The Hunter’s Moon Wades through Water Constellations, Jupiter jumps Mercury, and Uranus Looks its Best!

The phenomenon that is the zodiacal light is best seen during twilight after sunset in spring and before sunrise in autumn. This otherworldly photo was taken at Teide National Park on Tenerife, in the Canary Islands. (Photo: StarryEarth/Flickr)

Orionids Meteor Shower

We’ve now entered meteor shower season! Over the next few months, we’ll experience a wave of several showers. The excellent Orionids Meteor Shower, which is derived from material dropped by repeated past passages of Comet Halley, peaked in the hours after midnight (in your local time zone) this morning. At that time, the sky over your head will be plowing forward through the densest region of the particle field, generating up to 25 meteors per hour. The meteors will continue to appear for several more nights.

(Above: Tunc Tezel of Turkey created this composite image of the Orionids Meteor Shower from a sequence of tripod-mounted camera images. NASA APOD for October 23, 2006)

The meteors can appear anywhere in the sky, but true Orionids will be travelling in a direction away from a location (the radiant) a fist’s diameter to the upper left of the bright red star Betelgeuse in the constellation of Orion. Although not too numerous, Orionids are known for being bright and fast-moving. You can watch for meteors in the evening, too — but many of them will be hidden behind the Earth’s horizon.

To see the most meteors, find a wide-open dark location, preferably away from light polluted skies, and just look up with your unaided eyes. Binoculars and telescopes are not useful for meteors — their field of view are too narrow. If the peak night is cloudy, several nights on either side will be almost as good. Happy hunting!

The Moon and Planets

The moon will continue to gleam in the evening sky this week as it transitions through the middle of its monthly cycle. Between tonight and Wednesday, the waxing gibbous moon will pass through the dime water constellations of Aquarius (the Water-bearer), Pisces (the Fishes), and Cetus (the Whale).

The full moon of October, traditionally called the Hunter’s Moon, Blood Moon, or Sanguine Moon, will occur around mid-day on Wednesday. Since it’s opposite the sun at that time, the moon will rise at sunset and set at sunrise.

When the moon is full, bright ray features may be seen radiating from the most recent craters on the lunar near side. The biggest ray system surrounds the prominent crater Tycho, which is located in the southwestern region of the moon’s face, about where the “Lady in the Moon” would have her pendant. (Note that east and west are reversed on the moon). The bright lines radiating from the crater are reflective crystalline rocks excavated when Tycho was formed. They extend up to 1,500 km from the crater!

Mare Fecunditatis, Latin for “Sea of Fertility”, is a large dark mare in the eastern equatorial region of the moon, south of the very round Mare Crisium “Sea of Crises”. Near the centre of Mare Fecunditatis sit a pair of small deep craters named Messier. Parallel bright rays extend into the bright lunar highlands rocks to the west. They resemble a comet in binoculars or telescopes. The rays, approximately 120 km long, are consistent with an extremely low angle impact that arrived from the east at 1.7 km/second. That’s more than 6,000 km per hour — five times faster than a rifle bullet!

(Above: The major features on the full moon include dark maria regions and ray systems emanating from recent craters, such as Tycho.)

After Wednesday, the moon will wane and rise later — lingering for a little while into the morning daytime sky. Overnight on Friday, the waning gibbous moon will approach and then pass through the Hyades star cluster, the stars that form the triangular face of Taurus (the Bull). The moon will enter the cluster at approximately 3 am Eastern Time on Saturday morning. By sunrise in the Eastern time zone, the moon will be in the centre of the triangle. Observers in western North America will be able to see the moon pass less than a finger’s width above Aldebaran, Taurus’ brightest star at about 7 am Pacific Time. This pairing of the bright star and the moon is also an opportunity to look for Aldebaran in daylight using the nearby moon as a guide.

The moon will end the coming weekend brushing the horns of Taurus, above the bright winter constellation (Oh, no — not Winter!) of Orion (the Hunter).

