October’s darkening skies provide a backdrop for planetary maneuvers and the unending stream of stars across the celestial stage.
As Venus holds its position above the sunset horizon, Saturn, followed by much brighter Jupiter, heads westward with the stars of Capricornus. On October 9, red Antares, the heart of Scorpius, will be left of Venus and a waxing crescent moon in the sun’s afterglow. As Antares exits the sky, it draws closer to Venus and glimmers directly below the planet on October 16. On October 14, Jupiter and Saturn come out above a gibbous moon.
On October 17, Mars passes behind the sun and officially takes up residence in the morning sky—which is where you’ll also find Saturn, Jupiter, and Venus next year.
Facing south, you’ll see—perhaps with help from a star chart—the relatively dim fall constellations. From west to east, the main ones are chevron-shaped Capricornus, the sea goat; scraggly Aquarius, the water bearer; and two-tailed Pisces, the fishes. Fairly high in the southeast at nightfall is the Great Square of Pegasus. Below the Great Square is a pretty ring of stars known as the Circlet of Pisces.
October’s full moon arrives the morning of October 20. To see it, get outside by about 40 minutes before sunrise or it will have set in the west. If you’re not a morning person, enjoy the moonrise on the evening of either October 19 or 20.
October closes with Halloween, an astronomically-based Celtic holiday that was one of four “cross-quarter” days falling midway between an equinox and a solstice. On that night, evil spirits cooped up since May Day were released to wreak havoc on humankind. People left out food to appease the spirits and lit candles in gourds to ward them off; these were the forerunners of trick-or-treating and jack-o’-lanterns.
October 6—New Moon
The Moon is located on the same side of the Earth as the Sun and is not visible in the night sky. This is the best time of the month to observe faint objects like galaxies and star clusters because there is no moonlight to interfere.
October 12—Third Quarter Moon
This phase occurs when the Moon is three-quarters of the way through its orbit around the Earth.
October 20—Full Moon
The Moon is located on the opposite side of the Earth as the Sun and the side we see is fully illuminated.
October 28—First Quarter Moon
The Moon is one-quarter of its way through its orbit around the Earth, which makes half the Moon illuminated and half dark from our perspective. This is the best time of the month to see the Moon’s surface features like craters and mountains through binoculars or a telescope.