My first Magazine Sky & Telescope - 01.2019

January’s Lunar Blackout Harpalus Plato– Eclipse-Timing Predictions EXIT (UT) Grimaldi 3:36 Harpalus 5:49 Billy 3:40 Aristarchus 5:54 Kepler 3:48 Plato 5:57 Campanus 3:49 Grimaldi 5:58 Aristarchus 3:50 Pico 5:59 Tycho 3:56 Kepler 6:02 Copernicus 3:57 Aristoteles 6:04 Birt 3:57 Billy 6:05 Pytheas 4:00 Pytheas 6:05 Timocharis 4:06 Timocharis 6:05 Harpalus 4:08 Eudoxus 6:07 Manilius 4:13 Copernicus 6:09 Pico 4:15 Campanus 6:17 Dionysius 4:15 Manilius 6:19 Plato 4:18 Menelaus 6:22 Menelaus 4:17 Birt 6:24 Plinius 4:21 Plinius 6:25 Censorinus 4:21 Tycho 6:27 Goclenius 4:24 Dionysius 6:28 Eudoxus 4:25 Proclus 6:32 Aristoteles 4:27 Censorinus 6:35 Taruntius 4:28 Taruntius 6:37 Langrenus 4:29 Goclenius 6:42 Proclus 4:31 Langrenus 6:46 Aristarchus Timocharis – Pytheas– Kepler– Mid- eclipse 5:12 UT Total eclipse begins 4:41 UT –Billy –Birt Campanus –Tycho p KEEPING WATCH This photo identiies 24 well-deined craters and spots that stand out during a total lunar eclipse. North is up, so Earth’s shadow will move in and recede from left to right. Moon’s path tic UMBRA PENUMBR South JA N UA RY 2 019 • SK Y & TELESCOPE A Moon enters penumbra (unobservable) 2:35 UT Partial eclipse begins 3:34 UT Eclip 20 Taruntius– totality) when compared with the rest of the lunar disk. But once more than half of the Moon is immersed in shadow, the contrast becomes less extreme and details of the disk within the umbra slowly come into view. Because sunlight is refracted and scattered by atmospheric gases around the limb of Earth, some of it gets redirected into the dark shadow cone and onto the Moon. Red predominates in this light for the same reason that sunrises and sunsets also appear red. Looking skyward from the lunar surface, our hypothetical astronaut would see the disk of Earth surrounded by a thin, brilliant ring of red — the combined light of all the sunrises and sunsets occurring at that moment worldwide. When the Moon moves into total eclipse, that red-hued light suddenly becomes the only illumination on the lunar landscape. And that’s the reason that the Moon tends to look like a ruddy ball once it’s completely within the umbra. Local Circumstances of the Total Lunar Total eclipse ends 5:44 UT –Plinius Langrenus Censorinus Goclenius– –Grimaldi North Partial eclipse ends 6:51 UT Proclus –Copernicus Dionysius– q DARK PASSAGE The Moon moves through the northern half of Earth’s shadow on the night of January 20–21. Universal Times are given below for the event’s key stages, though local times are used in the table. Moon leaves penumbra (unobservable) 7:50 UT Menelaus Manilius ENTRANCE (UT) –Aristoteles – udoxus HST AKST PST Penumbra ﬁ rst visible? — 6:10 p.m. 7:10 p.m. Partial eclipse begins — 6:34 p.m. 7:34 p.m. Total eclipse begins 6:41 p.m. 7:41 p.m. 8:41 p.m. Middle of totality 7:12 p.m. 8:12 p.m. 9:12 p.m. Total eclipse ends 7:44 p.m. 8:44 p.m. 9:44 p.m. Partial eclipse ends 8:51 p.m. 9:51 p.m. 10:51 p.m. Penumbra last visible? 9:15 p.m. 10:15 p.m. 11:15 p.m.

My first Magazine Sky & Telescope - 01.2019 | Page 22