1. Ref: Wikipedia

2.  cataloged by Messier in 1771  including brightest  Nebulae ( 星雲 )  diffuse nebula  dark nebula ( 黑暗星雲 )  planetary nebula ( 行星狀 星雲 )  Star clusters  open cluster ( 疏散星團 )  globular cluster ( 球狀星團 )  Galaxies ( 星系 )

3.  contains 7,840 “deep sky objects”  compiled in the 1880s by J. L. E. Dreyer using observations mostly from William Herschel and his son JohnJ. L. E. DreyerWilliam HerschelJohn  later expanded with two Index Catalogues (IC I in 1896 & IC II in 1905), adding a further 5,386 objects from photographyIndex Catalogues

4.  Massive star-forming region

6.  Star cluster – Open Cluster

7.  Two open clusters

9.  elevation ~30 deg at 9pm toward the East direction tonight (2010/03/11)

11. Mizar and Alcor

12.  A “Grand design” spiral galaxy A pinwheel