The Full Wolf Supermoon Kicks off the Year, Meteors under Moonlight, Happy Perihelion, and Mars and Jupiter Kiss at Dawn!
(Rick Foster of Markham took this image of the bright star Aldebaran in Taurus the Bull just shy of being occulted by the first quarter moon in late evening on March 4, 2017. Aldebaran and the moon meet frequently. On Saturday night, December 30, 2017, the moon fully occulted the star.)
Happy Perihelion! On Wednesday, January 3 at 1 pm Eastern Time, the Earth reaches the point in our orbit when we are closest to the sun (also known as perihelion) for the entire year! We’ll be only 147.1 million km away from it. Do you feel warmer? You shouldn’t — our temperature is controlled by the height of the sun in the sky and the lengths of our days, and not by our distance from it.
Quadrantid Meteor Shower
The annual Quadrantid Meteor Shower is underway. It peaks before dawn on Thursday, January 4, and you can continue to watch for fewer of them until the shower tapers off around January 10. The source material for these meteors is an asteroid designated 2003 EH. The average hourly rate is about 25, but during the short, intense peak period, it’s possible to see more than 100 per hour! Unfortunately, bright moonlight from moon’s waning gibbous phase on the peak night will reduce the number of meteors we see.
(Above: The radiant for the Quadrantid Meteor Shower is located north of Bootes. The meteors can appear anywhere in the sky, but will be travelling away from the radiant. A very bright moon will wash out all but the brightest Quadrantids this year.)
The Quadrantid Meteor Shower is named for a former constellation called the Mural Quadrant, which was located between Hercules and the tip of the Big Dipper. The meteors can appear anywhere, but true Quadrantids will appear to be travelling away from a location in the northern sky near the Big Dipper (their radiant point). This shower favours Northern Hemisphere observers worldwide. I’ll post a sky chart showing the radiant on Tumblr here.
The Moon and Planets
The January full moon phase, known as the Wolf Moon, Old Moon, or Moon after Yule, arrives at 9:24 pm Eastern Time on Monday evening. Like every full moon, this one rises at sunset and sets at sunrise. But the upright position of the ecliptic on winter nights causes January moons to climb much higher in the night sky and cast shadows similar to the summer sun. This full moon also occurs less than five hours after perigee, the point in the moon’s orbit when it is closest to Earth, making this full moon the largest and brightest supermoon of 2018. A month from now on January 31, the moon will also be “super” and pass through the Earth’s shadow for a morning total lunar eclipse.
After Monday, the moon will wane, and its continuous eastward motion will carry it through Gemini (the Twins) and Cancer (the Crab). From Thursday evening through Friday morning, the waning gibbous moon will move towards, and then pass very close to, the bright star Regulus in Leo (the Lion) — so close that the pair will be visible together in a telescope at low magnification. In the GTA, closest approach happens at 2:38 am Eastern time. For observers in Alaska, the eastern tip of Russia, northern Canada, Greenland, Svalbard, Iceland, most of Europe, and northwestern Africa, the moon will cross in front of (or occult) Regulus. To find out when, simply convert 2:38 am Eastern Time to your own time zone.
(Above: Overnight from Thursday into Friday, January 5, the moon will pass near the bright star Regulus in Leo. The sky is shown here at 3 am Eastern Time. Parts of the world will see the moon occult the star.)
The distant ice giants are the only planets left in the evening sky — until Jupiter starts rising before midnight in early March. Blue-green Uranus is in the southern sky after dusk, midway between the two chains of stars that form the dim constellation of Pisces (the Fishes). Look for it about two finger widths higher than the visible stars Omicron (o) and Mu (μ) Piscium, which bracket it. Because it sets about 1:30 am local time, you can look for it in binoculars until about midnight. Tiny blue Neptune, which can only be observed in a telescope, is already in the lower half of the southwestern sky after dark. It’s about half a finger’s width to the lower left of the medium-bright star Hydor in Aquarius (the Water-Bearer), and it sets about 10 pm local time.
(Above: The southern evening sky, shown for 7:30 pm local time on New Year’s Day, features Uranus and Neptune, and the winter treats of Orion and Taurus.)
As has been the case for several weeks, the planet party is in the pre-dawn sky! Jupiter is the very bright object glowing in the eastern sky between about 3:30 am local time and dawn, when it’s well above the southeastern horizon. Once again this week, the bright double star Zubenelgenubi in Libra (the Scales) is sitting only a finger’s width to the right of Jupiter.
(Above: In the east-southeastern pre-dawn sky of January 6 and 7, 2018, Mars’ eastward motion (red line) will carry it very close to Jupiter. The bright and easy double star Zebenelgenubi sits above the planets. The sky is shown for 3:45 am local time, but the pairing should be visible until the sky begins to lighten before sunrise.)
(Above: A simulated small telescope view of Mars and Jupiter at closest approach. Jupiter will appear MANY times brighter than reddish Mars.)
On the coming weekend, we get a special treat! For weeks, the eastward orbital motion of red-tinted Mars has been carrying it towards Jupiter. And this weekend, they finally kiss! On both Saturday and Sunday morning, January 6 and 7, observers in the Americas will see the two planets separated by about one-third of a degree (less than a full moon’s diameter). In a backyard telescope, the planets, plus Jupiter’s four Galilean moons, will appear together within the field of view of a low power eyepiece! It will be a nice binocular sight, too. I’ll post a diagram here.
(Above: Mercury reaches its greatest angle west of the sun on January 1, 2018, shown here looking southeast at 7 am local time. After Monday, Mercury will take about a week to drop into the pre-dawn brightness.)
This is the final week to see Mercury with your unaided eyes or binoculars during its latest appearance. On Monday, the normally elusive planet will reach its greatest angle west of the sun. It will be visible low in the eastern sky for about 45 minutes before sunrise. The best times to look for it fall between 6:30 and 7:15 am local time. To unaided eyes, Mercury will resemble a medium bright “star”. In a telescope the planet will exhibit a waxing gibbous phase.
Keep looking up to enjoy the sky! I love getting questions so, if you have any, send me a note.
Astronomy Skylights for this week (from December 31st, 2017) by Chris Vaughan.