by Shaphan Shank | Apr 3, 2023 | 0 comments

Leo Trio, NGC 3628, M65, M66
Leo Triplet. Clockwise from left: NGC 3628, M65, M66. Photo © Shaphan Shank.

Leo, the Lion, is high in the evening sky during April. Leo lies about 40° south of the Big Dipper, which puts it high in the southern sky near zenith for mid-northern latitudes. Leo is one of the easiest constellations to locate due to its relatively bright stars and distinctive shape. The head, neck, and front of Leo are marked by the “Sickle,” a chain of stars shaped like a sickle or backwards question mark. Leo’s body is a roughly rectangular outline of stars, with the bright star Denebola marking the Lion’s tail.

Since it is located well away from the band of the Milky Way, most of the telescopic targets in Leo are galaxies. However, there is one outstanding double star in this constellation. Algieba, the star at the base of the Lion’s neck, is a close double consisting of two golden stars separated by just under 5 arcseconds. You will likely need moderate magnification (80× or more) to cleanly split Algieba.

NGC 2903 is one of the brightest galaxies in Leo. To find this galaxy, start at Algenubi, the star at the curved end of the Sickle. From Algenubi, go about 3° west to a fainter star named Alterf. NGC 2903 is 1.5° south of Alterf. This spiral galaxy is tilted at an angle to us, so it appears about twice as long as it is wide. The spiral arms are prominent in photographs, but they are quite difficult to visually observe.

Most of the other bright galaxies in Leo are clustered in two small groups just south of the Lion’s body. The first of these galaxy groups lies about 2° south of the imaginary line connecting Regulus and Chertan, just over halfway from Regulus to Chertan. This group consists of five galaxies—M95, M96, M105, NGC 3384, and NGC 3389. The three Messier galaxies (those with an “M” preceding the number) are the brightest of the group. These three galaxies lie too far apart to fit into the same field-of-view, but you may be able to fit two of the three into the same field-of-view at low magnification. NGC 3384 and NGC 3389 lie next to M105 (the northeastern galaxy of the Messier trio). These three galaxies easily fit into the same field-of-view, even at high magnification. NGC 3384 is nearly as bright as M105, but NGC 3389 is significantly fainter.

The second bright galaxy group in Leo is even more impressive than the first. This triangle of galaxies, known as the Leo Triplet, lies about 2.5° southwest of the star Chertan. Two of the galaxies, M65 and M66, are slightly elongated spiral galaxies that look quite similar. The third galaxy, NGC 3628, is somewhat fainter than the first two. However, NGC 3628 is the most interesting galaxy of the three because it is a highly elongated, edge-on spiral that is bisected by a dark lane of dust. All three members of the Leo Triplet fit into the same field-of-view at low magnification, but don’t forget to use higher magnification to study the individual galaxies, especially NGC 3628.

Leo’s galaxies, like most other galaxies, are rather faint compared to many other telescopic targets. A dark sky and a large-aperture telescope make it much easier and more enjoyable to find and observe dim objects such as these. Persistence and observing experience are also important. If you fail to get a good view of Leo’s galaxies on your first try, come back to them another night. Even if two nights both appear to be clear, one night may be much more hazy and turbulent than the other. These atmospheric conditions can significantly impact the appearance of galaxies.

Star map of Leo

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