Jupiter’s moon Io and its tiny shadow sweep across the giant planet’s face back in 1999, as snapped by the Hubble Space Telescope. This week, backyard telescope users get a chance to witness the shadows of three of Jupiter’s moons. Credit: John Spencer (Lowell Observatory) and NASA
Sky-watchers double down on shooting stars this week, while the largest planet in the solar system plays host to a rare triple play of tiny moon shadows racing across its face.
Moon joins Venus. After sunset on Monday, October 7, and again the next evening, watch for the thin crescent moon gliding past the brightest planet in the sky, Venus. Sitting not far from the sun this week, the planet named for the Roman goddess of love will be fairly close to the southwest horizon, especially for mid-latitude observers, making binoculars a great tool for picking the planet out from the sunset glow.
Draconids peak. Look toward the high northwest skies starting after nightfall on Monday and then again on Tuesday, October 8, for the minor Draconid meteor shower.
Like most meteor showers, the Draconids are named after the constellation from which they appear to radiate—in this case, Draco, the dragon.
At the shower’s peak, Draco will be nearly overhead around local midnight throughout the Northern Hemisphere. Draconids are best viewed from when darkness falls until midnight, when the constellation is at its highest in your local skies. The dragon’s shooting stars are fairly easy for beginner sky-watchers to see, since the stars are considered some of the slowest moving of any shower.
The flurry of meteors actually comes from a stream of sand grain-size particles spread along the orbit of the comet 21P/Giacobini-Zinner. When Earth slams into this debris stream, the comet particles disintegrate in our upper atmosphere, creating streaks of light.
Venus triangle. At dusk on Tuesday, October 8, the moon will rise to the upper left of Venus to form an equilateral triangle with the bright orange star, Antares, which is some 600 light-years away from Earth.
Southern Taurid meteors. In the predawn hours of Thursday, October 10, look toward the southern sky for another minor meteor shower. The Southern Taurids are set to peak around 2 a.m. local time, after the moon sets, and promise about five shooting stars per hour. The Taurids tend be brighter and slower moving than the average shower, making them fun to watch even from city suburbs.
First-quarter moon. On Friday, October 11 (7:02 p.m. EDT/23:02 UT), the moon, half lit, will appear perched above the constellation Sagittarius, marked by the stellar “teapot” pattern, which is visible low in the southwest evening sky.
Triple shadows on Jupiter. In the early morning hours (12:32 to 1:37 a.m. EDT/4:32 to 5:37 UT) of Saturday, October 12, backyard telescope users will be able to glimpse a rare sight—the shadows of three moons of Jupiter as they transit across the planet’s disk.
Three of Jupiter’s largest moons, Io, Europa, and Callisto, will cast their tiny dot-like shadows at the same time onto the upper cloud deck of Jupiter.
Callisto’s shadow is the first to appear, at 11:12 p.m. EDT on Friday night, followed by Europa’s shadow at 11:24 p.m. and finally Io’s little shadow at 12:32 a.m.—after which all three tiny dots will cross simultaneously across the planet’s disk.
The best views will be from Africa, Europe, and the eastern coast of North America. If you miss this one, the next chance you’ll get for a Jovian moon triple play is on June 3, 2014.
Tell us—what amazing sky phenomena have you seen lately?