A pair of binoculars is a great way to get started in astronomy, birding, and just as an addition to your hiking kit.
For Astronomy, choose binoculars that have a lower magnification so you can more easily keep your view steady. Binoculars with a 40mm - 60mm aperture are good for hand-held use. Anything larger and heavier will really require a tripod to hold steady.
If you wear glasses, pay attention to the eye relief, and look for 14mm or better to use with your glasses. Longer eye relief is generally found on mid to higher end binoculars. As you step up in price and quality, also look for waterproof and fog proof lenses. You'll pay a bit more for these models, but it will be well worth the investment on a humid night.