SkyEye

The Calendar

Mars, Jupiter and Saturn are found close together during the latter half of the month. Venus continues its reign as the slowly-brightening evening star and Mercury dazzles early morning observers in the southern hemisphere.

The Solar System

The word planet is derived from the Greek word for 'wanderer'. Unlike the background stars, planets seem to move around the sky, keeping mostly to a narrow track called the ecliptic, the path of the Sun across the stars. Dwarf planets and small solar-system bodies, including comets, are not so constrained, often moving far above or below the ecliptic.

Sun Aquarius → Pisces

The solar south pole is most inclined toward the Earth early this month.

Mercury Aquarius → Capricornus → Aquarius

Now past inferior conjunction, Mercury is a morning sky object, brightening from fourth magnitude at the start of the month to zero magnitude by the end. This is a poor apparition for observers in northern temperate latitudes but the best morning appearance of the year for observers in the southern hemisphere. Mercury completes retrograde motion on 9 March and it reaches greatest elongation west of 27.8° on 24 March. This is the largest distance from the Sun that the tiny planet attains this year. Aphelion occurs three days later.

Venus Pisces → Aries → Taurus

The evening star moves past Uranus on 8 March, with the two planets coming within 2.2° of one another. Because the sky will not be dark, optical aids will be necessary to spot the sixth-magnitude outer planet. On 20 March, Venus reaches perihelion and four days later, undergoes greatest elongation west (46.1°). This evening apparition of Venus favours northern observers, with the bright planet reaching over 40° in altitude at sunset. When seen through a telescope, the illuminated fraction of the disk reduces from 63% to 47% over the course of the month so that the shape goes from waning gibbous to waning crescent. However, the planet is also drawing closer to Earth so its apparent size is increasing. Venus actually brightens slightly from magnitude −4.2 to −4.4 by the end of March.

Earth and Moon

The waning crescent Moon occults Mars on 18 March. Earth reaches the first of two equinoxes two days later. The word equinox means 'equal night' so that on this day, the (centre of the) Sun spends an equal amount of time above and below the horizon everywhere on the planet. On 24 March, the Moon reaches its farthest apogee of the year.

Mars Sagittarius → Capricornus

First-magnitude Mars presents a small, slightly gibbous appearance in telescopes this month. It will grow larger and brighter as it approaches opposition in October. The red planet is occulted by the waning crescent Moon on 18 March in an event beginning around 06:30 UT. Mars passes 0.7° south of the much brighter Jupiter on 20 March and then overtakes Saturn on the last day of the month. All three superior planets are morning sky objects and are most easily observed from southern latitudes.

Jupiter Sagittarius

Jupiter continues to draw away from the Sun in the morning sky. At magnitude −2.0, it is the brightest non-lunar celestial object in its part of the sky. The waning crescent Moon passes 1.5° south of Jupiter on 18 March. Two days later, it is the turn of Mars to glide past the gas giant. The two planets are only 0.7° apart at their closest approach, with Mars a reddish magnitude +0.9 and Jupiter a brilliant −2.1. The largest of the planets rises before midnight when viewed from the southern hemisphere but appears only just before morning twilight for astronomers watching from northern temperate latitudes.

Saturn Sagittarius → Capricornus

Saturn shines at a steady magnitude +0.7 this month. Although it is slowly getting closer to Earth as it approaches opposition in July, the tilt of the rings is lessening so the planet is not getting brighter this month. The waning crescent Moon passes just over 2° south of Saturn on 19 March and red Mars is less than a degree away on the last day of the month. Look for Saturn in the vicinity of Mars and Jupiter this month during the early morning hours.

Uranus Aries

Binoculars or a small telescope will be necessary to see sixth-magnitude Uranus in the company of bright Venus in the evening twilight on 8 March when the two planets are just over 2° apart. The best views of this event are from the northern hemisphere.

Neptune Aquarius

Neptune is at conjunction this month and is lost in the glare of the Sun.