Meteor Shower: The main event for tonight is definitely the Perseid meteor shower. The shower peaks on August 12, but the maximum is broad so by scheduling on August 11 we give the local clouds two chances to allow us to see something. Meteor showers occur when the Earth's orbit takes us through the debris trail left by a comet. Dust particles left by the comet collide with our atmosphere at high speed, heating them so they glow and produce the wonderful firework we call "shooting stars". This year's Perseid shower will be dimmed by a gibbous Moon making dimmer meteors harder to see, but we hope for a good show. Meteors are best observed without any instruments, looking up for a long time will increase your chances of seeing them. So bring a lawn chair or blanket to sit on, comfortable clothes, water and a snack.
Solar System: While we wait for meteors, we will set up a telescope to look at Jupiter. On August 14 the giant planet will be in opposition, which means it will be as bright and as near to Earth as it will be this year - in fact it will be at its brightest since the century began. If the night is reasonably clear we can expect a good view of the bands of clouds on the planet as well as of some of its four large "Galilean" moons. Jupiter is clearly visible in the Eastern sky these days as an unusually bright "star." Neptune is also visible, we may try to view it as well, but this fainter, more distant planet is best viewed under conditions better than we are likely to have in mid August.
Stars and Clusters: Several beautiful globular clusters will be visible, most famous among them the Hercules cluster (M13). This tightly bound collection of some 400,000 stars in a sphere only 140 lightyears across, is about 25,000 lightyears from Earth. Globular clusters contain the oldest stars in the galaxy. They inhabit a sphere about the galaxy's center; tonight the center will be relatively high in our sky, so we will have an opportunity to see many of the globular clusters that surround it. We will also have the opportunity to see some nice open clusters, my personal favorite likely being the Wild Duck cluster (M11). Less tightly bound, open clusters of hundreds (in this case 3000) stars produce beautiful telescope images. Several other clusters will be available. We may look at a nice binary star such as Albireo, the head of Cygnus the swan.
Nebulae: One of the most beautiful telescope objects in the sky, the Ring Nebula (M57) will be right overhead and we will surely take a look at this pretty remnant of a Sun-sized star that died within the last 30,000 years some 2300 light years away.
Galaxies: Not a great night for galaxies, but we may look for the Whirlpool Galaxy (M51) or other nearby galaxies if the sky is particularly dark.