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Home , 82 Aquarii, Elongation (astronomy)

By Martin Ratcliffe and Richard Talcott Sky Guide 2018

Mars shines brilliantly and looms large through telescopes this as it puts on its finest show since 2003. NASA/JPL-CALTECH contents 2 Jan. 2018 Eclipse of the Blue 3 Feb. 2018 Target these cool winter nights 4 March 2018 Catch at dusk 5 April 2018 The Lyre plays a sweet meteor song 6 May 2018 rules spring nights 7 June 2018 ’s rings on gorgeous display 8 July 2018 Red renaissance 9 Aug. 2018 Prime time for the Perseids 10 Sept. 2018 blazes in the evening twilight

11 Oct. 2018 An ice giant butts into the Ram Martin Ratcliffe provides professional 12 Nov. 2018 Juno at its best in 35 ­planetarium development for Sky-Skan, Inc. Richard Talcott is a senior editor of . 13 Dec. 2018 Making a swing past 14 2019 Preview Looking ahead to next year ... A supplement to Astronomy magazine

618364 2018 Jan. S M T W T F S Eclipse of the 2 3 4 5 6 7 9 10 11 12 13 14 15 17 18 19 20 Blue Moon 21 22 23 25 26 27 28 29 30 anuary features two third of the country experience Full , both of only the initial partial phases. which command our The Moon dips into Earth’s attention. The first dark umbral shadow at 1 Mercury is at great- comes New Year’s 6:48 a.m. EST (3:48 a.m. PST), est western elonga- night and arrives less than five but the Moon sets before total- tion (23°), 3 p.m. EST J hours after our satellite’s clos- ity begins at 7:52 a.m. EST 3 Quadrantid meteor shower peaks est approach to Earth during (4:52 a.m. PST). 2018. Its 33.5' apparent diam- Viewers in the central U.S. 5 The Moon passes 0.9° north of eter makes it the biggest Full see at least some of the total Regulus, 3 a.m. EST Moon of the year — a “Super phase. The Moon passes closest Moon” in popular parlance. to the center of our planet’s A total lunar eclipse always looks 6 passes 0.2° dramatic. Here, Greece’s Temple of south of Jupiter, The Full Moon before dawn shadow at 7:30 a.m. CST Poseidon stands before a February 11 p.m. EST January 31 is a touch smaller, (5:30 a.m. PST) and starts to 2008 eclipsed Moon. ANTHONY AYIOMAMITIS 9 Venus is in superior 33.2' across, and ranks as the exit the umbra at 8:08 a.m. CST , second largest of 2018. As the (6:08 a.m. PST). During the which wraps up at 7:11 a.m. 2 a.m. EST month’s second Full Moon, it 76 minutes of totality, the Moon PST. Observers in Alaska and is in conjunc- also will be touted as a “Blue should take on an orange glow, Hawaii can watch the final tion with the , 5 a.m. EST Moon.” But to observers, the looking a bit like a Chinese lan- penumbral phases play out as January 31 Full Moon places tern dangling among the back- the Moon departs Earth’s 11 The Moon passes 4° north of Jupiter, first because it dives deeply ground of Cancer, with lighter outer shadow. 1 a.m. EST into Earth’s shadow, bringing Leo standing above. If the Moon’s position dur- The Moon passes the first total lunar eclipse Observers in the western ing totality seems familiar to 5° north of Mars, since September 2015. third of the U.S. get to see all you, it should. When the New 5 a.m. EST People across North of totality, and progressively Moon passed between the Sun 13 Mercury passes 0.6° America, the Pacific Ocean, more of the concluding partial and Earth last August 21, it south of Saturn, Australia, and Asia can see at phases the farther west they created a total solar eclipse in 2 a.m. EST least part of this eclipse. For live. People with clear skies in Leo. In the nearly half-year 14 The Moon passes those in the United States, bet- northern California, Oregon, since, the Sun has moved 3° north of Saturn, 9 p.m. EST ter views come the farther west and Washington can witness almost halfway around the sky, you live. Those in the eastern the entire umbral eclipse, so the Full Moon (which lies 15 The Moon passes 3° north of opposite the Sun) appears in Mercury, 2 a.m. EST N the same general area as last August’s New Moon. 20 The Moon passes Penumbra 1.6° south of The January 31 eclipse is Neptune, 3 p.m. EST the first of five during 2018, Partial 23 The Moon passes Umbra eclipse begins though it is by far the best for 5° south of , A.M. PST Partial Greatest eclipse 3:48 North Americans. A second 8 p.m. EST 5:30 A.M. PST E eclipse ends total lunar eclipse occurs 27 The Moon passes 7:11 A.M. PST July 27, but it completely 0.7° north of Aldebaran, misses the continent. The year 6 a.m. EST Penumbral also features three solar eclipse begins eclipses — on February 15, 31 2:51 A.M. PST is at , Totality ends Totality begins July 13, and August 11 — but 8 a.m. EST Penumbral 6:08 A.M. PST 4:52 A.M. PST all are partials. The first two eclipse ends Total lunar eclipse, favor observers deep in the 8:08 A.M. PST 8 a.m. EST Southern Hemisphere, while The first total lunar eclipse since September 2015 graces the predawn skies the last occurs in northern above North America onASY-PB-618364_20 January 31. ALL ILLUSTRATIONS: ASTRONOMY: ROEN KELLY Europe and northern Asia.

