Actual Astronomy - Messier Objects for August

Hosted by Chris Beckett & Shane Ludtke, two amateur astronomers in Saskatchewan who enjoy teaching astronomy classes and showing the public views through their telescopes. [e-mail]

 

On Episode 547 of Actual Astronomy, hosts Chris and Shane guide listeners through observing an array of August Messier objects across the constellations Ophiuchus, Scorpius, and Sagittarius. The show details viewing techniques for globular and open clusters—highlighting targets like the egg-shaped globular M19, the historical Ptolemy's Cluster (M7), and the beginner-friendly M23. Additionally, they explore iconic Milky Way nebulae, including the active star-forming Lagoon Nebula (M8) and the nearby Trifid Nebula (M20) with its distinctive three-lobed dark dust lanes.

 

1. M10 & M12 (Globular Clusters in Ophiuchus)

- Binoculars: Sweeping through central Ophiuchus reveals these two bright globulars in the same binocular field. They appear as soft, distinct bluishgray spheres.

- Telescope: In an 8-inch telescope, M12 resolves well into individual stars across its core, while M10 appears somewhat more tightly packed, brighter toward the center, and slightly fuzzier at the edges.

- Compare the two side-by-side: Despite being located near each other in our sky, M12 has lost a significant portion of its lower-mass stars due to repeated passages through the Milky Way’s dense galactic disk.

 

2. M107 (Globular Cluster in Ophiuchus)

- Binoculars: A challenging target for binoculars; requires dark skies and averted vision to spot as a minute, faint smudge.

- Telescope: Small-to-medium telescopes reveal a delicate, somewhat un-concentrated patch of light with a loose core.

- M107 contains noticeable dark dust lanes or obscuring regions, which is relatively rare for a globular cluster, giving it a unique visual texture in medium-to-large scopes.

 

3. M9 (Globular Cluster in Ophiuchus)

- Binoculars: Similar in scale to M107, though slightly brighter and easier to catch in 10x50s on a clear night.

- Telescope: Small scopes show a bright, unresolved central nucleus surrounded by a faint, grainy halo.

- M9 is located remarkably close to the Galactic Centre—only about 5,500 light-years away from it. It lies near dark nebulae like Barnard 64, making the surrounding starfield visually compelling.

 

4. M19 & M62 (Globular Clusters in Ophiuchus)

- Binoculars: Separated by about 4 degrees, both fit easily into a standard binocular field of view south of M10/M12. They look like round, soft patches brightening toward their centers, with M19 appearing noticeably brighter.

- Telescope: Smaller telescopes show compact, fuzzy disks. Moderate magnification begins resolving outer stars on both.

- M19 is famous for being one of the most distinctly oblate (egg-shaped) globular clusters known, likely due to tidal forces from its proximity to the galactic core.

- M62 has an asymmetric core, heavily deformed by galactic tidal forces, and hosts a rich population of millisecond pulsars.

 

5. M6 (The Butterfly Cluster) & M7 (Ptolemy’s Cluster) Scorpius

- Naked Eye: Both are bright and obvious to the naked eye under dark skies near the "stinger" of Scorpius.

- Binoculars: Binoculars provide the absolute best view. Both clusters fit together in a wide 10x50 field. M7 is larger and brighter; M6 displays a striking butterfly-like star arrangement.

- M7 is one of the oldest recorded deep-sky objects, noted by Ptolemy in 130 AD.

- The orange giant star BM Scorpii, which sits on the wing of the "Butterfly" in M6 and adds a nice pop of stellar color contrast.

 

6. M8 (The Lagoon Nebula) Sagittarius

- Naked Eye: Appears as a distinct, hazy patch in the Milky Way band above Scorpius.

- Binoculars: Shows as a huge, glowing oval patch—larger than the full Moon—with several bright stars embedded within it.

- Telescope / Filters: A UHC or O-III filter enhances the dark dust lane ("the lagoon") bisecting the bright nebulosity.

- M8 is an active star-forming region containing Bok globules (collapsing clouds of protostellar gas) and the famous "Hourglass Nebula" region at its core.

 

7. M20 (The Trifid Nebula) Sagittarius

- Binoculars: Located just 1.4 degrees northwest of M8. Appears as a faint, ghostly glow surrounding a central triple/multiple star system.

- Telescope: Medium scopes under dark skies reveal the dark dust lanes splitting the bright emission portion into three distinct lobes.

- M20 is a rare "triple threat" nebula containing an emission nebula (red in photos), a reflection nebula (blue in photos), and a dark dust lane network (Barnard 85) that gives it its name.

 

8. M21 (Open Cluster) Sagittarius

- Binoculars: Situated right next to M20. Appears as a small, compact, bright knot of stars.

- Telescope: Low-power views easily resolve 20–30 stars packed tightly together.

- The "Trifid Trio": In wide-field eyepieces or binoculars, you can view M8, M20, and M21 all in a single field of view, offering one of the most spectacular Milky Way vistas available to visual observers.

 

9. M23 (Open Cluster) Sagittarius

- Telescope: Low magnification is key. Small telescopes easily resolve over 80–100 stars spread across a wide field in subtle arc-like patterns.

- M23 sits against a rich background Milky Way star field, making low-power wide-field views ideal. It is an excellent target for beginners practicing star-hopping in northern late-summer skies.

 

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