you wish after you have had your turn at the instruments. In any case, you are unlikely to regret this feeling of being thrust into the sky, with the Boston - and the rest of the world - at your feet.

As you would expect, children are welcome; in fact, they may find both the lecture and the stargazing unforgettable experiences.