2 Sky Guide 2018 2018 Feb. Target galaxies these S M T W T F S 1 2 3 4 5 6 8 9 10 cool winter nights 11 12 13 14 16 17 18 19 20 21 22 24 25 26 27 28 ate winter and early spring are superb times for hunters. By late eve- ning, Earth’s night- 1 The Moon passes 1.0° north of side has turned away from the L Regulus, 2 p.m. EST myriad stars and obscuring 7 The Moon passes clouds of gas and dust in the 4° north of Jupiter, Milky Way’s plane. In its place, 3 p.m. EST countless galaxies from the 8 The Moon passes depths of intergalactic space 4° north of Mars, swing into view. midnight EST To spot these “faint fuzzies,” 10 Mars passes 5° you’ll need a dark sky and a north of Antares, telescope. Choose a clear night 10 a.m. EST within a week of the New 11 The Moon passes 2° north of Saturn, Moon and plan an escape 10 a.m. EST from light-polluted skies to The beautiful spiral galaxies M81 (right) and M82 in Ursa Major make a fine Juno is in starting point for an evening of galaxy hunting. JASE JENNINGS 14 the darkness of the country. conjunction with Your reward will be a treasure the Sun, 6 a.m. EST trove of spirals, ellipticals, and wonders lurking in Canes southwest lies a 9th-magnitude 15 Partial solar eclipse, clusters of galaxies. Venatici and Coma Berenices, elliptical, M85, which marks 4 p.m. EST The first good opportunity followed soon after by the the northern edge of the giant 17 Mercury is in supe- this year comes around the mother lode in Virgo. Let’s Virgo Cluster. rior conjunction, New Moon on February 15. start with the four 8th- and From M85 south into 7 a.m. EST The Last Quarter Moon exits 9th-magnitude galaxies in Virgo lie some two dozen gal- 20 The Moon passes Virgo and enters Libra on Canes Venatici. The standout axies that glow at 11th magni- 5° south of Uranus, 3 a.m. EST February 7, marking the start here is the Whirlpool Galaxy tude or brighter. All told, the of the galaxy-viewing season. (M51), a dazzling spiral that is cluster contains more than 23 The Moon passes 0.7° north Dark skies stretch through the a favorite of astroimagers. Aim 1,500 galaxies. The largest is of Aldebaran, 21st, when the waxing cres- your telescope 12° due west M87, a giant elliptical with a 1 p.m. EST cent Moon sets shortly before and you’ll land on another nice central black hole weighing midnight local time. spiral, M106. The Hunting several billion . Several The tip of the galactic ice- Dogs boast two more gems other cluster members dwarf berg comes into view as Ursa — M63 and M94 — farther the Milky Way. Moon phases Major climbs in the northeast. south. M63 has broad spiral The Virgo Cluster spans First Quarter A great pair of galaxies, M81 arms in contrast to M94’s tight 15°. Ponder that as you gaze Full Moon and M82, reaches the same spiral. Small telescopes show toward Virgo and Coma altitude as Polaris around the core of each galaxy as a Berenices — a cluster of galax- Last Quarter 7 p.m. local time, just as twi- faint smudge similar to a com- ies some 55 million light-years New Moon light ends. About three hours et’s head, while larger scopes distant so big that it spans later, Leo achieves the same reveal the fainter extremities. nearly 5 percent of the sky! Events that can be viewed height in the east. The Lion Head 17° due south of The gravity from all the stars, with the holds two tight groups of fine Cor Caroli, Canes Venatici’s dust, and gas here noticeably Events that can be viewed galaxies: M95, M96, and M105 brightest , to find the Black pulls on our own Local Group. with in its midsection and M65 and Eye Galaxy (M64) in Coma If you miss a February date Events that can be viewed M66 in its hindquarters. Berenices. This galaxy gets its with these galaxies, you can try with a telescope Around that same time, you name from a distinctive band again around the New Moons can get your first views of the of obscuring dust. To its on March 17 and April 15.

www.Astronomy.com 3 2018 March S M T W T F S Catch Mercury 2 3 4 5 6 7 8 10 11 12 13 14 15 16 at dusk 18 19 20 21 22 23 25 26 27 28 29 30 he innermost stands 18° east of the planet continu- Sun. You can try to ously plays a game spot the planet as of hide-and-seek early as March 5. On 1 The Moon passes with the Sun. Its that evening, magni- 0.9° north of tight around our star tude –3.9 Venus is Regulus, 1 a.m. EST T means Mercury follows a easy to locate some 4 Neptune is in con- junction with the never-ending pattern: It pops 6° above the western Sun, 9 a.m. EST briefly into view at dusk, gets horizon a half-hour NASA’s MESSENGER spacecraft revealed Mercury as a heavily cratered world that nevertheless 5 Mercury passes 1.4° swallowed by the Sun’s glare, after sunset. Mercury shows signs of recent geological activity. north of Venus, reappears for a few weeks lies 1.5° north (upper Through amateur telescopes, however, the inner 1 p.m. EST before dawn, disappears in right) of its neighbor. planet appears as a bland disk. NASA/JHUAPL/CIW 7 The Moon passes the solar glow once more, and Glowing at magni- 4° north of Jupiter, finally re-emerges after sunset. tude –1.1, the innermost days. At greatest elongation 2 a.m. EST The best times to view the planet should show up to the on the 15th, Mercury stands 9 The Moon passes inner planet from the Northern naked eye, though binoculars 12° high and due west a half- 4° north of Mars, Hemisphere come when three make it easier to spot initially. hour after sunset with Venus 8 p.m. EST conditions coincide: It lies near As both pull away 4° to its lower left. Mercury 10 The Moon passes 2° north of Saturn, its greatest elongation from the from the Sun, they linger lon- then shines at magnitude –0.3 9 p.m. EST Sun, it stands north of the ger in twilight. On March 10, and appears 7.5" across and 15 Mercury is at (the Sun’s apparent path Venus stands 7° high 30 min- 43 percent lit, while Venus greatest eastern across our sky), and the ecliptic utes after sundown with remains essentially unchanged elongation (18°), inclines steeply to the horizon. Mercury 3.5° above it. Target from earlier. 11 a.m. EDT Mercury checks all three boxes each planet through a tele- Be sure to keep an eye on 17 Mercury passes 4° on March evenings. The elusive scope and you’ll see Mercury’s the western sky March 18, north of Venus, planet proves even easier to 6.5"-diameter disk, which when a slender crescent Moon 9 p.m. EDT find this month because bril- appears nearly two-thirds lit; appears 4° to Venus’ left and 18 The Moon passes 8° south of liant Venus follows a similar Venus spans 10" and is 97 per- Mercury hangs 4° to Venus’ Mercury, 2 p.m. EDT track and serves as a guide. cent illuminated. upper right. The trio makes a The Moon passes Mercury reaches greatest The two planets climb in dramatic scene in evening twi- 4° south of Venus, elongation March 15, when it unison for the next several light. The two planets separate 3 p.m. EDT after this, with Venus climbing 19 The Moon passes higher and Mercury dipping 5° south of Uranus, PISCES lower. The innermost planet noon EDT disappears in the Sun’s glare 20 Equinox (northern within a week. spring/southern Mercury reaches greatest autumn begins), PEGASUS noon EDT eastern elongation again Mercury July 11/12 and November 6, 22 The Moon passes 0.9° north Venus though it doesn’t climb as high of Aldebaran, CETUS as it does in March. The planet 7 p.m. EDT puts on three almost equally 28 The Moon passes nice morning apparitions in 5° 1.0° north of 2018. You can find it about 10° Regulus, 10 a.m. EDT above the eastern horizon March 15, 30 minutes after sunset Looking west 30 minutes before sunrise around its greatest western Mercury stands above theASY-PB-618364_21 western horizon during evening twilight at its elongations January 1, March 15 peak. Use brilliant Venus as a guide to find the innermost planet. August 26, and December 15.

