The Planets

Mercury puts on its best evening apparition of the year, and it is well placed for viewing in the W after sunset for the first half of the month. For the first few days of May it lies near the Pleiades, and on the 6th, a 2-day old crescent Moon passes 3° to Mercury's upper right. The planet reaches its greatest eastern elongation (22° E of the Sun) on May 13-14. A telescope will then show a 37%-lit disk 8" across. By the third week of May it will have started to fade and get ever closer to the Sun.

Mars starts out the month high in the SW during early evenings, forming nearly a line with Castor and Pollux - the "Twin Stars" of Gemini. On May 9, the waxing Moon is 6° to its W, and on the following night is 6° to its E. On the evenings of the 21st through 23rd, it makes a picturesque passage through the Beehive Cluster (M44). Mars averages about magnitude +1.4 during May. A telescope reveals a tiny disk less than 6" across.

Saturn far outshines nearby Regulus, Leo's brightest star. Even a small telescope will reveal its magnificent rings - now 41" across but only 7" high, encircling the 18"-diameter globe. The rings are now inclined to us by only 10°, and will be edge-on next year. Also look for its brighter moons, including Titan (at magnitude 8.3), Rhea (9.7), Tethys (10.3), Dione (10.4), and Enceladus (11.7). Iapetus presents its snow-white "bright" side to us most of this month, and reaches magnitude 10.1 when it is at its greatest western elongation on May 17.

Jupiter rises an hour after midnight on May 1st, but around 11 PM by the end of the month. It lies in Sagittarius, just E of the "Teapot" asterism. It grows from 41" to 45" across during the month, more than enough to reveal many atmospheric features, including the major dark "belts" and light "zones" in its dynamic atmosphere. Also easy to see are its four major satellites: Io (magnitude 5.5), Europa (5.8), Ganymede (5.1), and Callisto (6.1).

Neptune is visible in the E an hour or two before sunrise. Binoculars or a small telescope will show the 7.9-magnitude planet about 2.4° N of Delta Capricorni, but it takes a larger instrument to show anything of its blue-white 2.3"-wide disk.

Uranus, at magnitude 5.9, is brighter than Neptune, but may be harder to see because it doesn't rise as high above the E horizon before dawn. It lies about 5° E of Phi Aquarii. An easy hint: on the evening of May 29, a waning crescent Moon lies between Kappa Piscium (the southernmost star of the "Circlet" of Pisces) and Uranus. A telescope displays the planet as a greenish-white 3.4" disk.

Venus is too close to the Sun to be visible.

Dwarf Planets/Asteroids

7 Iris, at magnitude 10, passes within 0.5° of the Sombrero Galaxy (M104) in Virgo between May 5-7 .