An Evening Moon, Asteroid Juno Jumps Out, Leonid Meteors at Maximum, and we Tour the Lucky Water-Bearer!
The Moon and Planets
This is the best week of the lunar month to pull out your binoculars and telescopes to look at the moon. Each evening, the moon will wax fuller and shift farther from the sun. While this is happening, the sun will be slowly rising over the moon’s surface. Its low-angled sunlight will illuminate peaks and crater edges while casting deep black shadows between them. It also reveals subtle topographic features, such as ridges and cracks on crater floors, that are otherwise invisible. New sections of the moon are highlighted every night. And, the moon will be visible right after dinner — how convenient!
Tonight (Sunday), the moon will appear as a beautiful crescent, shining like a Cheshire Cat’s smile over the western horizon after twilight. It will also be sitting a few finger widths to Saturn’s upper left. From Tuesday through Thursday, the moon will cross Capricornus (the Sea-Goat), landing just three finger widths from Mars on Thursday. The duo will set in the west at about midnight local time. (Observers in most of Antarctica, the Falkland Islands, and southern South America will see the moon pass in front of, i.e., occult, Mars at about 06:00 Greenwich Mean time.) The moon will also reach its First quarter phase on Thursday, when it will appear half-illuminated until it sets at midnight local time.
Turning now to the planets, very bright Venus is now shining in the morning pre-dawn eastern sky. This week, the planet will pass only a finger’s width to the lower left of the bright white star Spica in Virgo (the Maiden).
In the evening sky, Jupiter and Mercury are both located very low in the southwestern sky after sunset, embedded in twilight, leaving Saturn and Mars as your best planetary targets.
Even though it is gradually dimming as Earth pulls farther away from it, reddish Mars will continue to dominate the southern evening sky this week. Only the moon is brighter. Look for a bright, reddish, star-like object shining in the lower half of the southern sky after dusk. It’s among the stars of Aquarius (the Water-Bearer), which we’ll describe below. Mars will set in the west at about midnight local time.
Dimmer and yellowish Saturn is located five fist diameters to the lower right of Mars this week. After the sky has darkened, 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 4 o’clock (to the lower right of Saturn) tonight, and ending up next Sunday at 11 o’clock (to the upper left 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.)
Mars’ orbital motion has been carrying it eastward towards distant Neptune, which will be located about 1.5 fist diameters to the left (east) of Mars this week. The blue, ice giant planet is visible from dusk until just after 1 am local time. Using a decent quality telescope you can see the magnitude 7.8 planet sitting about two finger widths to the left of the modestly bright star Hydor (Lambda Aquarii). Neptune will highest in the southern sky (and best viewing conditions) at about 7:30 pm local time.
Blue-green Uranus (“YOU-ran-us”) is farther to the east than Neptune. It’s still close to 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. By mid-evening, Uranus will be high enough in the eastern sky to see it clearly. Look for it about 2 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 10:30 pm local time.
On Saturday, November 17, the major main belt asteroid Juno will reach opposition. At that time, Earth will be passing between the asteroid and the sun, minimizing our distance from Juno and causing it to appear at its brightest and largest for this year. The magnitude 7.45 object will be visible in binoculars and small telescopes all night long after it rises in the east at 6:30 pm local time. Juno will be positioned about equally distant from the bright stars Aldebaran in Taurus (the Bull) and Rigel in Orion (the Hunter). It will reach its highest position, about halfway up the southern sky, at midnight local time.
The Water Constellations — Aquarius the Water-Bearer
Evenings in late autumn feature a grouping of constellations over the southern horizon that share a common theme — the Sea. Collectively known as the water constellations, they aren’t very prominent, composed mainly of modest and dim stars, but this week’s moonless sky will offer an opportunity to see them better. Over the two weeks, I’ll talk about each of the watery constellations. This time, we’ll look at the sea-goat’s eastern neighbour.
Straddling the ecliptic, immediately to the east (left) of Capricornus is another zodiac constellation, Aquarius (the Water-bearer). This is one of the oldest recorded constellations, probably because of its place on the ecliptic / zodiac and because it re-appeared in the morning sky at the time of year that brought the return of desperately needed rains, and the flooding of the Nile, in ancient Egypt. It’s certainly not because of its stars. Its pattern is made from about 14 modestly-bright stars with visual magnitudes near the limit for suburban observers.