4 Sky Guide 2018 2018 April The Lyre plays a S M T W T F S 1 2 3 4 5 6 7 9 10 11 12 13 14 sweet meteor song 16 17 18 19 20 21 23 24 25 26 27 28 30 f meteor observers were granted one wish, it would be for all major meteor showers to occur with the Moon out of the 1 Mercury is in infe- rior conjunction, sky. Earth’s atmosphere scat- I 2 p.m. EDT ters bright moonlight, wash- 2 Mars passes 1.3° ing out fainter meteors and south of Saturn, rendering the brighter ones 8 a.m. EDT less impressive. Alas, nature 3 The Moon passes can’t grant this wish — the 4° north of Jupiter, seven major meteor showers 10 a.m. EDT fall at different times of the A bright Lyrid meteor streaks between the Big Dipper and Boötes 7 The Moon passes lunar month, ensuring that at at the peak of the 2013 shower. JOHN CHUMACK 1.9° north of least some coincide with a Saturn, 9 a.m. EDT blazing lunar presence. atmosphere incinerates the takes center stage. But the The Moon passes 3° north of Mars, Fortunately, April’s Lyrid dust and produces the streaks cycle of lunar phases lasts 2 p.m. EDT shower peaks on the 22nd of light we see. Perspective 29.5 days, so good circum- 12 The Moon passes under a First Quarter Moon. makes the meteors appear to stances for the Lyrids guaran- 1.9° south of Although fairly bright, the come from one direction, tee poor conditions for the Neptune, 7 p.m. EDT half-lit Moon sets by 2 a.m. called the radiant, and the Eta Aquariids. A waning gib- 14 The Moon passes local daylight time, which pro- that contains it bous Moon shares the sky at 4° south of vides nearly three hours for gives the shower its name. The the latter shower’s May 6 peak. Mercury, 5 a.m. EDT meteor viewing before twilight Lyrids radiate from Lyra the Everyone looks forward to 17 The Moon passes begins. Because artificial lights Lyre, which climbs highest the Perseid meteor shower in 5° south of Venus, can brighten the sky as effec- before dawn. August because it coincides 3 p.m. EDT tively as the Moon, your best The meteor year doesn’t with warm nights and vaca- 18 Uranus is in con- junction with the views will come from a dark start out as well. Although the tion season. And this year, the Sun, 10 a.m. EDT site. Under optimal conditions, Quadrantids in early January shower peaks on the 12th near 19 The Moon passes observers can see an average of can deliver up to 120 meteors New Moon, providing optimal 1.1° north up to 18 meteors per hour. per hour under a Moon-free conditions. See p. 9 for further of Aldebaran, The Lyrids result when sky, the Full Moon on the details about 2018’s premier 1 a.m. EDT Earth runs into dust particles night of January 1/2 likely meteor show. 22 Lyrid meteor ejected by Comet Thatcher will reduce that number by You’ll also want to carve shower peaks (C/1861 G1). As Earth plows 80 percent or more. out some observing time for 24 The Moon passes through this debris trail, fric- Two weeks after the Lyrids the year’s final three major 1.2° north of tion with molecules in our peak, the Eta Aquariid shower meteor showers. Although the Regulus, 4 p.m. EDT Orionids (at maximum 29 Mercury is at great- est western elonga- October 21) and Leonids Meteor showers in 2018 tion (27°), 2 p.m. EDT (November 17) both peak Name Peak date Moon’s phase Prospects 30 The Moon passes under a waxing gibbous 4° north of Jupiter, Quadrantids Jan. 3 Full Moon Poor Moon, it sets before twilight 1 p.m. EDT Lyrids April 22 First Quarter Good begins and thus offers at least a Eta Aquariids May 6 Waning gibbous Poor couple of hours of Moon-free Perseids Aug. 12 New Moon Excellent viewing. The Geminids fare Orionids Oct. 21 Waxing gibbous Fair even better. At their peak the Leonids Nov. 17 Waxing gibbous Fair night of December 13/14, the Geminids Dec. 14 Waxing crescent Good Moon is a waxing crescent that sets before 11 p.m. local time.

