Palomar Observatory Trail is a 4.5 mile out and back that connects the 1928 observatory with Observatory Campground. Palomar Observatory is owned and operated by Caltech and is currently closed to the public due to the pandemic. I guess they want to conduct their “compelling scientific investigations in astronomy and astrophysics” in private. Since you can’t park in the observatory parking lot (or anywhere close by) the only option is starting at Observatory Campground. Observatory Campground is owned and operated by the Cleveland National Forest and is also closed. You can, however, park on the side of the road and walk through the campground to the trailhead. The trail starts at 5,000 feet elevation and is shaded by beautifully overgrown oaks, cedars, pines and firs. Surrounded by acorns, pinecones, blue jays and lizards, it is the perfect hike for a two year old (even if the parents are the only ones doing the hiking).