Mercury will still be visible this week, but it will be tough to see it from the Northern Hemisphere because it will be barely above the west-southwestern horizon after sunset. The elusive planet will set at about 7 pm local time — 45 minutes after the sun. Because Mercury is on the far side of the sun right now, its appearance in a telescope will be a nearly fully illuminated disk. (For eye safety, be sure to wait until the sun has vanished completely before using binoculars or a telescope on Mercury.)

For an added bonus, and some help to find Mercury, the bright planet Jupiter will pass near Mercury later this week. Tonight, Jupiter will be less than a fist’s diameter to Mercury’s upper left. On Saturday, October 27, Jupiter will sit only 3.5 finger widths directly above Mercury. The two planets will be slightly closer together on Sunday evening, and then start drawing apart next week. Jupiter will set in the west-southwest before 7:30 pm local time. After this week, we’ll have to wait until next May before the mighty planet will return to the evening sky.

(Above: Mercury will sit below Jupiter in the western evening sky on Sunday, October 27, as shown here at 6:45 pm local time.)

Reddish Mars and dimmer, yellow-tinted Saturn will remain visible in the southern evening sky this week. As soon as the sky becomes dark enough to reveal them, both planets will be located about two fist diameters above the horizon, with Mars located 35° (three and a half fist diameters) to the left of Saturn. Mars will set in the west at about 1:15 am local time. It’s still well worth looking at, even in a small telescope. Try to see a small white oval near the top of its disk. That’s the southern polar cap (but inverted by your telescope’s optics)!

Saturn will set before 10 pm local time. Once the sky darkens, even a small telescope should be able to show you some of Saturn’s larger moons, especially its largest satellite, Titan. Using a clock’s dial analogy, Titan will move counter-clockwise over the course of this week — starting from a position at 9 o’clock (to the left of Saturn) tonight, and ending next Sunday at 4 o’clock (to the lower right of Saturn). (Remember that your telescope might flip and/or invert the view. Use the moon to find out how your telescope changes things and keep a note of it, since that will always be the case.)

(Above: Mars and Saturn remain excellent targets for evening observing this week, as shown here at 7:15 pm local time.)

This autumn presents an ideal time to peruse the ice giant planets Uranus and Neptune because they will be conveniently placed for evening observing and also bigger and brighter than normal because Earth is roughly between them and the sun right now, minimizing our distance from those planets.

Distant Neptune continues to be visible from evening until about 3 am local time. Using a decent quality telescope you can see the very blue, magnitude 7.8 planet among the dim stars of Aquarius (the Water-bearer) — sitting roughly midway between the modestly bright star Phi (φ) Aquarii and the brighter star Hydor (Lambda Aquarii). Neptune will highest in the sky (and best viewing conditions) at about 10 pm local time. The bright moonlight will make seeing the planet harder this week.

On Tuesday, the blue-green planet Uranus will reach opposition. At that time, it will be visible all night and at its peak brightness (magnitude 5.7) and size for this year. You can see it without optical aid under very dark skies, but binoculars and telescopes will work better. After mid-evening, Uranus will be high enough in the eastern sky to see it clearly. Uranus is so far from Earth all the time that its appearance at opposition is little better than it is on evenings within a month of opposition. The planet will be 2.8 trillion km from us this week. Its reflected sunlight will require more than 2.5 hours to reach our eyes on Earth!

(Above: On October 23, the Earth will pass between Uranus and the sun, causing that planet to appear at its brightest and largest for the year. The full moon will all but drown out Uranus.)

Uranus will be located about 3 finger widths to the left (east) of the modestly bright star Torcular (Omega Piscium). That star sits a generous palm’s width above the “V” where the two starry cords of Pisces (the Fishes) meet. The planet will be carried higher in the sky until 1 am local time.

Astronomy Skylights for this week (from October 21st, 2018) by Chris Vaughan. Keep looking up to enjoy the sky!



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