www.Astronomy.com 5 2018 May Jupiter rules spring S M T W T F S 1 2 3 4 5 N 6 8 9 10 11 12 nights β 13 14 16 17 18 19 ε 20 22 23 24 25 26 LIBRA 27 28 30 31 hen Jupiter reaches E opposition μ and peak Jupiter reaches 3 Venus passes 7° visibility opposition May 8 July 10 north of Aldebaran, May 8, it launches a three- ο June 10 1 p.m. EDT W month planetary spectacular. ν May 10 α 4 The Moon passes 1.7° north of Three major planets appear April 10 March 10 Saturn, 4 p.m. EDT their best in consecutive 1° 6 The Moon passes months, with Saturn peaking 3° north of Mars, in late June and Mars a month The solar system’s biggest planet shines some 100 times brighter than any 3 a.m. EDT after. Of course, all three will of the background starsASY-PB-618364_22 in this year’s host constellation, Libra the Scales. Eta Aquariid remain worthy subjects for meteor shower several months around their until January 7, when only 0.2° to observe it when it’s highest peaks oppositions. separates them. in the sky between roughly 8 Jupiter is at oppo­ Jupiter spends most of Jupiter rises about two 11 p.m. and 3 a.m. The added sition, 9 p.m. EDT 2018 among the background hours earlier each month. It altitude lets you avoid the haze 10 The Moon passes stars of Libra the Scales. The drifts slowly eastward relative and turbulence that mar views 2° south of Neptune, 5 a.m. EDT giant planet is already a fine to the starry backdrop, reach- closer to the horizon. predawn object in January. On ing a point 8° east of Alpha Lib The most prominent fea- 12 Mercury passes 2° south of Uranus, New Year’s morning, it rises in early March, when it begins tures on the gas giant’s disk are 5 p.m. EDT around 3 a.m. local time and a westward sojourn that takes two dark belts, one on either 13 The Moon passes climbs some 25° high by the it back toward the star. side of a brighter zone that 5° south of Uranus, time twilight begins. It shines By the time the planet coincides with the planet’s 11 a.m. EDT brilliantly at magnitude –1.8 reaches opposition in early equator. Although you can see The Moon passes and stands 2° east of 3rd- May, it has pulled within 3° of these bands as soon as you 2° south of magnitude Zubenelgenubi Zubenelgenubi. Jupiter then focus your telescope, linger a Mercury, 1 p.m. EDT (Alpha [α] Librae). rises around sunset, climbs bit longer. Finer details pop 16 The Moon passes But even more impressively, nearly halfway to the zenith into view during moments of 1.2° north of Aldebaran, magnitude 1.5 Mars lies just 1° around 1 a.m. local daylight good seeing. 9 a.m. EDT northwest of the same star. time, and sets at dawn. It Any telescope also reveals 17 The Moon passes The two planets approach each shines at magnitude –2.5, far up to four bright moons. 5° south of Venus, other (leaving the star behind) brighter than any other point These satellites circle Jupiter in 2 p.m. EDT of light in the sky once Venus periods ranging from 1.8 to 27 The Moon passes sets around 10 p.m. 16.7 days. If you don’t see all 4° north of Jupiter, Jupiter should look stun- four, it means one or more of 2 p.m. EDT ning through any telescope. them lies in front of or behind 31 The Moon passes Its apparent diameter the giant world. 1.6° north of swells to 45" at opposi- After opposition, Jupiter’s Saturn, 9 p.m. EDT tion, some 12" bigger trek carries it 0.9° north of than it was in early Zubenelgenubi on June 6. Its 2018. Even though it is westward motion continues up all night, you’ll want into July’s second week, when Jupiter’s banded atmosphere it reverses course and starts to and the Great Red Spot show head eastward. Jupiter then lies up nicely through amateur due south in evening twilight, instruments, though not in the detail seen in this image shining at magnitude –2.2 from the Cassini spacecraft. and spanning 40" through a NASA/JPL/UNIVERSITY OF ARIZONA telescope.

6 Sky Guide 2018 2018 Saturn’s rings on June S M T W T F S 1 2 gorgeous display 3 4 5 7 8 9 10 11 12 14 15 16 17 18 19 21 22 23 What can you see on 24 25 26 27 29 30 Saturn? Around opposition, the planet’s globe measures 18" across the equator and the ring system spans 42" and tips 3 The Moon passes 3° north of Mars, 26° to our line of sight. The 8 a.m. EDT wide tilt, just 1° less than the 5 Mercury is in supe­ maximum last year, affords rior conjunction, Saturn’s rings tilt 26° to our line of sight this summer, wide enough to show observers great views of ring 10 p.m. EDT exquisite detail through small telescopes. NASA/ESA/THE HUBBLE HERITAGE TEAM (STScI/AURA) structure. The Cassini Division 6 The Moon passes — the dark gap between the 2° south of he second planet to clusters more exciting. The outer A ring and brighter B Neptune, 2 p.m. EDT come to opposition ringed world slides 1.6° north ring — should stand out 8 Venus passes 5° in 2018’s spring- of 5th-magnitude M22 during clearly through any telescope. south of Pollux, summer extrava- May’s second week and 2.4° The planet’s cloud features are 9 p.m. EDT ganza is Saturn. north of 7th-magnitude M28 subtle thanks to high altitude 9 The Moon passes 5° south of Uranus, The ringed world reaches this in late June. Use binoculars for haze. Nevertheless, keep a T 11 p.m. EDT milestone June 27, when it the best looks. watch for bright white clouds, 16 The Moon passes shines brightest, appears larg- Of course, Saturn is visually which may indicate a major 2° south of Venus, est through a telescope, and unremarkable until you turn a storm breaking through. 9 a.m. EDT remains visible all night. telescope on it. As with Jupiter, Let Saturn’s moons be your 19 Asteroid Vesta is Saturn rises some four hours wait for the ringed planet to final targets. Any telescope at opposition, after Jupiter, so it lies low in climb high in the south to shows 8th-magnitude Titan, 4 p.m. EDT the southeast just as Jupiter avoid the worst of Earth’s tur- while you’ll need a 4-inch 21 Solstice (northern climbs highest in the south. bulent atmosphere. The best scope to see 10th-magnitude summer/southern Saturn resides in Sagittarius times in late June are between Tethys, Dione, and Rhea. The winter begins), 6 a.m. EDT throughout 2018. It spends the 11 p.m. and 3 a.m. local day- same instrument reveals two- 23 The Moon passes peak late spring and summer light time. Add two hours to faced Iapetus when it glows 4° north of Jupiter, months a few degrees north of these times for each month brightest within a week of 3 p.m. EDT 3rd-magnitude Lambda (λ) earlier and subtract two hours greatest western elongation 25 Mercury passes 5° Sagittarii, the star at the tip of for each month later. (the night of June 11/12). south of Pollux, the constellation’s conspicuous noon EDT Teapot asterism. The planet N 27 Saturn is at oppo­ passes 3° due north of Lambda 21 sition, 9 a.m. EDT in mid-June and 1.6° due The Moon passes south of 4th-magnitude μ 1.8° north Saturn reaches Mu (μ) Sgr in early August. of Saturn, opposition June 27 14 midnight EDT Both stars pale in comparison May 1 30 The Moon passes to Saturn, however, which E June 1 July 1 Aug 1 5° north of Mars, shines at magnitude 0.0 at Sept 1 10 p.m. EDT opposition and only a few tenths of a magnitude fainter 11 M22 SAGITTARIUS in the surrounding months. Although the planet’s con- junctions with these stars are M28 worth viewing with naked eyes λ 1° and binoculars, most observ- ers will find Saturn’s passage The ringed world spends 2018 in Sagittarius. Shining at magnitude 0, by a pair of bright globular the planet appears far brighterASY-PB-618364_23 than any of the Archer’s stars.

