The sky in March

Natural History, March, 2004 by Joe Rao

From March 15 through April 5, all five of the planets readily seen without a telescope will be visible simultaneously in the early evening sky. Throughout that period, about an hour after sunset, they will be stretched across the sky, in this order from west to east: Mercury, Venus, Mars, Saturn, and Jupiter.

Swift Mercury passes behind the Sun on March 4, reaching what is known as superior conjunction, then races around our star toward Earth. By the 16th Mercury is readily visible a little above the western horizon, shining at magnitude -1.3; it sets an hour after the Sun. The planet should be easy to find during the second half of March; in fact, for viewers in the northern hemisphere, this apparition is its best of the year. It reaches its greatest elongation (the farthest east it gets from the Sun) on the evening of the 29th. By that time it shines at magnitude zero and sets shortly after twilight ends.

Venus grows ever more brilliant during March, reaching magnitude -4.4 by month's end. The planet reaches its greatest elongation on the 29th (forty-six degrees from the Sun)--the same day as Mercury's. Venus remains in view for about four hours after the Sun goes down. On the evening of the 24th, Venus is about two degrees from a lovely crescent Moon; by month's end the planet shines south of the Pleiades.

Mars begins March in the constellation Aries, the ram, and crosses into the constellation Taurus, the bull, on the 13th. It appears high in the west-northwestern sky at dusk and sets between 11 P.M. and 11:30 P.M. local time all month. The Red Planet continues to dim as it moves away from Earth. On the evenings of the 20th and 21st, Mars shines about three degrees south of the Pleiades. On the evening of the 25th, the fat crescent Moon passes closely to the north of Mars. For those living across northern Canada, in Greenland, and in Iceland, the Moon appears to occult, or hide, Mars.

Jupiter, in the constellation Leo, the lion, shines as a brilliant silver "star" low in the eastern sky as dusk arrives. The giant planet reaches opposition to the Sun on the 4th. At the beginning of March, Jupiter is some thirty degrees above the eastern horizon by 8:30 P.M. local time; it rises earlier as the month progresses. A small telescope--or even steadily held seven-power binoculars--reveals Jupiter's prominent cloud belts as well as its four brightest satellites. Make a special effort to have a look on the evening of the 4th; around 10 P.M. the four satellites appear as similarly spaced pairs on the same side of Jupiter. Europa and Io are the closest in, whereas Ganymede and Callisto appear farther out.

Saturn, in the constellation Gemini, the twins, shines high in the east-southeastern sky at dusk all month. It sets shortly after 3 A.M. local time on the 1st, and about two hours earlier by month's end. The planet is at east quadrature (ninety degrees east of the Sun) on the 26th, and so from Earth we can more readily see the dark shadow the planet casts on its rings, giving greater depth of appearance to both.

The Moon waxes full on the 6th at 6:14 P.M. and wanes to last quarter on the 13th at 4:01 P.M. Our satellite is new on the 20th at 5:41 P.M. and waxes to first quarter on the 28th at 6:48 P.M.

The equinox occurs at 1:49 A.M. on the 20th.

Unless otherwise noted, all times are given in Eastern Standard Time.