Spring's Planetary Spectacle

Please note: this article is written for mid-northern latitudes.

As if in celebration of the beginning of spring, all five planets that can be seen by the naked eye will be together in the evening skies this month. This opportunity will happen again in December/January 2005 but afterwards not for 32 years!

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It's possible to see all these planets because they are all on the same side of the Sun (if we were viewing the Solar System from above.) Four of the planets, Venus, Mars, Saturn and Jupiter can be seen now. Mercury, the most difficult to spot, won't be visible until late March. Mercury, because it is so close to the Sun, is never high in the sky and only visible near dawn or dusk.

Venus, Jupiter and Saturn are the easiest to spot and can even be seen from towns. Mars is more dim, but can still be very easily found in darker skies. Mercury is the most difficult to find because it is so close to the Sun.

From our viewpoint, the planets appear to move along in their orbits against the starry background at their own speeds. The closer a planet is to the Sun, the faster it moves. All of the orbits, however, closely follow an imaginary line in the sky called the ecliptic.

The ecliptic is the apparent path that the Sun takes across our sky as a result of the Earth's rotation. The constellations of the zodiac are all along the ecliptic and the word zodiac comes from the Greek word zodiakos, which literally means circle of animals.

Our ancestors noticed that the planets moved among the background stars, in fact, the origins of the word planet are Greek for "wanderer." It was this almost mystical ability of the planets to move among the stars that earned them names after the Gods.

Mercury is named for the winged Roman god of travel because it moves so swiftly. Venus is named for the Roman goddess of love and Mars for the Roman god of war. Jupiter, the largest and most massive of the planets was named Zeus by the Greeks and Jupiter by the Romans. Saturn was the Roman name for the Greek Cronos, god of farming and the father of Zeus/Jupiter.

So, where to find these wanderers? Venus is the most obvious, outshining all stars and planets in the western sky at sunset. Reddish Mars, much dimmer than it's brilliant self last autumn, can be found high in the southwestern sky not far from the Pleiades. Saturn is almost overhead at dusk, in the feet of Gemini the twins. Brilliant Jupiter rules the eastern sky, rising at sunset at the feet of Leo the lion.

You will have to wait until late March to spot Mercury, then it will be as high as possible for mid-northern latitudes, and offer the best chance to spot it. Look for this elusive planet just above the setting Sun in the west.

Here are some dates for specific events:
March 22 - At dusk look for a thin crescent Moon low in the west to the upper left of Mercury.
March 24 - The crescent Moon appears close to Venus.
March 25 - The Moon will appear close to Mars.
March 27 - All five visible planets will span 135 degrees across the sky.
March 28 - First quarter Moon will appear just above Saturn.
April 2 - A waxing gibbous Moon will appear to the lower left of Jupiter.

Happy Stargazing!

Constellations

The Solar System