Week of April 30 — May 6, 2023

Springtime weather is becoming very pleasant around the Northern Hemisphere, and folks can use this opportunity to enjoy the nighttime sky.

This week, the brilliant moon will dominate our evening sky. Expect it to reach its full phase on the nights of Thursday, May 4, and Friday, May 5. On those nights, you'll see it rise over the east-southeastern landscape around sunset.

As it rises, its orange disk will likely appear quite large as it clears the horizon. Of course, the moon is no larger when it rises, but it appears that way because of some fascinating optical trickery known as the "moon illusion."

As it ascends in the eastern sky, the moon's brilliant light will obliterate from view all but the brightest of stars and will offer us an opportunity to check out some of the brighter features of the springtime evening sky.

On those nights, look above the moon for the bright star Spica — the brightest in the constellation Virgo, the maiden. Its name comes from the Latin word meaning "ear of grain," and in many depictions of the constellation, the star represents a shaft of wheat.

Spica was an important star in ancient days. Around 3200 B.C., the temple at Thebes was oriented to Spica, and in the second century B.C., Hipparchus used the star to discover the wobble of the Earth's axis known today as precession.

We now know Spica to be a blue-white star about 261 light-years from Earth; in fact, the light we see from Spica is actually the combined light from two stars that orbit one another every four days. Together, they produce about 2,200 times the luminosity of the sun.

Also above the moon — but more to the north — you'll spot a bright, yellow-orange star named Arcturus. This is the fourth brightest in all the heavens and is also the most brilliant star north of the celestial equator.

Located near Ursa Major and Ursa Minor — the Great and Little Bears — Arcturus marks the constellation Bootes, the Herdsman or Bear-Driver, though most of its stars are much too faint to see under the full moon's light.

This star's name derives from the ancient Greek word "arktouros," meaning "Bear Guard." Today we know it as a red giant star about 25 times larger and about 180 times more powerful than our sun; it's an example of what our star will become some 5 billion years from now and lies about 222 trillion miles, or 37 light-years, away.

So how do we find these two stars when the full moon does not lie nearby? Well, that's quite easy, because stargazers have long used the stars of the Big Dipper to point right to them.

On spring evenings, the Big Dipper stands on its handle in the northeastern sky not long after dark. To use it to locate these stars, simply follow the curve of the Dipper's handle outward. We say, "follow the arc to Arcturus, then speed on to Spica."

The Dipper, Arcturus and Spica will appear higher in the sky each evening for the next few months and will offer some beautiful sights throughout the summer months.

Visit Dennis Mammana at dennismammana.com. To read features by other Creators Syndicate writers and cartoonists, visit the Creators Syndicate website at www.creators.com.