www.Astronomy.com 7 2018 July Red Planet S M T W T F S 1 2 3 4 5 7 8 9 10 11 13 14 renaissance 15 16 17 18 20 21 22 23 24 25 26 28 29 30 31 he dramatic plan- magnitude 1.4 etary threesome while Jupiter culminates in July gleams at magni- with Mars’ closest tude –1.8, some 20 3 The Moon passes approach to Earth times brighter. By late 3° south of in 15 years. On the 31st, the July, the Red Planet Neptune, 8 p.m. EDT T Red Planet edges within reaches magnitude –2.8 and 7 The Moon passes Mars puts on its best show in 5° south of Uranus, 35.8 million miles of Earth, just makes Jupiter look faint in 15 years this summer, delivering 10 a.m. EDT 1.2 million miles farther away comparison. spectacular views through a telescope. ESA/MPS/OSIRIS TEAM 9 Venus passes 1.1° than in August 2003. This During the first half of 2018, north of Regulus, 3 percent difference means Mars races from Libra across 4 p.m. EDT Mars’ apparent diameter is just Scorpius, Ophiuchus, and and magnitude –2.0 on June 10 The Moon passes 0.8" smaller than it was during Sagittarius before entering 25. This rapid brightening 1.1° north that historic apparition. Capricornus. It passes 5° north coincides with a surge of Aldebaran, Not all of the news is great, of the 1st-magnitude star in apparent size when viewed 6 a.m. EDT however, at least for Northern Antares on February 10 and 1.3° through a telescope. Its diam- 12 Mercury is at great- est eastern elonga- Hemisphere observers. At its south of Saturn on April 2. The eter swells from 5" on January tion (26°), 1 a.m. EDT peak in late July, Mars lies in ruddy world also passes some 1 to 10" on April 21, 15" on Pluto is at opposi- southern Capricornus at a notable deep-sky objects during May 31, and 20" on June 27. tion, 6 a.m. EDT of –26°. For view- its trek across Sagittarius. Look These changes start to become Partial solar eclipse, ers at 40° north latitude, this for Mars between the Lagoon visible to evening observers 11 p.m. EDT means the planet climbs only (M8) and Trifid (M20) nebulae once the planet rises before 14 The Moon passes 24° above the southern horizon March 19. The planet then slides midnight local daylight time 2° north of at its best. 0.4° north of globular cluster beginning in early June. Mercury, 6 p.m. EDT Mars remains visible M22 on April 1 and 2, and 0.3° These advances build to a 15 The Moon passes throughout 2018. In early south of globular cluster M75 on dazzling peak during July’s 1.6° north of Venus, January, you can find it in the May 14. final week. Mars reaches oppo- midnight EDT morning sky near Jupiter. The Throughout this period, sition the night of July 26/27 20 The Moon passes planets pass within 0.2° of each Mars brightens steadily. It and comes closest to Earth on 4° north of Jupiter, 8 p.m. EDT other at the end of the year’s reaches magnitude 0.0 on April the 31st. The planet shines bril- first week. Mars shines at 13, magnitude –1.0 on May 23, liantly at magnitude –2.8, spans 25 The Moon passes 2° north of Saturn, 24.3", and remains visible from 2 a.m. EDT N dusk to dawn. The Full Moon 27 Mars is at opposi- passes 7° north of the planet tion, 1 a.m. EDT and deep into Earth’s umbral Total lunar eclipse, shadow on the 27th. Viewers in 4 p.m. EDT July 1 Mars reaches Europe, Africa, Asia, and The Moon passes opposition Australia will see a total lunar July 26/27 7° north of Mars, eclipse — and a stunning juxta- 6 p.m. EDT E 15 position of two orange-red The Moon passes 31 ψ celestial orbs. 3° south of 31 Mars remains a fixture in Neptune, 2 a.m. EDT ω Aug 1 15 the evening sky until the end 62 CAPRICORNUS of the year. And it shouldn’t be an afterthought: Its diameter exceeds 10" until 1° SAGITTARIUS November 21, and it remains The Red Planet resides in Capricornus around its late July peak, when it brighter than magnitude 0.0 shines at magnitude –2.8ASY-PB-618364_24 and swells to 24" in apparent diameter. until December 6.

8 Sky Guide 2018 2018 Prime time for Aug. S M T W T F S 1 2 3 the Perseids 5 6 7 8 9 10 12 13 14 15 16 17 19 20 21 22 23 24 25 f three months of bright 27 28 29 30 31 planets reaching memo- rable oppositions don’t satisfy your observing appetite, let August pro- 3 The Moon passes 5° south of Uranus, vide a feast of a different kind I 5 p.m. EDT — the best meteor show of 6 The Moon passes 2018. The peak of the Perseid 1.1° north shower coincides with New of Aldebaran, Moon this year, providing 3 p.m. EDT optimal viewing conditions. 7 Asteroid Pallas is in The shower begins July 17 conjunction with the Sun, 9 a.m. EDT and remains active until A Perseid meteor streaks toward the horizon August 13, 2017. Viewing August 24, though most mete- conditions for this year’s shower promise to be even better. TONY ROWELL 8 Mercury is in infe- ors rain down around the rior conjunction, 10 p.m. EDT peak on the night of August Partial solar eclipse, 12/13. With this month’s New 11 6 a.m. EDT Moon arriving on the 11th, CASSIOPEIA 12 Perseid meteor there won’t be any natural Polaris ANDROMEDA shower peaks light interfering. Meteor Radiant 14 The Moon passes watchers also should avoid 6° north of Venus, artificial light pollution by ARIES 10 a.m. EDT seeking viewing sites well 17 The Moon passes away from cities and towns. PERSEUS 5° north of Jupiter, 7 a.m. EDT Perseid meteors derive Capella Pleiades from Comet 109P/Swift-Tuttle. AURIGA Venus is at greatest Each time this comet enters eastern elongation (46°), 1 p.m. EDT the inner solar system — its 10° 133-year orbit last brought it 21 The Moon passes 2° north of Saturn, through in 1992 — it lays August 13, 1 A.M. Looking northeast 6 a.m. EDT down a trail of dusty debris. 23 The Moon passes And each August, Earth Perseid meteors appearASY-PB-618364_25 to radiate from a point in the constellation 7° north of Mars, crosses this debris stream. Perseus, which climbs high in the northeast in August’s predawn sky. 1 p.m. EDT Although the dust particles 26 Mercury is at great- travel through space on paral- planet plows head-on through climbs 60° high before dawn, est western elonga- lel paths, our perspective the cometary debris. Imagine which reduces the peak rate to tion (18°), 5 p.m. EDT makes the meteors appear to Earth as a car and the meteors around 95 per hour. 27 The Moon passes radiate from a single point. as snowflakes — our “front Remember not to look 2° south of Neptune, 6 a.m. EDT This so-called radiant lies in windshield” sweeps up the vast directly toward the radiant. the constellation Perseus, majority of dust particles. You’ll see longer and more 30 The Moon passes 5° south of Uranus, which gives the shower its At its best, the Perseid impressive streaks of light 11 p.m. EDT name. Perseus appears low in shower delivers an average of some distance away. A good the northeast in late evening 110 meteors per hour. But to rule of thumb is to watch a and climbs higher as the night see this many, you need to patch of sky roughly 45° from progresses. It reaches an alti- observe from a site that lets Perseus and a similar distance tude of 60° an hour before twi- you see stars down to magni- above the horizon. Bring a light starts to paint the sky. tude 6.5 and have the radiant reclining lawn chair to your The best views come during directly overhead. From mid- dark site, sit back, relax, and the early morning hours as our northern latitudes, the radiant enjoy the show.

