May Skychart; Northern Hemisphere gazers guide
All month: Venus, in the west, Jupiter and Saturn, in the east, make for an interesting sky in May, in a number of ways. Venus is now well located as an evening object, coming out of the twilight soon after sunset, high and bright, setting after dark. You should definitely make a point of looking on the 15th, when the crescent moon joins the bright planet. Two bright stars above Venus toward the end of May are Pollux and Castor.
Jupiter and Saturn are in the east early at night, in the west at dawn. Saturn is already well up the eastern sky at sundown, just to the left of Spica, the brightest star of Virgo, and very near it in brightness. Jupiter isn't visible until an hour or so after dark, when it clears the haze near the horizon. The reddish star below it at night is Antares, in Scorpius.
May 1: The moon rises tonight at about 11 o'clock, just above the ''teapot''-shaped group of eight stars that mark the constellation Sagittarius. The waning gibbous moon, about three days before last quarter, will brighten Earth and sky until dawn. The moon is in conjunction with Neptune today, but the planet cannot be seen without a telescope. Mercury is stationary among the stars (relative to its movement east or west) late on the 1st, and now begins to move westerly (retrograde) as it approaches the sun.
May 3-5: The moon is at apogee (the position in its orbit farthest from Earth), before dawn on the 4th. It rises at about 1 a.m. in Capricornus. Late on the 4th, it reaches last-quarter phase (where it is 90 degrees - or one-fourth of the sky - to the sun's right). If you watch at sunrise on the 5th, you will see that the sun is just above the horizon in the east, and the moon is high in the south. Experienced navigators use the moon's phase and its position to orient themselves in direction.
May 5-6: Jupiter is above the star Antares tonight.
May 8: The waning crescent moon is in the sky from about 3 a.m. onward. It is still ''fat'' and bright enough so that you should see it easily from twilight into daylight, if the sky is clear. At about 10 a.m. it is about due south of the Vernal Equinox, in Pisces.
May 12: New moon occurs today, in the constellation Aries.
May 14-15: The young crescent moon may be visible on the evening of the 14th, but it will surely be prominent (weather permitting) soon after sundown on the 15th. Look toward the sunset glow on both nights. The reddish star well below the moon and to the right is Aldebaran in Taurus, though it may be lost in the murk near the horizon long before it sets. Venus is much brighter, higher and easy to see, above and to the moon's left on the 14th, above and much closer to the crescent on the evening of the 15th. Conjunction, when the moon passes Venus , is 8 p.m. Eastern standard time (EST).
May 16: The moon is at perigee, nearest Earth today.
May 19: First-quarter moon occurs today at 9:17 a.m., EST. The moon is in Leo tonight, high in the south at sundown, setting about 1 a.m. standard time. The bright star to the moon's right is Regulus. Note the circular group of stars above Regulus, forming, with the bright star as the ''dot,'' a backward question mark. This group is the key to finding Leo, with the circular group of stars suggesting his head and Regulus his heart. When the moon isn't nearby to help you, try following the ''pointers'' of the Big Dipper, in a direction opposite the path toward the North Star.
May 21: The gibbous moon, two days after first quarter, is in Virgo, directly above the point on the sky called the Autumnal Equinox, where the sun is situated on Sept. 23. The two bright objects well to the east (left) are Spica and Saturn.
May 23: The moon is in conjunction with Spica this morning, with Saturn this evening. After sundown, Saturn will be beneath the moon, Spica to their right. The bright object much farther left and closer to the horizon is the planet Jupiter.
May 24: Mercury ends its retrograde (westerly) motion.
May 26: Full moon occurs at 1:48 p.m., EST, in Scorpius. After sundown, when the moon rises, it is moving into Ophiuchus, very closely above the bright planet Jupiter. At about 4 p.m., when the moon passed Jupiter, it covered the planet (an occultation) in the sky over parts of Europe, Asia, and Africa.
May 27: Jupiter is at opposition with the sun today, and it becomes an evening star. The change from morning to evening sky makes little difference in the visibility of the planet, at least for a while. It continues to rise in the east during the early hours of the night, set in the west in the morning. But from now on it will gradually become more prominent as an evening star, less prominent in the morning.
May 31: Venus drifts past Pollux and Castor, Gemini's ''twin'' stars, this evening, passing Castor (the higher and dimmer of the two stars) first and then Pollux, the latter at about midnight (2400 hours), EST.