Venus returns to evening skies this month, shining as the "evening star" quite low in the west at nightfall by month's end. By that time, its only rival in the night sky, brilliant Jupiter, is dropping toward the Sun and getting ready to exit the evening sky. In the meantime, one of the signature constellations of summer, Scorpius, skitters into view in late evening, preceded by the scorpion's long-lost claws, the stars of Libra, the balance scales.
This Week's Stargazing Tips
May 19
M13, the Hercules Cluster, stands in the east at nightfall, in the constellation Hercules. To the eye alone it looks like a small, hazy patch of light. Small telescopes reveal hundreds of the cluster’s individual stars.
May 20
The Moon is in its “gibbous” phase, which means that sunlight illuminates more than half of the lunar hemisphere that faces our way. The dark portion of the lunar disk is in the Moon’s own shadow, so it is night on that part of our satellite world.
May 21
The Moon takes aim at one of the brightest stars in the night sky tonight: Spica, the main star of the constellation Virgo. Spica is close to the lower left of the Moon as night falls, and even closer to the Moon as they set before dawn tomorrow.
May 22
The planet Saturn perches to the left of the Moon as night falls this evening. It looks like a bright golden star. The true star Spica stands to their upper right.
May 23
A pair of hunting dogs chases high across the north tonight. Known as Canes Venatici, the hounds are pursuing Ursa Major, the great bear, which stands below them at nightfall. The bear includes the stars of the Big Dipper.
May 24
A new cycle of eclipses begins tonight as the full Moon just dips its toe in Earth’s faint outer shadow, the penumbra. That shadow will cover just about one percent of the lunar disk, but it is so faint that no one will notice the difference.
May 25
A beautiful bit of cosmic theater plays out very low in the west-northwest shortly after sunset the next few evenings. The dazzling planets Venus and Jupiter will slide past each other, while a fainter third planet, Mercury, watches from above.
Check last week's tips if you missed a day.
