SKYTHIS MONTH
Visible to the naked eye Visible with binoculars Visible with a telescope
MARTIN RATCLIFFE and ALISTER LING describe the
solar system’s changing landscape as it appears in Earth’s sky.
January 2018: Totality over America
On October 8, 2014, the Full Moon passed into Earth’s umbral shadow and created this stunning total lunar eclipse. On January 31, observers across more than half the globe can witness a similar event. DAMIAN PEACH
A
ll of January’s naked-eye planets congregate in the morning sky. Mars and Jupiter lead the way, and they provide the month’s planetary highlight when they pass within 1° of each other during the New Year’s first week. The pair makes a stunning backdrop for the Moon when it slides by a few days later. Mercury and Saturn also shine brightly from their positions lower in the predawn sky. But the Moon deserves top billing in January’s sky show. On the 31st, our satellite dives completely into Earth’s umbral shadow, bringing a total lunar eclipse to viewers in much of North America, the Pacific Ocean, Asia, and Australia. This is the first total eclipse since September 2015.
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A ST R O N O M Y • JA N UARY 2018
From North America, the eclipse occurs before dawn and delivers better views to those who live farther west. East of a line that runs from the Ohio-Indiana border to New Orleans, the eclipse starts after the onset of twilight and the Moon sets before totality begins. The Full Moon enters Earth’s umbral shadow at 6:48 a.m. EST (3:48 a.m. PST). Within 10 minutes, the lunar orb looks like a giant sugar cookie with a bite taken out of it. The geometry of the Sun, the Moon, and Earth drives itself home during lunar eclipses in twilight. With the Sun just below the eastern horizon before dawn and the eclipsed Moon hanging low in the west, you can almost feel the giant rock you’re standing
on casting its shadow all the way to its only natural satellite. Those in the continent’s western two-thirds can view at least some of totality, which gets underway at 6:52 a.m. CST (4:52 a.m. PST). Totality lasts 76 minutes and can be seen in its entirety west of a line that runs from central North Dakota to New Mexico. The eclipsed Moon hangs among the stars of Cancer the Crab with the Beehive star cluster (M44) 4° to its northwest. Observers in Northern California, Oregon, and Washington get to witness the concluding partial phases, which wrap up at 7:11 a.m. PST. Fortunately, we don’t have long to wait for the next total lunar eclipse. Earth will cast its shadow on the Moon on July 27 (though this time the eclipse won’t be visible from North America), and again the night of January 20/21, 2019. The eclipse isn’t Luna’s only distinction during January.
Totality occurs at the month’s second Full Moon, so it also earns recognition as a Blue Moon. Our satellite reaches its first Full phase on New Year’s Night. This is the closest Full Moon of 2018, so it is also the biggest (33.5' across), and many people will feel compelled to label it a “Super Moon.” Although no planet rises to the level of “super” this month, most will reward your viewing efforts. The evening sky offers the two outermost and dimmest members of the solar system’s family. Despite their faintness, both Uranus and Neptune are within range of binoculars. Neptune lies lower and should be your first target. In early January, the ice giant stands 30° above the southwestern horizon at the end of twilight. Neptune glows at magnitude 7.9 among the background stars of Aquarius. You can find it near
A great view of totality LEO
Regulus
Eclipsed Moon Pollux
Alphard
HYDR A
CANCER
Castor GEMINI
10° January 31, 5:30 A.M. PST Looking west Viewers in western North America won’t want to miss the spectacular total lunar eclipse in January 31’s predawn sky. ALL ILLUSTRATIONS: ASTRONOMY: ROEN KELLY