M73 is an odd entry within the comet-hunter’s checklist: a small group of 4 stars forming a triangular form within the sky.
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August 24: Iapetus at eastern elongation
Charles Messier’s well-known checklist of non-cometary objects largely accommodates star clusters, nebulae, and galaxies — faint fuzzies it may very well be simple to confuse for a cometary nucleus in a telescope of the sort the comet-hunter was utilizing. However M73 is a little bit of an outlier, and also you’ll see why whenever you catch it in your sights tonight. A small scope is ideal for the job.
Situated in Aquarius the Water-bearer, M73 is already above the horizon by sundown and in nice viewing situation as quickly because the sky will get darkish. About 30° excessive within the southeast shortly earlier than 10 P.M. native daylight time, you’ll find it slightly below 3° southwest of magnitude 4.5 Nu (ν) Aquarii.
Though the intense Moon is close by in Capricornus, you don’t have to fret about it obscuring this explicit Messier object. That’s as a result of M73 is a small group of simply 4 stars, with three within the form of an equilateral triangle and the fourth simply to the northwest. Even with the intense background of moonlight, they need to present up in your scope.
Astronomers don’t imagine this grouping is bodily certain; as a substitute, these suns simply occur to fall shut collectively as we glance out into 3D house and see a 2D view of the sky. They’re apparently solely on Messier’s checklist as a result of, in keeping with the SEDS Messier Index, he charted its location concurrently M72 — a real globular cluster of stars simply 1.3° west of M73. This spherical conglomeration of previous stars is unquestionably simpler to confuse for a comet, and rather more indicative of the typical Messier object. However it’s going to even be troublesome to see with the Moon close by, so wait a number of days after which come again to this area to test it out.
Dawn: 6:21 A.M.
Sundown: 7:42 P.M.
Moonrise: 6:38 P.M.
Moonset: 3:32 A.M.
Moon Section: Waxing gibbous (96%)
*Occasions for dawn, sundown, moonrise, and moonset are given in native time from 40° N 90° W. The Moon’s illumination is given at 10 P.M. native time from the identical location.
Alison Klesman is senior editor of Astronomy journal. She holds a Ph.D. in astronomy and has studied a wide range of subjects, from minor planets to supermassive black holes.
