Four solar system objects meet in front of the constellation Gemini the Twins before sunrise tomorrow (August 4, 2013). The waning crescent moon and the dazzling planet Jupiter will be hard to miss, as they’re the two brightest celestial objects to light up the predawn and dawn sky. Mars and Mercury will demand more effort, though they may be visible to the unaided eye in a clear sky.
You probably won’t see the stick figure of the constellation Gemini in the glow of dawn tomorrow, as exhibited on the above sky chart. However, Gemini’s two brightest stars – Castor and Pollux – may well be visible to the north (left) the moon and morning planets. Bring along binoculars, if you have them, as they’ll enable you to view Mars and Mercury more easily, and the Gemini stars in the glow of the brightening dawn.
Note the ecliptic on the above chart. The ecliptic is Earth’s orbital plane projected onto the constellations of the Zodiac. The planets are always found on or near the ecliptic because all solar system planets orbit the sun on nearly the same plane that Earth does. The constellations of the Zodiac distinguish themselves from the other constellations because the sun, moon and planets routinely pass inside their borders.
The moon will pass out of the constellation Gemini and into the constellation Cancer in a day or two. Mercury will do likewise on August 7, 2013. Mars will follow suit on August 25, 2013, whereas slow-plodding Jupiter won’t reach the border of Gemini and Cancer until early July 2014.
Bottom line: Four worlds are gathered together in front of a single zodiacal constellation, the legendary Gemini the Twins: the moon, Jupiter, Mars and Mercury. You can see them all on Sunday, August 4, 2013.