It’s Monday, May 6, 2013, and … where’s the moon? We’ve had questions from people asking why they can’t see the moon in the night sky. The moon is still up for part of every night. But – around May 6 – it’s the part of the night when most of us are sleeping. The moon is rising in the east a short while before sunrise right now. It’s a waning crescent phase, and the moon will have its new phase in a few days.
Take advantage of the dark, moonless skies to find the constellation Hercules the Strongman tonight. You’ll need a dark sky to see this mighty star figure. But if you can see Vega – a prominent blue-white star in the northeast in the evening now – you might spot Hercules nearby.
The most noticeable part of Hercules is an asterism or noticeable pattern of stars – in this case a lopsided square – in the center of this constellation. This asterism within Hercules is called the Keystone. It’s all most people ever see of this large constellation.
But Hercules extends beyond its central Keystone. This constellation is in fact quite large and in ancient times was sometimes called the Kneeling Giant. Hercules also appeared in the skylore of western skywatchers in the Middle East, where it represented Gilgamesh, an epic hero of Sumerian and Babylonian mythology.
The brightest star in Hercules isn’t in the Keystone, either. It’s Ras Algethi, which is known to people with telescopes as a double star with a pretty color contrast, one red and one blue. Just don’t confuse Ras Algethi with nearby Rasalhague, which is the brightest star in the constellation Ophiuchus the Serpent Bearer. Rasalhague is white, while Ras Algethi appears red.
And don’t forget a hidden treasure within Hercules – visible to those with telescopes. It’s M13, sometimes called the Great Cluster in Hercules. It’s a globular star cluster within our Milky Way galaxy.
Bottom line: On May 6, 2013 moon is in a waning crescent phase. You’ll find it in the sky shortly before sunrise. Take advantage of the dark evening skies. Look near the star Vega for the constellation Hercules and its famous Keystone asterism!