Springtime is galaxy season in Canada. From March to May, the Milky Way and its obscuring gas and dust hugs the horizon during much of the night, revealing a myriad of distant galaxies overhead.
Because Charles Messier and his contemporaries were searching for comets, it’s not surprising that their list of “nuisances” ended up containing 40 galaxies. While large nearby galaxies like Andromeda (Messier 31), Triangulum (Messier 33), and the Pinwheel Galaxy (Messier 101) show obvious structure in the telescopes used by Messier and today’s amateur astronomers, more distant galaxies look very much like comets.
In the eyepiece, a typical galaxy will exhibit a faint halo surrounding a brighter core. Depending on the galaxy type and its orientation, the halo you see will be round or oval-shaped, or elongated — just like a comet tail! Meanwhile, the galaxy’s core resembles the coma of an active comet. The galaxies that Messier discovered during his sweeps failed to move compared to the surrounding stars — telling him that they weren’t comets. It’s a shame he didn’t appreciate what those comet imposters truly were!
Modern backyard telescopes are capable of showing you hundreds of galaxies, if you know where to look — and observing them gets easier with practice.
Tips for finding and viewing galaxies
Most GoTo telescope databases contain thousands of galaxies, but you can find plenty of them without
aid by using the right combination of equipment and technique. Also, many observing programs require you to manually find the objects and then describe what you saw in a log book.
While faint, galaxies tend to be larger than you might expect, making them quite easy to find under dark, transparent skies. For best results, try to observe galaxies when they are higher in the sky — that’s where there’s less atmosphere to extinct, or dim, their light.
Telescopes with apertures of six or eight inches (152mm to 203mm) and higher, are best for viewing galaxies. The widely-available (and affordable) Dobsonian-mounted Newtonian reflectors deliver a wide field of view (or FOV) owing to their low focal ratio of about f/5.9, especially when used with your longest focal length eyepiece. A 40mm Plössl eyepiece in an eight-inch f/5.9 reflector will produce a 1.4-degree diameter field, while a more expensive Tele Vue Nagler 31mm eyepiece, with its 82-degree apparent field of view, will show more than 2 degrees of sky. Working with such a generous field of view avoids the need for a tracking mount.
Tip: Even if you are using a GoTo system, start your search with low magnification and then swap in a stronger eyepiece to see more details.
I highly recommend the Telrad or Rigel finders that overlay a non-magnified, red bulls-eye on the sky. I have successfully located dozens of galaxies just by positioning the bulls-eye in the general direction indicated on my sky atlas or app.
For dimmer galaxies, I find it helpful to have a detailed star chart and a circle template that matches the field of view I’m seeing. Then I match star patterns, and determine where the galaxy should sit compared to the stars around it. Don’t forget that your telescope’s optics can alter the angle of the galaxy’s halo (usually drawn as an oval on star maps). A Newtonian reflector rotates the view by 180 degrees, so just turn your sky chart upside-down to match the eyepiece view. Better apps like SkySafari 6 and SkyTools 4 will let you display an FOV circle and flip the display to match your telescope’s optics.
If at first you don’t see the galaxy, try gently tapping the telescope’s tube while looking into the eyepiece. The jiggling starfield can often reveal a faint, fuzzy patch you previously overlooked. Averted vision will also brighten galaxies. In any case, be patient, and observe long enough for moments of clear seeing to reveal your quarry. A comfortable observing chair will help.
Chris Vaughan is a science writer, geophysicist, astronomer, planetary scientist and an “outreach RASCal.” He writes Astronomy Skylights, and you can follow him on Twitter at @astrogeoguy. He can also bring his Digital Starlab portable inflatable planetarium to your school or other daytime or evening event. Contact him through AstroGeo.ca to tour the Universe together.
This is a portion of an article that was first published in the March/April 2021 issue of SkyNews.