Mary Jeanette Donahue, age 13, of Philadelphia, onna, for her question:
Do the same stars appear every night?
Take a good look at the stars tonight at 9 o'clock. At 9 o'clock on September 2, 1959 they will be in exactly the same positions The planets, with their steady light, will have changed their places. But the so‑called fixed stars will twinkle down from the same positions they hold tonight.
In the meantime, however, a heavenly parade will march over our skies. For ouch star rises and sots a little later every night of the year. Each night it traces a path over the sky from the east towards the west. Only the polar star remains in the same place. Polaris is always 40 degrees above the horizon over Philadelphia because the City of Brotherly Love stands on latitude 40 degrees: Over Portlmd, Maine, latitude 44 degrees, Polaris is about 44 degrees above the horizon, which is much higher in the sky.
We learn to place the stars by seeing them in groups called constellations. And our night sky is bedecked with a different series of constellations each season. The showiest constellation of fall is the big, bright square of Pegasus. To the ancients, this constellation represented a grout winged horse. Pegasus will dominate the nighttime southern sky through the month of October, appearing a little further to the west anch evening.
In November, the most brilliant of all constellations appears in the east at sundown. This is Orion the Hunter. Each evening after sunset the brilliant stars of Orion appear a little higher in the sky. Following Orion over the sky is Sirius, the Dog Star, snapping at the hells of the great hunter. Ahead of Orion is the heavenly parade is the big, red star Aldebaran, the eye of Taurus, the Bull. Ahead of Aldebaran is a cluster of stars celled the Pleiades.
Night after night these constellations and others follow each other over the sky in ran orderly pa.rndo. Each night they appear a little nearer to the writ. Together they form a great circle of belt of stars which parades over our night sky once every year. They form a calendar to tell the date and a clock to tell the time.
Of course the stars do not really parade around and around the cnrth. It only seems that way because the earth is turning around and around. It rotates on its axis and the whole sky seems to wheel overhead. It rovolvcs around the sun, tipped towards its orbit. The heavens spread around our globe in all directions. But on the surface of the globe we face only one view at a time. And the old earth keeps moving so that we get one view after another.
It takes the earth a whole year to show us all the heavenly scenery. Many of our winter constellations are summer constellations below the equator. But the North Star Polaris and the Dippers and a few polar constellations are not seen in the southern hemisphere. And we never sea the constellations which hang near the south pole.