Landmarks are handy if you are ever lost. Believe it or not, there are still a few people not using G.P.S. They are the ones most likely to enjoy paper maps, even if they are awful to fold. If you really lost, however, a map doesn’t do much good, and you are glad when you see a familiar landmark, such as a hill or a building you know well. So it is with the night sky, except maybe we should talk about “sky marks.” Celestial navigation may not be regularly practiced by ship captains or airline pilots, but the stars remain faithful to tell us where you are just as they have for the thousands of years people have been “looking up.” Of course it has to be clear out. One summer night many years ago I was driving home through northern Wayne County, PA, a very rural area. It was after midnight. I needed to head south to Honesdale when I realized I had no idea where I was. I made a wrong turn somewhere, and there was no road sign to help me, and I wasn’t about to knock on the door at that hour to ask directions. Suddenly, I noticed the Big Dipper. I was driving right for it. Knowing the constellations, I at once knew I was heading due north-for how long I did not know! I was headed north toward New York State! I turned the car around and headed south- towards Sagittarius and the Milky Way Band. I kept my celestial course till I came upon a landmark- a church in Pleasant Mount! From there I knew the roads home. I think if someone gave me a G.P.S. I’d still want to use the friendly stars. Moral: NEVER get lost on a cloudy night (unless you have a G.P.S.). Sometimes when surveying the Universe from my deck, spanning millions of light years with a sweep of my eyes alone or binoculars, or taking a closer sweep at the eyepiece of my telescope, I imagine the astonishing size of the Galaxy- well beyond anything we can find a way to relate. Suppose that very dim star we might pick out was actually the Sun? With my imagination I think of some future space explorer venturing deep into interstellar space. If such a traveler became lost in space, and spacecraft guidance systems failed, could he or she navigate by the stars to get home? Suppose you didn’t know which of those millions of faint specks was the Sun? Forget the constellations; far from our solar system you would not find them at all- except perhaps if you are looking back in the direction of our Sun, and a star pattern- say Orion- was receding in the stellar background. Hopefully you could start by looking for the more distant “sky marks” to narrow down where you are in the Galaxy. Look for the hazy Milky Way Band and see if it matched at all what you knew from Earth. Then look for more distant galaxies like the Andromeda Galaxy. See where it is in relation to the Milky Way Band. You could also use a radio telescope to detect emissions from far-distant, known quasars and other cosmic radio emitters, to triangulate where you are. With a spectroscope you could start searching for yellowish, class G-2 stars, one of which is our Sun. Such an imaginative exercise helps us appreciate the wonder and immensity of it all. Thankfully, in our day dream (night dream?), we come back home to Earth, to our deck or our easy chair and realize we’re still on our faithful planet. We weren’t lost at all, but found among friends, our fellow Earth travelers who call this home. Full Moon is on Sept. 29 and is the “Harvest Moon,” the full Moon closest to Fall Equinox. Send your notes to email@example.com and please say where you read this column. Keep looking up!