Tonight the nearly full moon will become part of the Winter Hexagon, one of the biggest and easiest to see asterisms of the winter sky. You’ll find Luna twixt Procyon in Canis Minor and Pollux in Gemini along the eastern side of the figure which is comprised of six bright stars. When connected by imaginary lines, the stars form a hexagon 65° tall by 45° wide that reaches from the zenith to low in the southern sky.
The moon’s 240,000 miles from Earth and 2,160 miles (3,475 km) in diameter. To get there by foot would take you 9 years. Seen from Earth, the lunar sphere spans just 1/2° of sky – you can more than cover it up with the tip of your pinkie finger.
Yesterday we replaced the Sun with Polaris, Vega, Sirius, Alpha Centauri and Arcturus to get a feel for the real dimensions and appearance of what are otherwise tiny twinkling points of light.
Today we’ll replace the moon with several of the planets to better appreciate their true dimensions. Like the stars, all the planets look like dots of light to the unaided eye.