www.Astronomy.com 9 2018 Sept. Venus blazes in the S M T W T F S 1 3 4 5 6 7 8 evening twilight 10 11 12 13 14 15 17 18 19 20 21 22 23 25 26 27 28 29 diameter swells. On September 30 1, Venus dazzles at magnitude –4.6. Look through binoculars and you’ll find Virgo’s bright- 2 Venus passes 1.4° est star, 1st-magnitude Spica, south of Spica, just 1.4° to its north (upper 5 a.m. EDT right). The planet appears The Moon passes 1.2° north 180 times brighter. A telescope of Aldebaran, reveals Venus’ 30"-diameter 10 p.m. EDT disk and 40-percent-lit phase. 5 Mercury passes 1.0° At its brightest on the 21st, north of Regulus, Venus spans 40" and appears 7 p.m. EDT one-quarter lit. Although it 7 Neptune is at stands barely 5° high a half- opposition, hour after sunset, its glow eas- 2 p.m. EDT No celestial object besides the Sun and Moon shines brighter than Venus. ily pierces the twilight. The Moon passes 12 The inner planet peaks at magnitude –4.8 September 21. JOHN CHUMACK 10° north of Venus, The inner planet disappears noon EDT in twilight in early October he sky’s brightest naked eye or binoculars. But and passes between the Sun 13 The Moon passes 4° north of Jupiter, planet rules it’s also worth observing Venus and Earth on October 26. But 10 p.m. EDT evenings from through a telescope. On the it quickly emerges before dawn 17 The Moon passes early March into 17th, it displays a disk 24" in November. It reaches great- 2° north of Saturn, October, reaching across and nearly half-lit. est brilliancy once again noon EDT Tpeak brightness September 21. Although Venus’ phase December 1, when it shines at 20 The Moon passes At greatest brilliancy, Venus diminishes during the next magnitude –4.9. It then rises 5° north of Mars, shines at magnitude –4.8 and month, the planet continues to more than three hours before 3 a.m. EDT hangs low in the west-south- brighten as it comes closer to the Sun and stands 20° high at Mercury is in supe- rior conjunction, west a half-hour after sunset. Earth and its apparent the start of twilight. 10 p.m. EDT Despite this September pin- nacle, Earth’s closest neighbor 21 Venus is at greatest OPHIUCHUS brilliancy, 9 a.m. EDT appears spectacular in the 22 Equinox (northern western sky on spring and Arcturus autumn/southern summer evenings. During most spring begins), of this period, Venus sets about Antares BOÖTES 10 p.m. EDT two hours after the Sun. But the SCORPIUS 23 The Moon passes summer scenes provide more Jupiter 2° south of interest because the planet Neptune, noon EDT LIBRA shares the late-evening stage 27 The Moon passes 5° south of Uranus, with Mars, Jupiter, and Saturn. 3 a.m. EDT Venus crosses Leo in July, VIRGO passing 1.1° north of Regulus Venus Spica on the 9th, before entering Virgo on August 1. The planet 10° reaches greatest elongation August 17, when it lies 46° east September 21, 30 minutes after sunset of the Sun and stands 15° high Looking west-southwest a half-hour after sundown. Gleaming at magnitude –4.5, The night sky’s two brightestASY-PB-618364_26 points of light — Venus and Jupiter — lie near it’s a stunning sight with the each other in late September’s evening sky.

