The world is a far different place than when the Voyager 1 and 2 spacecraft blasted off into space to take a grand tour of the giant outer planets. Launched in 1977, today Voyager 1 is 11 billion miles from the sun and Voyager 2 is not far behind. It takes a signal, traveling at the speed of light, nearly 34 hours to reach Voyager 1.
The craft were launched to take advantage of a rare alignment of the four outer planets that occurs only once every 175 years. The alignment allowed the spacecraft to “slingshot” themselves from one planet to the next by taking advantage of the planet’s gravitational attraction.
Voyager 2 visited all four planets: Jupiter (1979), Saturn (1981), Uranus (1986) and Neptune (1989). Voyager 1 passed by Jupiter and Saturn. Their power sources were designed to have shut down years ago but now are expected to last another 10-20 years. Today both spacecraft are at the edge of the heliosphere, a giant bubble containing very high-energy charged particles that surrounds the Sun. Once they are through the heliosphere they will enter deep space and will roam the galaxy forever.
Focus on the planets
Mercury barely rises above the southwestern horizon about a half-hour after sunset. A good pair of binoculars will be needed to spot the elusive innermost planet.
Venus shines brightly in the east from about 3:30 a.m. to well into the dawn. Venus is a near neighbor of Regulus during October with a spectacular approach of less than a quarter of a degree between the pair on the 3rd of the month.
Mars rises in the southwest about an hour after sunset. The distant planet will appear as only a tiny orange dot even with a telescope. However, the proximity of Mars to Antares during the month will allow viewers to compare the orange hues of the planet and star.
Jupiter rises in the east shortly before midnight but is best viewed high in the south shortly before dawn when viewers with telescopes will be treated to the giant planet’s many surface features as well as the dance of its four major moons around and across the face of the planet.
Saturn rises in the west shortly after sunset but soon sinks into the sun’s glow marking its final appearance for the year.
Uranus is in the east near the Circlet of Pisces where its distinctive blue-green color may be spotted by binoculars.
Neptune is well up in the south around 9 p.m. where it may be spotted as a blue-gray disk. The Sky & Telescope website, skypub.com/urnep, will help to find these far distant planets.
1: Sunrise, 6:33 a.m.; sunset, 6:17 p.m.
3: Venus “grazes” Regulus during the early morning hours for the closest meeting of a planet with a 1st-magnitude star this year.
4: Jupiter, the moon and Aldebaran form a triangle in the east shortly before midnight.
5: The moon is at apogee or farthest distance from Earth. Note that Jupiter is to the immediate upper right of the moon.
8: Moon in last quarter, 3:33 a.m. The Draconid meteor shower peaks around this date, however, no activity is predicted for this year.
12: The crescent moon is just to the right of Venus an hour before sunrise with Regulus well to the upper right of the duo.
15: New moon, 8:02 a.m.
17: The moon is at perigee, or closest approach to Earth for the month. The thin crescent moon is to the lower right of both Mars and Antares in the southwest just after sunset.
21: Peak night for the Orionid meteor shower. The moon sets around 11 p.m. as the peak viewing hours approach so viewers can expect activity of up to 25 per hour of fast, bright meteors that often leave persistent trains.
22: The Earth was created on this date in 4004 BC, according to Archbishop James Ussher in 1650. Moon in first quarter, 11:33 p.m.
23: The sun enters the astrological sign of Scorpio but astronomically is still in Virgo.
25: Saturn is in conjunction with the sun, i.e. behind it as seen from Earth, and passes into the morning sky.
29: Full moon, 3:49 p.m. The full moon of October is the Hunter’s Moon, also sometimes called the Dying Moon, as the leaves and vegetation die back for the winter.
30: The sun enters Libra on the ecliptic but astrologically still resides in Scorpio.
31: Halloween, a cross-quarter day that marks the midpoint between the fall equinox and winter solstice. Sunrise, 7:12 a.m.; sunset, 5:26 p.m.