Last modified: Tuesday, March 2, 2004
Five planets parade across the evening sky
BLOOMINGTON, Ind. -- With a single sweep of the eye across the evening sky in March, you can see all five of the planets that are visible with the unaided eye.
Venus, the brightest planet of all, will be a gorgeous "evening star" high in the west at sunset, easy to spot even in bright twilight. Venus will reach its highest point above the horizon in late March, setting four hours after the sun. This is the highest Venus has been in the evening since 1996. It won't happen again until 2012, so enjoy it while you can.
Moving eastward across the sky, the next planet in line will be Mars, where the Spirit and Opportunity rovers are exploring the surface. The red planet will appear as a faint orange dot to the upper left (south) of Venus. Mars and Venus will move toward each other as the month passes, with the Pleiades star cluster between them until Mars passes it on March 19.
Farther eastward, Saturn will be high in the south-southeast by the end of evening twilight. The bright yellow planet will be in the constellation Gemini the Twins, high above the familiar bright stars of the constellation Orion the Hunter and well-placed for viewing with a telescope for several hours after sunset. This winter is the best time in 30 years to see Saturn with a telescope. The planet is closest to us in its orbit, and its rings are tilted toward us almost the maximum amount.
Jupiter, the largest planet and second only to Venus in brightness, will be low in the east as darkness falls, as if to offset Venus high in the west. Jupiter will be at opposition (opposite the sun) and therefore biggest and brightest on the night of March 3-4, rising at sunset and remaining visible all night. This is the best time of the year to see Jupiter's four largest moons with binoculars, when it is high in the southern sky, and also the best time for viewing its surface with a telescope.
To Jupiter's lower right (south) will be Sirius, the brightest actual star in the sky of the Northern Hemisphere. The line of three bright stars in Orion's belt always points almost directly to Sirius to the left (east). If you watch Sirius carefully on a clear night, you can see it twinkle in different colors in addition to its usual brilliant white.
Mercury will join the parade of planets after mid-month, when it will be to the lower right (west) of Venus close to the western horizon a half hour after sunset. The small planet will quickly move higher as the days pass, reaching its greatest elevation near the end of the month on the same day that Venus peaks. This will be Mercury's best evening appearance of the year for viewers in the Northern Hemisphere, and it will be easy to find below brilliant Venus.
The sun will cross the celestial equator (an extension of Earth's equator onto the sky) on March 20 at 1:49 a.m. EST (6:49 Universal Time) heading north. The March equinox marks the start of spring in the Northern Hemisphere and fall in the Southern Hemisphere. For the next six months in the Northern Hemisphere, the days will be longer than the nights.
Followers of many religious faiths around the world observe days of celebration during March and April as spring returns to the Northern Hemisphere. Most of these days are linked in some way to the March equinox. For example, each year Easter falls on the first Sunday after the first full moon after March 20, the most common date of the equinox.
Day and night are not precisely the same length at the time of the equinox. That happens on different dates for different latitudes. At higher latitudes in the Northern Hemisphere, the date of equal day and night occurs before the March equinox. In the Southern Hemisphere, this happens after the March equinox. Information about exactly when the equinox happens at different places on Earth's surface is provided by the U.S. Naval Observatory at http://aa.usno.navy.mil/faq/docs/equinoxes.html.
The moon will be full on March 6, at third quarter on March 13, new on March 20 and at first quarter on March 28.