May is erupting all around us, and the transition now underway in the night sky is as thrilling as the warm-weather changes under our noses.
Indeed, spring is a wonderful time of year on Earth’s Northern Hemisphere where the lifeless winter landscape is bursting alive with color, texture and sound.
But in the skies of the wonderful month of May, the brilliant stars of well-known constellations of winter are saying goodbye, while the new, somewhat dim and undistinguished constellations of spring are taking over.
Daylight is handed off to dusk and then twilight around 8 pm before darkness set in. The pinks and salmons yield to the indigo, purple and the deepest blue this side of black. It’s fun to play the “color game,” each person picking out a shade from the sky pallet—everyone nodding when seeing tangerine in the twilight. Less than 30 minutes after you start naming the colors of sunset, sky is filled with stars, game over.
The first star to come out and make a wish upon is not a star, it’s the planet Venus. Just face west while watching the twilight color show and scan your eyes upward, and shazaam!
Venus is so bright that it dazzles our optical senses—only the Sun and Moon are brighter (-4 magnitude for Venus; -14 for the Full Moon; -27 for the Sun in the logarithmic scale of magnitude.)
The second planet from the Sun will take 2 hours to drop to the horizon, the wild shimmering of white light is tinted with colors as it refracts through 100 miles of Earth’s atmosphere.
So dramatically bright is the light reflected off Venus’ clouds that it is often mistaken for a plane landing light, a mountain beacon or even a UFO. In fact, under ideal conditions you may see a shadow cast on the ground by the Venusian light. You need to be away from city light, but it is possible for a broom handle to cast a shadow on a white surface from the light of Venus 30 million miles away.
In the twilight to the east it is much darker and your eye catches the brightest star of our heavens, Sirius. Still hugging the southern horizon and blazing at a magnitude of -1.5, the main star of the Big Dog, Canis Major. Once dominating the winter sky, this famous “Dog Star” of Egyptian history will be gone from the night an hour after sunset.
Gone are the constellations of Taurus the Bull and Orion the Hunter. But the twin stars of Gemini, Castor and Pollux, are still hanging in there with Venus converging on them all month.
Directly overhead at dark is bright star Regulus in Leo the Lion. And the zodiacal constellation roars from its lair directly overhead, called zenith.
The front of the lion has a mane of stars shaped like a backward question mark dotted by Regulus, the “Regal Star” of antiquity. All five naked eye planets visit this star and constellation in the Zodiac, a place for royalty in many cultures’ mythology.
Looking to the northeast, the Big Dipper asterism of the constellation Ursa Major is pouring its celestial contents on the landscape.
Follow the curve of the Big Dipper’s handle and you’ll see the two brightest stars of the spring nights. The old astronomy axiom is “From the Big Dipper’s handle, arc to Arcturus and speed on to Spica.”
Arcturus is the third brightest star in all the sky, and anchors the bottom of the kite-shaped star pattern named after a herdsman called Bootes (pronounced BOO-oh-tez).
A super-giant star nearly 30-times larger than our Sun, Arcturus is 36 Light Years away, its red-orange light distinctive to the human eye catching those photons across the Universe.
After using the handle of the Big Dipper to “arc to Arcturus,” continue to “speed on to Spica,” and its blue-white light that left this star 260 years ago and reaching Earth in your backyard tonight.
Spica, meaning “sheath of wheat” to ancient Greeks, is all alone among the faint, sprawling stars of Virgo the Virgin that take up most of the southeast until midnight. Virgo ranks second in size to constellation Hydra the Water Snake, slithering below the young maiden along the southern horizon from east to west.
Those two constellations take up more than 12 per cent of the Northern Hemisphere of stars. Add the third largest constellation, Ursa Major the Big Bear at another 6 degrees of sky coverage and these three star patterns make up nearly one-fifth of the spring night sky!
The Big Dipper is a star “asterism,” being just a part of the larger constellation the Big Bear. The famous seven stars are the he rear-end and long tail of the bear—though no species of bear has been discovered with such a long tail. The bear is on his back this time of year, the two stars of the outside bowl pointing to the North Star, Polaris.
The spring skies have nice surprise for stargazers. The fourth brightest object in celestial canopy—planet Jupiter—rises at sunset and takes command of the eastern horizon by 10 pm.
That is Jupiter that is so brilliant in the east and attracts the eyes of hoot owls and night owls looking skyward.
Shining at a magnitude of -2.5, Jupiter never gets a bright as Venus, but it is impressive nonetheless. Put a telescope on the fifth planet and you will not only see the disk of the planet, but the tiny star points of the four moons discovered by Galileo nearly 400 years ago. Even with binoculars held steady you can see a hint of Jupiter’s disk and tiny stars around it.
Jupiter will be around all spring in the small and faint Zodiac constellation Libra the Scales, the only inanimate object of the Zodiac. And right behind Jupiter rising after midnight is planet Saturn, and Mars even later—all to be major players in the sky during the summer.
The spring skies in the month of May have reached a point of no return for the cold weather stars of winter. And that’s a refreshing change.