SkyEye

The Calendar

A dramatic annular solar eclipse takes place mid-month, followed by a partial lunar eclipse two weeks later. Venus continues to climb higher above the eastern horizon at dawn and is best observed from northern latitudes.

The Solar System

The word planet is derived from the Greek word for 'wanderer'. Unlike the background stars, planets seem to move around the sky, keeping mostly to a narrow track called the ecliptic, the path of the Sun across the stars. Dwarf planets and small solar-system bodies, including comets, are not so constrained, often moving far above or below the ecliptic.

Sun Virgo → Libra

Mercury Leo → Virgo → Libra

Visible in the west after sunset, Mercury brightens as it heads toward the horizon, disappearing before superior conjunction on 20 October. The lunar occultation which takes place six days earlier happens during daylight hours. After conjunction, Mercury takes its place in the morning sky, with a close encounter with Mars occurring on 29 October. Although dimming now that superior conjunction has passed, it is still brighter than the red planet just 0.3° away.

Venus Leo

Venus continues to climb higher above the eastern horizon. At magnitude −4.5, it is impossible to miss but is best seen from northern and equatorial latitudes. The morning star is 2.3° south of first-magnitude Regulus on 9 October. It reaches theoretical dichotomy on 22 October and greatest elongation west the following day. Venus passes through its ascending node on 25 October, returning to the north side of the ecliptic plane.

Earth and Moon

Two eclipses take place in October, with an annular solar eclipse coming first on 14 October, followed by a partial lunar eclipse two weeks later. Moonlight should not spoil viewing the Draconid meteor shower in early October, nor the Orionids in the latter half of the month. The nearly New Moon occults both Mercury and Mars but neither event will be visible during evening hours. The waning gibbous Moon occults the Pleiades twice this month, on 3 October and again on 30 October. The first-magnitude star Antares also disappears behind the Moon's disk on 18 October. The Moon also skirts past first-magnitude Spica on 3 October and Pollux four days later.

Mars Virgo → Libra

Second-magnitude Mars is very low in the west at sunset but may still be visible from southern hemisphere vantage points, at least early in the month. The red planet is 2.4° north of Spica, the brightest star of Virgo on the third day of the month. The lunar occultation on 15 October, however, may be too close to the Sun to be observable. Kang or κ Virginis, a fourth-magnitude K-type giant star, is found 2.7° north of Mars 19 October and Mercury is in close attendance on 29 October.

Jupiter Aries

With opposition happening early next month, Jupiter rises during evening twilight and is visible for the rest of the night. Shining at magnitude −2.8, the gas giant is twice visited by the Moon, appearing just over 3° away from our satellite on both 2 October and 29 October.

Saturn Aquarius

The ringed planet is visible in the evening, already well aloft by the time the skies darken and setting just after midnight. It shines at magnitude +0.5, the brightest star-like object in the constellation of Aquarius. The waxing gibbous Moon is just 2.8° south of the ringed planet on 24 October.

Uranus Aries

As Uranus slowly approaches opposition next month, it is passed by the waning gibbous Moon twice, on 2 October and again on 30 October when the two bodies are less than 3° apart. However, the glare of the nearly full Moon will wipe out any chance of seeing sixth-magnitude Uranus with the naked eye on these dates; choose an evening in the middle of the month to seek out this distant world.

Neptune Pisces

Now past opposition, Neptune is already above the horizon when the sky darkens in the evening. The waxing gibbous Moon pays a visit on 26 October when the two bodies are only 1.5° apart but the glare of our satellite may make observing nearby eighth-magnitude Neptune problematic, even with a telescope.