10 Sky Guide 2018 2018 An ice giant butts Oct. S M T W T F S 1 3 4 5 6 into the Ram 7 9 10 11 12 13 14 15 17 18 19 20 21 22 23 25 26 27 urking at the edge of 28 29 30 the Sun’s planetary system, far from our star’s intense light, two major planets 5 Mercury passes 2° north of Spica, rule the darkness. Uranus and L 2 p.m. EDT Neptune both make tempting 7 Dwarf planet Ceres targets this autumn. Uranus is in conjunction reaches opposition and peak with the Sun, visibility October 23, when it 6 a.m. EDT lies in the southwestern corner 10 The Moon passes of Aries the Ram. Neptune 13° north of Venus, comes to opposition about Amateur telescopes show Uranus as a small disk with a distinct blue-green 11 a.m. EDT seven weeks earlier, on color. This image through the 10-meter Keck II Telescope reveals cloud 11 The Moon passes structures and the planet’s dark rings. LAWRENCE SROMOVSKY (UW-MADISON)/ 4° north of Jupiter, September 7, against the back- KECK OBSERVATORY 5 p.m. EDT drop of the Water- 14 Mercury passes 7° bearer. Their slow treks through Point your telescope at the pair Neptune holds steady at north of Venus, the solar system’s distant and Uranus reveals itself magnitude 7.8 from 11 a.m. EDT recesses mean they remain near thanks to its 3.7"-diameter disk mid-July to early November. The Moon passes the same locations for months. and distinctive blue-green hue. To track this planet down, 1.8° north of Both ice giant worlds are Uranus pulls closer to this locate the 4th-magnitude stars Saturn, 11 p.m. EDT within reach of binoculars. star over the next few weeks, Lambda (λ) and Phi (ϕ) 18 The Moon passes Uranus is the easier target, passing 15' due south of it Aquarii. At opposition 1.9° north of Mars, peaking at magnitude 5.7 at November 10. For several days September 7, the planet lies 9 a.m. EDT opposition but staying above around then, the pair resem- nearly midway between these 20 The Moon passes magnitude 5.8 from July bles a rapidly changing binary two — 3.3° east of Lambda 3° south of Neptune, 6 p.m. EDT through December. It’s even system. The planet continues and 2.3° west of Phi — and just 21 Orionid meteor bright enough to spot with the to move westward and crosses 0.8° north of 5th-magnitude shower peaks naked eye under a dark sky. into Pisces in early December. 83 Aqr. A telescope reveals 23 Uranus is at oppo­ Uranus has been swimming By New Year’s Eve, Uranus Neptune’s 2.4"-diameter disk sition, 9 p.m. EDT in Pisces the Fish for the past appears 1.2° north of Omicron. and subtle blue-gray color. 24 The Moon passes several years, and the best 5° south of Uranus, guide star for finding the N 9 a.m. EDT η planet remains in this constel- 26 Venus is in inferior lation. Fourth-magnitude conjunction, ARIES Omicron (ο) Piscium lies near 10 a.m. EDT Pisces’ eastern border. In early 29 Mercury passes 3° September, this region climbs south of Jupiter, π midnight EDT 30° high in the east by mid- night local daylight time. E Uranus Once you locate Omicron, scan 4° northeast to pick up ξ Uranus. The planet’s westward ο PISCES motion carries it within 3° of CETUS Omicron by its October 23 opposition. Don’t confuse 1° Uranus with a similarly bright field star, which stands 0.7° Uranus shines at magnitude 5.7 against the background stars of Aries at west of the planet on the 23rd. opposition October 23, ASY-PB-618364_27not far from 4th-magnitude Omicron (ο) Piscium.

www.Astronomy.com 11 2018 Nov. Juno at its best S M T W T F S 1 2 3 4 5 6 8 9 10 in 35 years 11 12 13 14 16 17 18 19 20 21 22 24 25 26 27 28 30 steroid N reaches opposi- tion November 25 17, when it Nov 1 5 The Moon passes shines brighter 24 10° north of Venus, 35 than it has in a third of a cen- 9 p.m. EST A 6 tury. The minor planet peaks Mercury is at 6 at magnitude 7.4 and will be 11 greatest eastern E 32 elongation (23°), easy to spot through binocu- 16 10 a.m. EST lars. Even better, it remains ERIDANUS 21 Path of Juno 9 Mercury passes 1.8° above magnitude 8.0 from north of Antares, 26 mid-October to late December. Dec 1 1 a.m. EST German astronomer Karl The Moon passes Harding discovered Juno on 7° north of September 1, 1804. It was the Mercury, 7 a.m. EST 1° 30 22 third object found in the gap 11 The Moon passes 1.5° north of between the of Mars and Asteroid Juno reaches 7th magnitude at its November peak, the brightest it has been since 1983. It ASY-PB-618364_28then lies against the backdrop of northern Eridanus. Saturn, 11 a.m. EST Jupiter, following the sightings of Ceres and Pallas in the pre- 15 The Moon passes 1.0° south of Mars, vious three years. Juno’s egg- Nu (ν) Tauri. With binoculars magnitude 7.6 and is an easy 11 p.m. EST shaped orbit occasionally in hand, identify the 5th- binocular object. Juno appears 17 The Moon passes brings it closer to the Sun than magnitude star 40 Tau 0.6° to 0.1° southeast of 35 Eri on the 3° south of most major . If it hap- the south. Juno lies the same 4th and 0.3° south of the same Neptune, 1 a.m. EST pens to reach opposition near distance south of 40 Tau. No star the next night. This region Asteroid Juno is this time, as it does in 2018, it other star of similar brightness rises by 7 p.m. local time and at opposition, brightens considerably. lies in this area. To confirm a peaks due south around 1 a.m. 5 p.m. EST You can start hunting sighting, come back the follow- Over the next week, Juno Leonid meteor shower peaks for Juno on October 1. The ing night and notice the object moves about 2° southwest and asteroid then glows at mag­ has moved noticeably farther reaches the vicinity of 32 Eri. 20 The Moon passes 5° south of Uranus, nitude 8.2 among the back- south of these guide stars. Shining at magnitude 4.7, this 3 p.m. EST ground stars of southern Juno heads south during star is 13 times brighter than 26 Jupiter is in con- Taurus. This area rises around October, crossing into the magnitude 7.5 asteroid. junction with the 10 p.m. local daylight time and Eridanus late in the month. At Juno remains within 0.5° of Sun, 2 a.m. EST climbs high in the south before the start of November, you this star from November 13–16. 27 Mercury is in infe- dawn. To find Juno, start at can find it 0.7° northeast of When it reaches opposition on rior conjunction, Aldebaran and scan 13° south- 5th-magnitude 35 Eridani. the 17th, the asteroid stands 4 a.m. EST west to pick up 4th-magnitude The asteroid has reached 0.6° southwest of 32 Eri. As Juno fades after opposi- Asteroids and dwarf planets tion, it continues its southwest- erly trek. On December 1, Name Opposition Constellation Magnitude the magnitude 7.6 object lies Ceres Jan. 31 Cancer 6.9 1.0° north-northeast of 6th- Flora Jan. 2 Gemini 8.2 magnitude 22 Eri. The asteroid Hebe Dec. 27 Monoceros 8.4 heads west and then north dur- Juno Nov. 17 Eridanus 7.4 ing December. On New Year’s Metis June 16 Ophiuchus 9.7 Eve, you can find it glowing Pluto July 12 Sagittarius 14.2 at magnitude 8.2 midway Vesta June 19 Sagittarius 5.3 between 4th-magnitude 10 Tau and 5th-magnitude 17 Eri.

