On Friday evening (May 17), look toward the southeast for a nearly full moon.  The moon appears between Zubenelgenubi and Zubeneschamali, the northern claw and the southern claw, respectively.  The stars are not overly bright, and the moon’s size is exaggerated in the image above.

Today the stars are the two brightest in Libra, the Scales.  This constellation is the only inanimate object in the zodiac, the constellations that the sun, moon, and planets appear to move through.

The two stars were once part of Scorpius, the Scorpion, that is now rising in the southeast below the moon.  The scorpion was divided into two constellations, but the two stars retained their original names.

So if you imagine that the scorpion is largely below the southeast horizon with its pincers up in the sky holding the moon on this evening.

Step outside as the sky darkens on Wed (May 15) and Thurs (May 26).  The moon appears to pass the bluish star Spica on the two evenings.  Spica is the brightest star in the constellation Virgo.

On May 15, the moon, 11.1 days past its New phase and 90% illuminated, appears 8° above Spica.

On the next evening, the moon, one day older and 92% illuminated, is over 11° to the left of Spica.

Across these two evenings you can see the moon’s eastward movement compared to the starry background.

We notice several changes in the moon:

• Phase:  The illuminated portion of the moon changes slightly each night, dramatically across a week.
• Daily Rising and Setting:  On a warm spring evening, notice the moon’s position, relative to nearby trees and houses, for an hour.  You see it get farther west during that time.  Like the sun, it rises in the eastern sky, sometimes southeast and sometimes northeast, and sets later somewhere in the west that mirrors its rising spot.
• Daily eastward orbital motion:  Each day, the moon moves slightly to the east.  In about 27 days appears near Spica again, but its phase is not quite the same as on these two nights.

Leo, the Lion, stands high in the southwest as the sky darkens in early to mid-May.  The shape is fairly easy to locate.  Six stars resemble a backwards question mark, also known as “The Sickle” for the farm implement.  A triangle trails farther east.  Regulus is the bottom star of the question mark and represents the lion’s heart.  Denebola marks the lion’s tail.  The celestial lion is majestically facing westward as we view its profile.  The moon moves through the region May 11-13, 2019.  Here’s what to look for:

• May 11: The moon reaches its First Quarter phase at 8:12 p.m. CDT. One hour after sunset, the moon, 7.1 days past its New Phase and 50% illuminated, is high in the southwest, 8.9° to the right of Regulus.

The angular degree measurement is used in astronomy to determine the separations and sizes of objects.  Because objects have various actual sizes and distances from Earth, the degree is the way for us to communicate apparent sizes and apparent separations.  The full moon has an apparent diameter of about 1/2°.  The charts we use typically exaggerate the size of the moon, so the chart cannot be used for a scale with the moon.  The distance from Regulus to Denebola is about 24°.

• May 12: One hour after sunset, the moon (8.1d, 62%) is 6.2° to the upper left of Regulus.
• May 13: The moon is closest to Earth at 4:53 p.m. CDT. An hour after sunset, the moon (9.1d, 73%), nearly 60° up in the south, is 8.5° to the lower right of Denebola– the tail of Leo.