Until Mercury moves past the sun into the evening sky on March 8, all planets are morning stars. Mercury and Venus, though, are too close to the sun all month to be visible, being in the sky only during daylight or bright morning twilight. The outer planets Uranus, Neptune, and Pluto, though well-placed morning stars, are too dim to be seen. But we will have good views of Mars, Jupiter, and Saturn, more than making up for the absence of Venus.
The planet show begins this month about 10 p.m. (an hour or so later in early March, a bit earlier at the end of the month), when Saturn rises among the dim stars of Libra, followed about an hour later by Mars. Earlier in the year, Saturn was easily the brighter of the two, but Mars brightened in February to equal and then surpass Saturn as the two exchange places as ''first up'' in the morning sky. Now Mars is clearly the brighter, reaching over double the shine of Saturn by the end of March, though still no match for Jupiter. The latter planet , rising more than two hours after Mars, is by far the brightest ''star'' you see on March nights this year.
Though Saturn and Mars are up before midnight, best viewing time for the planets in March is still the early morning darkness before dawn breaks, when all three - Saturn, Mars, and Jupiter - are high and clear of the horizon. Brightness and position guide you to them easily; they are set in the southeast sky where they stretch out in line from brilliant Jupiter upward and toward the south. Together with Antares and Spica, brightest stars of Scorpius and Virgo respectively, they form a string of five bright objects easily recognized.
Begin with Jupiter, brightest and lowest. Next upward and toward the right is ruddy-looking Antares, dimmest of the five; then Mars, second brightest; and finally Saturn, which is close to Mars, and Spica, the more distant, though similar to Mars in appearance.
If you look for these morning planets repeatedly during March, you should notice Mars brightening as it approaches early May's opposition from the sun. Mars also slowly separates from Saturn and approaches Antares during the month. Above all, look for these three during the last third of March when the waning moon is moving through that part of the sky, passing each bright star and planet in turn.
The events described in the calendar are in local time unless otherwise indicated.
March 1-2: No moon is visible on either night. It's new (between sun and Earth) on the 2nd, and can only be seen in the constellation Aquarius during daylight or very bright twilight. It's also farthest from Earth (apogee) on the 2nd.
March 4-5: You might see the slender crescent moon on the evening of the 4th if the sunset sky is exceptionally clear, though surely on the 5th. On both evenings it is near the southern border of Pisces. This month's new crescent moon is in a particularly favorable position for viewing, standing high in the twilight after sundown, setting an hour later on successive nights.
March 6: The crescent moon is easily visible tonight just as it enters the constellation Aries. Look above the moon for the ram's two bright stars, Hamal (the brighter) and Sheratan.
March 8: Mercury is in superior conjunction (in line with the sun, but opposite Earth). Swinging from right to left of the sun, it becomes an evening star.
March 10: First quarter moon (at 1:27 p.m., Eastern standard time) is still in Taurus when you see it tonight. Just after sundown, it will be very high in the south, with all the bright stars of Orion displayed below it.
March 12: Tonight's waxing gibbous moon is moving through the western part of Gemini. If you watch it occasionally from dusk on, you will see it move into line with Gemini's two bright stars (Pollux below and Castor), the ''Twins'' of the constellation. It moves out of line with them after midnight, going into Cancer.
March 14-15: The moon is in the Lion on these nights, passing above Leo's brightest star, Regulus, during the day on the 15th. You will see Regulus to the moon's left on the night of the 14th, to its right on the 15th.
March 16-17: Perigee moon (4 p.m. EST, on the 16th) and full moon (5:10 a.m. EST, on the 17th) occur this night, close enough in time to produce perigee spring tides during the day of the 16th. The moon crosses into Virgo early at night. High tides during the morning and evening of the 17th will be exceptionally strong.
March 20: The sun is in the constellation Pisces today, at the position above the equator known as the vernal equinox. Winter ends and spring begins in the Northern Hemisphere at 5:25 a.m. EST. The length of the day (from sunrise to sunset) has exceeded the night since March 17.
March 20-21: After moonrise tonight (about 10 p.m.), you can easily find Saturn and Mars to the right and left of the moon respectively. The moon is between them, moving slowly away from Saturn toward Mars. It passes Saturn at about 1 p.m. EST on the 20th, Mars at about 8 a.m. on the 21st, covering both as it passes. The occultation of Saturn is visible over the Indian and western Pacific Oceans, of Mars over the South Pacific.
March 21-22: The waning gibbous moon rises close to midnight tonight. Mars and Saturn are in line to its right and above, while below to its left, rising later, you will find the reddish star Antares, in Scorpius.
March 24: Last quarter moon, in Sagittarius, occurs at 2:58 a.m., EST. Now a waning object, rising after midnight, the moon joins the brighter planets in a beautiful display during pre-dawn hours for the next several days. This morning, very bright Jupiter is close by (to its left and below), while Mars and Saturn are well up (toward the southeast) and to the moon's right.
March 29: For the second time this month, the moon is at apogee (farthest from Earth). Now a very slender crescent in Aquarius, it rises too late in the morning sky to be visible. Even brilliant Venus, nearby the crescent today and tomorrow, is hidden by the dawn glow.