My first Magazine Sky & Telescope - 04.2019

encounter with M81 a few hundred million years ago. The tidal effects trig- gered a tremendous burst of star forma- tion in M82, stars whose ﬁ erce stellar winds and supernova explosions are ﬂ inging gas and dust out of the galaxy. The slow dance of future encounters may ultimately merge the pair into a single galaxy in the remote future. Now that we’ve seen our pair, let’s go for three of a kind in the guise of the Leo Triplet, composed of Messier 65, Messier 66, and NGC 3628. The trio is pretty even at 23×, sitting 1° east of 73 Leonis. M65 and M66 appear bright, and NGC 3628 is nicely visible as an elongated streak. As shown in my sketch with a wide-angle eyepiece giving 102×, the galaxies are most fetching when sharing the ﬁ eld of view, but they surrender more detail when examined individually at 164×. M66’s core tips north-northwest, holding a bright elongated center. Delicate hints of spiral arms sprout from each end of the core, unwrapping counterclockwise in my mirror-reversed view. M65 bares a roundish core with a small brighter center. The brightest area of NGC 3628 stretches across 7′, while fainter tips that are best seen with averted vision extend the length to 11′. Gravitational interactions have left their mark on the Triplet. M66 boasts spiral arms that twist above the galaxy’s disk and an offset core. Even more mussed, NGC 3628 has oddly ﬂ ared ends as well as a tidal tail of gas and stars extending roughly a half million light-years. The tail’s tip is punctuated by Leo-TDG, thought to be a tidal dwarf galaxy formed from the tail’s debris. The Whirlpool Galaxy, NGC 5194, in Canes Venatici is one of the best targets in which to seek out spiral structure. As a bonus, its interacting companion NGC 5195 enhances the scene. Together they’re known as Messier 51. These galaxies are an easy catch at 23×, each one sporting a relatively large core. At 164× a bright nucleus dwells at the heart of each galaxy. NGC 5194’s arms can be traced fairly well, but not with the detail afforded by larger scopes. One of the arms reaches out toward its companion, yet remains beyond its grasp. Images seem to show the Whirlpool’s northern spiral arm latched onto its companion, but this is an illusion. NGC 5195 is tumbling by its larger neighbor, and we merely see the arm superimposed on the receding companion. The Whirlpool’s pronounced, two-armed spiral structure may have been induced by the gravita- tional effects of an earlier encounter. Way over on the opposite end of the Big Bear from M81 and M82, Messier 101 is an intriguing galaxy for a small telescope. At 23× its large, diaphanous glow brightens only slightly toward the center. On a good night, a magniﬁ ca- tion of 164× coaxes out three spiral arms. A 13th-magnitude star sits 1.3′ north-northeast of the small nucleus. At low magniﬁ cation the galaxy spans roughly ¼°, but the outer reaches seem to fade away at 164×, so my sketch on the next page only covers the central 9′ of the galaxy. On very good nights, better than the two I had for this sketch, I’ve been able to nab a few of the brightest star-forming regions in M101’s outlying arms, notably NGC 5471, NGC 5462, NGC 5461, and the combined glow of NGC 5447 and NGC 5450. In addition to favorable skies, it takes patience and the judicious use of averted vision to hunt these down. If you’d like to tackle the project, you’ll ﬁ nd a labeled chart to help you on S&T’s website ( skyandtelescope.com ). Just enter “Guide to Messier 101” in the search box. Let’s end our tour with NGC 5907 in Draco, a lovely example of a ﬂ at galaxy — a disk-shaped galaxy that’s seen edge-on from our vantage point on Earth and has little or no central bulge. I ﬁ nd these celestial toothpicks of light quite appealing. Although fairly faint, the slender glow of NGC 5907 can be seen tipped north-northwest at 37×. Examining it at 102×, I can follow its length for about 8′, shining faintly at the tips and growing softly brighter toward the center. Folks with 8-inch or larger scopes should look for this remarkable galaxy’s dust lane. Deep images of NGC 5907 are spec- tacular. Magniﬁ cent loops of stellar M81 W N M82 W N NGC 3628 M65 M66 W N p Top: Increase the magnifi cation to reveal more of M81’s structure. A brighter core is readily apparent, but the delicate spiral arms take more study. This sketch shows the au- thor’s view of M81 at 164×. All sketches shown here were made with a 130-mm refractor. Middle: At 164×, M82’s mottled appearance becomes more visible. Look for the dark dust lanes interrupting its brighter areas, particularly on the galaxy’s south edge. Bottom: Use a wide-angle eyepiece and lower magnifi cations (the scene here was captured at 102×) to keep the trio of M65, M66, and NGC 3628 in the same fi eld of view. sk yandtele scope.com • A PR I L 2 019 55

My first Magazine Sky & Telescope - 04.2019 | Page 57