On Sept. 5, the European Space Agency’s Rosetta deep-space probe flew past an asteroid located in the asteroid belt orbiting between Mars and Jupiter. The probe passed within 500 miles of the asteroid that is located 250 million miles from Earth.

Images will be sent to researchers working on the origins of the solar system. As mission manager Gerhard Schwehn said, “Dead rocks can tell a lot.”

Rosetta, which was launched in 2004, then will go on for a rendezvous with Comet Churyumov-Gerasimenko in 2014. Scientists will attempt to place a lander on the surface of the comet, which will be more than four times the distance from Earth to the sun at the time. The orbiting spacecraft and lander will send back data on the chemical composition of the comet’s surface and atmosphere or coma.

Focus on the planets

Mercury waits until midmonth to make an appearance, when it pops above the eastern horizon at dawn. Saturn is positioned far above. Mercury had an earthly visitor this month as the Messenger spacecraft flew past on Oct. 6 and is expected to send hundreds of images back to Earth.

Venus is low in the southwest shortly after sunset. Look for a close pairing with the crescent moon on Oct. 31.

Mars has vanished into the glow of sunset and it will be several months before the Red Planet reappears.

Jupiter is high in the south at dusk far to the upper left of Venus. Jupiter is slowly moving eastward toward the Teapot asterism of Sagittarius. On Oct. 11, its moon Ganymede will appear from behind Jupiter to take a two-hour journey across the face of the planet before disappearing from view.

Saturn rises in the east about two hours before sunrise as the month opens. Viewers hoping for a glimpse of Saturn’s ring system will be disappointed as they are as close to edge-on as they have been in the past 12 years.

Neptune, a blue-gray disk in Capricornus and Uranus, a blue-green disk in Aquarius, rise high in the south at 9 p.m. and 11 p.m., respectively. Consult the finder’s chart in the September issue of Sky & Telescope to help locate them.

October events

14 Full moon, 4:03 p.m. The full moon of October is known as the Hunter’s Moon. American Indians also called it the Moon of the Falling Leaves and the Dying Grass Moon.

17 The moon is at perigee or closest approach to Earth today. The moon slips past the Pleiades star cluster tonight in some cases briefly covering some of its stars.

21 Moon in last quarter, 7:56 a.m. This is the peak night for the Orionid meteor that may produce up to 10 fast meteors an hour that often leave persistent trains.

23 The sun enters the astrological sign of Scorpio but is still in Virgo astronomically.

25 Look for a close pairing of Venus and Antares in the southwest about an hour after sunset.

26 Mercury and the moon are visible by binoculars low in the east at first light.

28 New moon, 7:10 p.m.

30 The sun enters Libra on the ecliptic but astrologically is still in Scorpio.

31 The thin crescent moon, Antares, and Venus are closely grouped in the southwest 45 minutes after sunset. Halloween, a cross-quarter day marking the midpoint between the autumn equinox and winter solstice. Sunrise, 7:12 a.m., sunset, 5:26 p.m.