May a marvelous month for planet-watching

Turn the month of May into a planet-watching extravaganza! OK, maybe I'm a little too excited about this, but for those readers who for the first time in their lives are taking an interest in the skies and enjoy watching them change before their eyes, the merry month of May is like Planetary Movements 101.

Only half of the planets are seriously contending for your attention, but they make the most of their other-worldly personalities.

Mercury, Venus and Saturn will be vying for your interest in the western skies after sunset. Jupiter will strut down the cosmic catwalk later on in the southeastern skies.

Alas, mighty Jupiter doesn't rise until about 11 p.m. at the beginning of the month. But as we catch up with it in our orbit, it will rise earlier and earlier. By the end of the month, the great king will rise around 9 p.m. You cannot mistake it; it is by far the brightest object in the southeast at those hours.

Even though it shines very brightly, being down so low to the warm horizon ruins attempts to see the fine details of the giant of the solar system. Summer will be a better time to see Jupiter; it will be rising earlier and soaring higher at more reasonable hours.

This is a great month to see Saturn, especially if you have a telescope to help discern those beautiful rings. The ringed planet is high in the southern skies at the beginning of May, but will seem to creep up slowly on Venus in the west as the month wears on. Our orbit will soon take us to the other side of the sun as Saturn, the belted beauty, will bow out of the planet play, behind our star, but only for a while.

If you have been one of the followers of Venus, you will have already noticed that the brilliant jewel of the western skies keeps rising ever so slowly above the horizon. It has been running around the sun, trying to lap us in its orbit. It will succeed soon, and will get brighter as it comes nearer to us. Being covered in clouds that reflect about 60 percent of the sun's light makes it one really dazzlingly bright planet.

As it gets nearer, it is also easier to see details through a telescope. At the beginning of the month, see how Venus is like a miniature gibbous moon. As it closes in, it will look more and more like a first-quarter moon, with half of the planet clothed in darkness.

Please mark May 19 on your calendars! It is on that evening that the crescent moon and Venus nearly kiss. It will be awe-inspiring, a great evening to write a poem.

These phases of Venus were first seen by Galileo and proved -- to him anyway -- that Venus was orbiting the sun and not us, an idea that centuries ago was a revolutionary paradigm shift. It took decades after his discovery for that new idea to be generally accepted.

Venus will peak during the month, almost seeming to hover there in position. In June, it will begin to slowly sink toward the horizon as it passes between the sun and us.

Mercury is, at the moment, rounding the sun on the far side. And true to form, the mercurial little one will leap up into the western skies around midmonth, seemingly out of nowhere.

By the end of the month, it will have already reached its peak in the heavens after sunset, just about a hand span above the horizon, only to quickly disappear during June.

You'll notice Jupiter and Saturn will hardly move at all through the skies during their May appearance. They are part of the very distant outer planet group, all very slow-moving, in no hurry to get anywhere. They will be in about the same area of the sky the next time we swing around.

Venus and Mercury are inferior planets -- no offense -- and thus are always hugging the sun. Because of the laws of planetary motion, this close couple are always in a hurry. They travel so fast that one can actually observe their movement through the stars week by week.

Why don't you? Take some time this month and go out and do a little planet-watching yourself.

Until next time, clear skies!

Mark Ritter teaches astronomy in Temecula, and free podcasts of the "Skies Above" column can be found online at the iTunes Music Store.