If the weather holds, October is a lovely month for stargazing. The Milky Way still lingers in the west along with stars that were prominent in the northern summer. The autumn stars dominate overhead, and the northern winter stars are starting to poke above the eastern horizon. Best of all, you can get in a good night of stargazing without staying up too late. Jupiter and Saturn remain visible, Venus and Mercury make an appearance, Uranus reaches opposition, and Mars returns! Add in a couple of meteor showers and you’re in for a good month. Here’s what to see in the night sky this month…
3 Oct. Jupiter and the waxing crescent Moon lie about 1.5o apart in the southwestern sky this evening just after sunset. Look also for the red-orange star Antares about a fist-width to the south and west. It’s been a good show this year, especially for southern stargazers, but Jupiter is shrinking and growing fainter and headed back towards the sun. At magnitude -1.9 by month’s end, the planet still outshines any star and remains big enough to reveal detail in a telescope in steady sky. The planet remains in the constellation Ophiuchus and moves a little eastward against the background stars each day. It sets about 2.5 hours after the sun by the end of the month.
4 Oct. The Moon, Jupiter, Saturn and Antares follow a gentle arc about 35o long in the southwestern sky after sunset.
5 Oct. First Quarter Moon, 16:47 UT
5 Oct. The first quarter Moon lies about 2o from the planet Saturn in eastern Sagittarius, near the handle of the ‘Teapot’.
7 Oct. Saturn reaches eastern quadrature at a position 90o from the Sun. At this time, and for the next few weeks, the sun’s light casts particularly long and dramatic shadows that make the ringed planet look almost ‘three dimensional’ on nights of good seeing. The rings are tilted about 25o to our point of view making for excellent and dramatic viewing. Saturn dims to magnitude +0.6 by month’s end and sets by about 10 p.m. Like Jupiter, Saturn is on its way out for the year, so see it while you can!
8 Oct. The Draconid meteor shower peaks over the next few days. This meteor shower occurs each year when the Earth passes through a stream of debris left from periodic Comet Giacobini-Zinner. While it’s usually a spartan meteor shower, with just a handful of meteors visible each hour, the Draconids have flared up from time to time. In 1933 and 1946, observers reported thousands of meteors per hour, so this modest shower became a meteor storm. There was also a good show in 1988. There’s no word of a flare up this year, but if you’re out stargazing, take a look. You never know.
13 Oct. Full Moon, 21:08 UT. This full Moon will be the ‘smallest’ of 2019, appearing about 14% smaller than a ‘super moon’.
17 Oct. If you can’t wait for the stars of northern winter to arrive, then wake up well before sunrise to behold Orion, Canis Major, Taurus, Auriga, and Gemini lined up from overhead down to the south. Today, the waning gibbous Moon joins the show near the star Aldebaran in the constellation Taurus.
19 Oct. Mercury reaches greatest eastern elongation about 25o east of the Sun. However, the planet, despite reaching magnitude 0.0 this month, is low over the western horizon in the twilight after sunset. A pair of binoculars will help you see this speedy little world.
21 Oct. Last Quarter Moon, 12:39 UT
21-22 Oct. Look for the Orionid meteor shower in the early morning hours. One of the finest of all meteor showers, the Orionids present perhaps 20-40 fast-moving meteors per hour in dark sky. The radiant of the Orionids is near the club of Orion, but you can see the meteors anywhere in the sky in both hemispheres. Just look up anywhere and start watching. Early morning, from 3 a.m. local time through dawn, is the best time to observe the shower. This year, the light from the last-quarter Moon may wash out some of the fainter meteors, especially after midnight. Like the Aquariid meteors in May, the Orionid meteors are bits of Comet Halley that hit the upper atmosphere as the Earth passes through the debris field of the comet.
26 Oct. Set your alarm clock to wake early and go see a very slender crescent Moon, the star Porrima, and the planet Mars low over the eastern horizon before sunrise. After some time lost in the sun’s glare, Mars makes its return to the sky this month. The planet is tiny, not much bigger than Uranus in a telescope, and relatively faint at magnitude +1.8. Binoculars will help you take it all in. Mars will rise a little earlier each day for the rest of the year and into 2020. It next reaches opposition nearly a year from now on October 13, 2020.
28 Oct. New Moon, 03:38 UT
28 Oct. The planet Uranus reaches opposition in the constellation Aries as it rises opposite the Sun. The planet reaches magnitude 5.7 and has a disk about 3.7″ across near opposition. Wait until the planet gets well above the horizon for the best view. The image above shows you the location of Uranus in late October 2019. The planet is well north of the celestial equator, so northern observers can wait for nights of steady seeing to observe the planet at high magnification. The planet is visible in the evening and late night hours from October through the end of 2019 and into 2020.
29 Oct. A ‘reborn’ Moon, very slender and low over the western horizon after sunset, is joined by brilliant Venus. Bring binoculars to pull the pair out of the twilight glare. The beautiful planet remains low in the west this month and next, but at magnitude -3.9 it is plenty bright enough to see if you have a clear view of the western horizon. In a telescope, the planet is nearly fully lit, but small, just 10” across.