Crescent moon joins parading planets

The waxing moon will have plenty of companions in the evening sky.

(CNN) -- The two brightest objects in the night sky will bask in the celestial spotlight on Tuesday, supported by a cast of four planets visible to the naked eye.

Shortly after sunset, the crescent moon will hover within a fraction of a degree of Venus, presenting what veteran sky watchers anticipate will be a stunning visual display.

"I've seen that myself in the past. It certainly is a striking appearance in the sky. It's unforgettable," said John McFarland of the Armagh Observatory in Northern Ireland.

The crescent moon combined with the brightest planet or a bright star has inspired the design of many flags in the Muslim world, including those of Turkey, Malaysia and Pakistan.

The waxing moon could reward observers this week for another reason as well. Because of the time of year, the dark portion of the lunar disk should glow more brightly than usual with "earthshine," or sunlight reflected off our planet.

Huddling planets

May 14 alignment of Earth, blue, with the visible planets: Mercury is depicted as purple, Venus pink, Mars red, Jupiter orange and Saturn green. Sizes are not to scale.

The Venus-moon combo is complemented by the remaining four planets visible to the naked eye, Mercury, Mars, Jupiter and Saturn.

Throughout April and May, the five planets have huddled together after sunset in western skies. Early this week, the quintet is grouped together in its tightest formation, only 33 degrees apart.

Within weeks, Mercury will gradually drop from the dance of planets, hidden by the glare of the sun, while the latter four continue moving around each other into the summer.

A close lineup of the naked-eye planets like this one happens only once every generation or so. A similar planetary grouping will not take place until 2040, according to astronomers.

To view the show, one should look low in the western sky just after sunset. A clear view to the horizon is ideal. Mercury is closest to the horizon, followed by Venus, Mars and Saturn. Jupiter appears quite a bit higher than the others.

"This alignment is a great opportunity to see the planets, since they are so easy to find in the sky," said Kevin Yau of NASA's Jet Propulsion Laboratory, Pasadena, California.