February will be a good month for planets. All the visible planets except Mars, which is too close to the Sun, will be in the sky during at least some of the evenings. For most of every night, very bright Jupiter will outshine everything in the sky except the Moon. It will be unmistakable to the right of Pollux and to the lower right of Castor, the bright twin stars in the constellation Gemini (the Twins). Saturn also will be unmistakable during February evenings, shining low in the southwest in a dim part of the sky. It will set at about 9:00 early in the month and at about 7:00 at the end of February.

During midmonth, fleet Mercury will make a brief visit to the early evening sky. Although this will be its best evening appearance for the year, Mercury will never get very high above the western horizon. On February 18, Mercury will be at its highest point and just above a very thin crescent Moon before they set near the end of twilight. This is an excellent opportunity to see the elusive planet. Finally, brilliant Venus will complete the planet parade as it climbs above the western horizon in the last part of the month.

The very thin crescent Moon, which is only visible just after sunset or just before dawn, is one of the best sights in astronomy, and its close pairing with Mercury will make this one even more special. However, any very thin crescent Moon has intrinsic beauty and two special sights to enjoy. The first has long been known as “the old Moon in the new Moon’s arms.” This refers to when the crescent holds the rest of a dimly lit Moon within it. The accepted astronomical name for this glow is earthshine, and it is caused by the Sun’s light reflecting off the Earth and making the Moon dimly visible.

The other sight is best seen through binoculars or a telescope. When either is used, the inner edge of the crescent will look rough. This is caused by mountains that are sunlit and valleys that are in the dark. The floors of craters also may be dark because they are in the shadow of their walls. If you look at the ends of the crescent you might see bright islands surrounded by the blackness of space. They are mountain peaks catching the first rays of the Sun. The thin crescent Moon is truly special.

Observing Highlights

Feb. 2: The Moon will rise just before Regulus, the brightest star in Leo (the Lion), at about 7:00. In the northeastern parts of the U.S., the eastward motion of the Moon will take it over and hide Regulus. In central Iowa, the occultation will begin close to the eastern horizon at about 7:40 CST and end at about 8:40 CST. The event will be visible at slightly different times elsewhere. In the western states, the Moon will be very close to Regulus. Everywhere the very bright Moon will make it hard to see Regulus without binoculars or a telescope.

Feb. 7: After they climb into good view after midnight, the Moon will be close to the lower right of Spica, the brightest star in the constellation Virgo (the Maiden). They will cross the sky together until dawn.

Feb. 11: In the hours before dawn, the Moon will be just east of Antares, the bright heart of Scorpius (the Scorpion).

Feb. 18: Mercury will be at its highest point, but still close to western horizon. It will look like a bright star just above the very thin crescent Moon. Look about 30 to 45 minutes after sunset.

Feb. 19: The crescent Moon will be close to the upper right of Saturn at nightfall.

Feb. 23: The Moon will be to the right of the Pleiades (or Seven Sisters) open star cluster, although binoculars may be needed to tease the cluster out of the Moon’s bright light. Aldebaran, the brightest star in the constellation Taurus (the Bull), will be farther to the lower left of the Moon.

Feb. 27: Just after sunset on February 27, Venus will pass close to the left (southward) of departing Mercury. At nightfall, the Moon will be in line with Pollux and Castor above Pollux, the bright twin stars in Gemini (the Twins). Very bright Jupiter will be to the upper right of the Moon and to the right of the twin stars.