Ursa Major

by | Apr 7, 2022 | 0 comments

Galaxies in starry sky

Ursa Major, the Great Bear, is a large constellation in the northern circumpolar region of the sky. Ursa Major is known best for the Big Dipper, which makes up the northeastern part of the constellation. Although it can be seen all year from mid-northern latitudes, April is probably the best time to look at all this constellation has to offer.

M81 and M82 are a pair of bright galaxies in the northern part of Ursa Major. M81 is a face-on galaxy from Earth’s point of view, while M82 is edge-on to us. These two galaxies can be seen with binoculars as two dim little spots of light, but a telescope and dark skies are required to really see the pair for what it is. M81 is brighter than M82, but it doesn’t have a lot of observable detail. However, careful observation with a large telescope may reveal subtle spiral structure of this galaxy. M82 contains an interesting mix of bright areas and dark lanes. The two galaxies are a little over 0.5° apart, so they are visible in the same field of view at lower magnifications. NGC 3077 is another small galaxy that will be just just outside the field of view.

To find M81 and M82, draw an imaginary line from Phad through Dubhe, extending the line the same distance again beyond Dubhe. The galaxy pair will be about 1° northeast of the end of your line.

M97 and M108 make up an even more interesting pair of deep sky objects. M97, the Owl Nebula, is a planetary nebula, while M108 is a barred spiral galaxy situated nearly edge-on to us. M97 is almost perfectly round, with two small darker spots, or “eyes,” giving the nebula its name. These dark spots can be difficult to see with smaller scopes or under poor conditions. M108 doesn’t show a lot of detail, but you may be able to see a little mottling or dark structure in it. M108 is about 1.5° southeast of the star Merak; M97 is another 0.8° southeast. After finding and viewing the pair at low magnification, boost the magnification to study each object more closely.

Mizar, the star in the middle of the Big Dipper’s handle, is one of the most well-known and observed double stars in the sky. Mizar forms a naked-eye pair with another star called Alcor. However, point a telescope at Mizar, and you will see a much tighter pair of stars. Mizar’s two component stars are white and are separated by about 14 arcseconds. Low magnification will split Mizar nicely.

M101, the Pinwheel Galaxy, lies just a few degrees east of Mizar. It forms a nearly equilateral triangle with Mizar and Alkaid, the first star in the Big Dipper’s handle. M101 is a large face-on spiral galaxy, with an apparent diameter of almost 0.5°. Because its light is spread over such a large area, this galaxy has a fairly low surface brightness. It is relatively easy to observe under dark skies, but light pollution makes it much harder to see. M101 is visible with binoculars as a small round glow of dim light. With a mid-sized (8”+) telescope, the spiral arms should be evident with careful observation at moderate magnifications.

Constellation map

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