Tonight – February 21, 2018 – use the waxing crescent moon to find the relatively faint constellation Aries the Ram. The moon is riding along the southern border of this constellation tonight, so seek for the major stars of Aries to the north (or right) of tonight’s moon. The only prominent part of this constellation consists of the three stars that make up the head of Aries. In their order of brightness, the stars outlining the Ram’s head are Hamal, Sheratan and Mesarthim.
The Ram’s hindquarters are marked by the star 41 Arietis, which is almost – but not quite – in line with the Ram’s two brightest stars, Hamal and Sheratan. The Ram is often portrayed as looking over his shoulder, admiring the Pleiades star cluster or perhaps his own Golden Fleece.
Sky chart of the constellation Aries the Ram
The ecliptic on the above chart depicts the pathway of the sun in front of the constellations of the zodiac. Yearly, from about April 18 to May 13, the sun passes in front of Aries the Ram, at which time of year Aries is lost in the light of the sun.
The moon, on the other hand, is always found in the vicinity of the ecliptic – but not necessarily on the ecliptic – when it makes its monthly travels through the constellation Aries. Depending on the year and month, the moon can swing anywhere from 5 degrees (10 moon diameters) north to 5 degrees (10 moon diameters) south of the ecliptic when traveling though Aries (or any constellation of the zodiac). Tonight, on February 21, 2018, the moon goes farthest south of the ecliptic for this month as it passes through the constellation Aries.
Click here and then scroll down to Moon Ecliptic Latitude to know how far north or south the moon is from the ecliptic at present or for any chosen date. Remember, a positive number means north of the ecliptic while a negative number means south of the ecliptic.
Click here to see a pictorial display of the moon’s position in front of the zodiac and relative to the ecliptic for right now or any given date.
Bottom line: Tonight – February 21, 2018 – watch the waxing crescent moon light up the evening sky as it dances along the southern boundary of the constellation Aries the Ram.
Bruce McClure has served as lead writer for EarthSky's popular Tonight pages since 2004. He's a sundial aficionado, whose love for the heavens has taken him to Lake Titicaca in Bolivia and sailing in the North Atlantic, where he earned his celestial navigation certificate through the School of Ocean Sailing and Navigation. He also writes and hosts public astronomy programs and planetarium programs in and around his home in upstate New York.