12 Sky Guide 2018 2018 Making a swing past Dec. S M T W T F S 1 Earth 2 3 4 5 6 8 9 10 11 12 13 14 16 17 18 19 20 21 f Comet 46P/Wirtanen 23 24 25 26 27 28 plays nice, December will 30 31 feature a nice binocular comet riding high in the Northern Hemisphere 1 Venus is at greatest brilliancy, sky. Of course, comets have a I 11 p.m. EST notorious penchant to fizzle 3 The Moon passes before our eyes, and there are 4° north of Venus, no guarantees. 2 p.m. EST Here’s what’s working in 5 The Moon passes our favor this time: Comet Comet 46P/Wirtanen could reach 4th magnitude when it passes Earth this 1.9° north of Wirtanen skims within month. It appeared near the Flaming Star (IC 405) in 2008. JOHN CHUMACK Mercury, 4 p.m. EST 7.2 million miles of Earth on 7 Mars passes 0.04° north of Neptune, December 16, just four days N 21 10 a.m. EST after it makes its closest Algol approach to the Sun. The 8 The Moon passes 1.1° north of Saturn, PERSEUS coincidence between the two AURIGA midnight EST dates means Wirtanen could 19 14 Geminid meteor reach 4th magnitude in shower peaks mid-December. Keep in mind Path of Comet 46P/Wirtanen The Moon passes that its light will spread over a β 17 3° south of large area, so it won’t look as Neptune, 9 a.m. EST bright as a 4th-magnitude star. E TAURUS Pleiades The Moon passes Still, a comet this bright 4° south of Mars, should be easy to see through 15 6 p.m. EST ε binoculars and could reach 15 Mercury is at great- naked-eye visibility under a Aldebaran est western elonga- γ tion (21°), 7 a.m. EST dark sky. 13 You can start hunting for 17 The Moon passes 5° 5° south of Uranus, Wirtanen in early December, 11 p.m. EST when it lies in eastern Cetus. ORION Jupiter passes 5° Dec 11 19 On the 1st, it stands 3° west of north of Antares, 1 1 γ 4th-magnitude Tau (τ ) 9 p.m. EST Eridani. Its magnitude should The brightest periodic comet of 2018 journeys north through Taurus at its 21 Mercury passes 6° be a harbinger of what’s to December peak, passingASY-PB-618364_29 within 4° of the Pleiades (M45). north of Antares, come. Astronomers expect the 3 a.m. EST comet to glow around 5th mag- 2° east of Omicron. 16th, it has moved 4° east of the Mercury passes 0.9° nitude at this stage. If it does, we But the best is yet to come. cluster. Imagers should target north of Jupiter, 10 a.m. EST should be in for a good show. Wirtanen should peak when it these two nights for spectacular Wirtanen moves rapidly passes closest to Earth in mid- wide-field photos. Solstice (northern winter/southern north, crossing into Taurus December, and the comet then A waxing gibbous Moon summer begins), on December 11. The comet lies between the Pleiades star passes through Taurus from 5 p.m. EST appears 25° above the eastern cluster (M45) and the Hyades, December 19–21, and will con- horizon as darkness falls and the V-shaped cluster anchored tinue to hinder views through climbs highest in the south by 1st-magnitude Aldebaran. the 23rd, when the comet lies 1° around 10 p.m. local time. That On the 15th, the comet stands east of magnitude 0.1 Capella in evening, it lies 3° south of mag- 4° south of the Pleiades. Its Auriga. By the end of the year, nitude 3.6 Omicron (ο) Tauri. nearness to Earth causes it to Wirtanen passes into the north- The following night, it appears race across the sky, and by the eastern corner of Lynx.

www.Astronomy.com 13 2019 Looking ahead to next year ...

AFTER A DOWN over Indonesia and Malaysia. the darkest part of Earth’s shadow (Above) The Sun’s corona will blossom YEAR for solar eclipses in On the center line there, annu­ for 62 minutes. into view for those in 2018, the pace will pick up nicely larity will last up to 3 minutes, Besides the Mercury transit, the path of totality in 2019. The Moon will pass 40 seconds. several other planets will put on during the July 2, directly between the Sun and Earth The Moon isn’t the only object good shows in 2019. Venus will be 2019, solar eclipse. DAMIAN PEACH twice this year. The top event will to pass in front of the Sun in 2019. a brilliant object in the east before arrive July 2, when the Moon will On November 11, Mercury will dawn early in the year. Giant (Below) American completely cover our star’s disk transit the Sun’s face for the first Jupiter will reach opposition in observers will see along a narrow track that runs time in 3.5 years. Observers will June and ringed Saturn will follow the Moon totally immersed in Earth’s across the Pacific Ocean before see the planet’s black disk slowly a month later. Unfortunately, it umbral shadow making landfall in Chile and then traverse our star. People across will be a down year for Mars, January 20/21, 2019. moving into Argentina. North America can see at least though the Red Planet RICHARD McCOY Those seeking a land-based some of this event (wearing proper will recover adventure likely will head to Chile. eye protection, of course), with nicely in The path of totality will reach the those in the eastern third getting 2020. coast in the beautiful port city of the best views. La Serena, where totality will last Observers of lunar eclipses 2 minutes, 15 seconds. (The center won’t feel left out during 2019. line north of there will provide an Totality will wash over much of additional 21 seconds of totality.) Earth the night of January 20/21, But the prospects for good weather with viewers in North America improve as you head inland. If you having front-row seats to see the prefer a big-city environment, the spectacle. The Moon will traverse track will end at sunset in the sub- urbs south of Buenos Aires, where viewers can see up to 2 minutes of totality. The year’s second central eclipse will occur December 26. The Moon will appear smaller than the Sun, so observers will witness an annu- lar eclipse where a ring of fire will remain around our satellite. The eclipse track will cross parts of Mercury will transit the Sun on November 11, 2019, when the planet Saudi Arabia, Oman, and southern will appear as a black spot crossing the India before reaching maximum Sun’s disk. LEO AERTS

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