Let the moon guide your eye to the star Spica and planet Saturn on May 21.

The waxing gibbous moon glides close to the the star Spica this evening, on May 21, and pairs up with the planet Saturn tomorrow, on May 22. The moon will pass relatively close to Spica and Saturn for the next several days, as the moon moves in its endless orbit around Earth.

The star Spica and the planet Saturn appear in the southeast at nightfall, and then move westward across the sky during the night.

Although you’ll always find the star Spica in the same place in the sky on May evenings every year, Saturn’s proximity to Spica is special to this year. At present, Saturn shines in front of the constellation Virgo, just west of the Libra/Virgo border. On this date in 2014, Saturn will in the middle of the constellation Libra.

Yesterday we talked about learning to “follow the arc” to the star Arcturus in the constellation Bootes. You just follow the curve in the Big Dipper’s handle until you see this orange star.

Tonight, let the Big Dipper introduce you to another bright star. This star is Spica in the constellation Virgo the Maiden. You can follow the arc to Arcturus AND drive a spike or, as some say, speed on to Spica.

Now is the perfect time to look outside in the evening and learn a phrase useful to sky watchers. The phrase is: follow the arc to Arcturus.

First locate the Big Dipper asterism in the northeastern sky. Then draw an imaginary line following the curve in the Dipper’s handle until you come to a bright orange star. This star is Arcturus in the constellation Bootes, known in skylore as the bear guard.

The star Deneb – visible by mid-evening every May – is one of the most distant of the bright stars. When you gaze at this star, you are gazing across a great distance of space. The exact distance to Deneb is not known for certain, with estimates ranging from about 1,425 light-years to perhaps as much as 7,000 light-years.

As soon as darkness falls on May 17, 2013, look for the moon – at first quarter phase today – close to a bright star, Regulus. Sparkling blue-white Regulus is the brightest star in the constellation Leo the Lion. It represents the the Lion’s beating heart. You can also see some planets tonight, and every night in May. Jupiter and Venus are now in the west after sunset, heading for an exciting planetary trio with Mercury later this month. The moon is now sweeping across the evening sky from night to night, heading for the star Spica and then the ringed planet Saturn later this month.

The ecliptic is the plane of Earth's orbit around the sun. As Earth moves, we see the sun travel a narrow pathway in front of the stars. The ecliptic defines that pathway, which we most often call the Zodiac.

The Zodiac is the narrow band of stars circling through the heavens and running on both sides of the ecliptic. It’s marked by the sun’s path across our sky, because officially the ecliptic the is the plane of Earth’s orbit around the sun. The moon orbits on nearly this same plane. So as the moon makes its monthly rounds – orbiting again and again around Earth – it moves in front of the constellations of the Zodiac, passing the same stars and constellations again and again. Tonight – May 16, 2013 – the waxing crescent moon shines in front of the faint constellation Cancer.

Here is the star Vega, the fifth brightest star in the sky. You’ll find this beautiful bluish star by looking northeastward in mid-evening. It’s so bright that you can notice it, even when no other stars are visible.

Here is the star Vega, the fifth brightest star in the sky. If you’re in the Northern Hemisphere, you’ll find this beautiful bluish star by looking northeastward in mid-evening. It’s so bright that you can notice it, even when no other stars are visible. Because it is the brightest in the constellation Lyra the Harp, Vega is sometimes called the Harp Star.

On the evening of May 14, 2013, the waxing crescent moon shines close to Castor and Pollux, the two brightest stars in the constellation Gemini the Twins. On the opposite side of the moon is even a brighter star, Procyon. By the way, an imaginary line drawn from Procyon and right in between the Gemini stars takes you to Polaris, the North Star. It’s a very long jump across the heavens but the imaginary line will take you there. Try it tonight!