Aquarius spans an area that measures about 3.5 outstretched fist diameters wide by 2 diameters high. It is traditionally depicted as a kneeling figure, facing east, who is pouring water from a vessel. A crooked horizontal string of stars represent his right arm outstretched towards the west, his bowed head and shoulders, and his left hand, which bears the jug. This is the most easily seen part of the constellation. Descending from this line is a loose chain of stars representing the flowing water and another representing his torso and legs. In some stories, he’s Zeus pouring out the water of life upon the world. In others, the waters are those of the biblical flood, a story handed down from the Sumerians. As we’ll soon see, the stars of Aquarius are “lucky”.
By the time the sky has darkened enough to see it, Aquarius is due south, positioned about halfway between the southern horizon and the zenith. To help you find it, you can use the great square (or baseball diamond) of Pegasus, which sits much higher and to the left (east). With “home plate” as the bottom star, extend an imaginary line from third base to first base, and continue in the same direction by the same distance (about two fist diameters) to Aquarius’ highest and brightest star, Sadelmelik.
In a dark sky, up to 100 stars can be counted in the constellation, but only a few are easily seen near city lights. Try to spot the four stars that extend a wide palm’s width from Sadelmalik eastward to the left. One of the four stars sits a couple of finger widths below the line formed by the other three. At the eastern end of the four sits a modest star designated Eta Aquarii. The radiant of the springtime Eta Aquariid Meteor Shower is located close to this star.
Jumping 1.5 finger widths to the right of Eta brings us to a closely spaced double star that’s only 91 light-years away from us named Sadaltager “Luck of the merchant”. Two finger widths to the lower right of Sadaltager is the white star Sadachbia, which comes from the Arabic phrase sa’d al-akhbiya “lucky stars of the tents”. Then we hop higher again and westward to Sadelmelik, meaning “Lucky stars of the Kingdom”. Sadelmelik is a very mature, yellow supergiant star located about 520 light-years away. It’s a bit cooler than our Sun, but about 60 times larger in diameter, making it much more luminous.
Ten degrees (a fist’s diameter) to the lower right of Sadalmelik, at the water-bearer’s elbow, sits another of the constellation’s brighter stars, Sadalsuud “the luckiest of all of them all”. This is another yellow giant very similar to Sadelmelik and about as distant. Finally, Aquarius’ western hand is marked by a fainter blue-white star named Albali “Good Fortune of the Swallower”, which sits a fist’s width to the lower right of Sadalsuud. The rest of the constellation, descending in two crooked lines from the lucky stars, is fairly dim. About halfway along them, both lines take a jog to the left (east).
Aquarius contains only a few significant deep sky objects because it is situated away from the galactic plane, the Milky Way. The bright globular cluster designated Messier 2, which can be spotted in binoculars or small telescopes, is only 4 finger widths above Sadalsuud. It’s 37,000 light-years away! A planetary nebula named the Saturn Nebula (and also designated Caldwell 55) is located below Albali. At 650 light-years away, it’s among the closest such objects to us. Another planetary nebula, the Helix Nebula (or Caldwell 63), is near the bottom of the constellation. These two stellar corpses are visible in decent backyard telescopes. A second, dimmer globular cluster named Messier 72 sits below and between Albali and the Saturn Nebula.
Fittingly, Neptune has been situated in Aquarius since 2011. At present, it sits just to the left (east) of the fairly bright star named Hydor. Neptune won’t leave Aquarius until about 2022! Meanwhile, Mars is presently sitting near the western boundary of Aquarius. It will steadily travel eastward through the constellation until late December.
Leonids Meteor Shower
The Leonids Meteor Shower, which is derived from material dropped by repeated past passages of Comet 55P/Tempel-Tuttle, will peak on November 17/18. The maximum number of Leonids will appear before dawn local time, because that is when the sky overhead will be plowing directly into the cloud of particles that produce the shower.
The meteors can appear anywhere in a dark sky, but true Leonids will be travelling in a direction away from a location (the radiant) just above the stars that form the head of Leo (the Lion). You can watch for meteors in the evening, too — but many of them will be hidden from view below the Earth’s horizon. This week’s meagre moon will keep the sky darker — ideal for seeing fainter meteors.
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!
Astronomy Skylights for the week of November 11th, 2018 by Chris Vaughan.
Keep looking up, and enjoy the sky when you do. I love questions and requests — so, send me some!