The month of October is filled with celestial delights and this guide shows how to spot some of the most promising night sky sights, starting with the moon:
Monday, Oct. 8 at 3:33 a.m. EDT: The last or third quarter moon rises around 11:15 p.m. and sets around 2:50 p.m. It is most easily seen just after sunrise in the southern sky.
Monday, Oct. 15, 8:02 a.m. EDT: The moon is not visible on the date of new moon because it is too close to the sun, but can be seen low in the east as a narrow crescent a morning or two before, just before sunrise. It is visible low in the west an evening or two after new moon.
Sunday, Oct. 21, 11:32 p.m. EDT: The first quarter moon rises around 2:00 p.m. and sets around 12:20 a.m. It dominates the evening sky.
Monday, Oct. 29, 3:49 p.m. EDT: The full moon of October is called the hunter's moon. In Algonquian it is called the white frost on grass moon. Other names are travel moon, dying grass moon, blood moon and harvest moon. In Hindi it is known as kojagiri or sharad purnima or lakshmi puja. Its Sinhala (Buddhist) name is vap. The full moon rises around sunset and sets around sunrise, the only night in the month when the moon is in the sky all night long. The rest of the month, the moon spends at least some time in the daytime sky.
Wednesday, Oct. 3, 4 a.m.: Venus will pass just south of the first magnitude star Regulus this morning. Venus now looks like a tiny waning gibbous moon, 72% illuminated, within the same telescope field as Regulus.
Thursday, Oct. 4, 11 p.m.: As the moon rises this evening, it is in the midst of the Pleiades and the Hyades, and is joined by the red giant star Aldebaran and the planet Jupiter. The same cast appears tomorrow at moonrise, but the moon has moved to the left of Jupiter. Observers in southern Australia will see the moon occult Jupiter.
Saturday, Oct. 13–27, pre-dawn: The faint glow of the zodiacal light will rise in the east ahead of the sun along the line of the ecliptic, as marked by Venus and Regulus. Don’t confuse it with the faint glow of the Milky Way in the southeast, marked by Sirius and Procyon.
Wednesday, Oct. 17, sunset: The 3-day-old crescent moon framed by the planets Mars and Mercury will be a challenge for northern observers unless they have a very low southwestern horizon. Observers in the southern hemisphere will have a much better view.
Sunday, Oct. 21, midnight–dawn: The Orionids are remnants of Halley’s Comet scattered along its orbit, one of the finest meteor showers in the year. The meteors appear to radiate from a point just between Orion’s club and the Gemini twins’ feet, but may be seen anywhere in the sky.
Friday/Saturday, Oct. 26–27, sunset: The first view is from northeastern North America, where the angle of the ecliptic at sunset is very close to the horizon, making Mercury (and Mars) hard to see.
Friday/Saturday, Oct. 26–27, sunset: The second view is from southern Australia about 12 hours later, where the ecliptic is perpendicular to the horizon, making Mercury (and Mars) much easier to see.