The Star Book: Stargazing throughout the seasons in the Northern Hemisphere

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Peter Grego. The Star Book: Stargazing throughout the seasons in the Northern Hemisphere

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THE STAR BOOK STARGAZING THROUGHOUT THE SEASONS IN THE NORTHERN HEMISPHERE

PETER GREGO

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The two front stars of the Plough, Alpha UMa (Dubhe) and Beta UMa (Merak) are known as the Pointers, since an imaginary line extending from them leads to Polaris and the north celestial pole. Zeta UMa (Mizar), the second star of the Plough’s handle, has a fainter magnitude 4 partner, 80 UMa (Alcor), which is visible with the unaided eye. Mizar itself is a close double star, with components of magnitudes 2.2 and 3.8, separable with a small telescope.

A pair of galaxies bright enough to be seen through binoculars, Bode’s Galaxy (M81) and the Cigar Galaxy (M82) lie in the far north. Just half a degree apart, the pair is visible in the same low-power telescopic field. While M82 is almost edge-on to us, M81 is tilted at less of an angle. Some ten million light years distant, these galaxies are interacting with each other. On the other side of the constellation, the face-on spiral galaxy M101 is visible through binoculars as a circular smudge, and appears mottled through a 200mm telescope.

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