Hokuto Shichi Sei: Difference between revisions

Within Ursa Major the stars of the Big Dipper have [[Bayer designation]]s in consecutive [[Greek alphabet]]ical order from the bowl to the handle.

[[Image:BigdipISS.jpg|thumb|200px|right|<center>The Big Dipper's bowl and part of the handle photographed from the [[International Space Station]].<br>[[Zeta Ursae Majoris|Mizar and Alcor]] are at the upper right.</center>]]

| [[Alpha Ursae Majoris|&nbsp;&nbsp;Dubhe]] || &nbsp;&nbsp;&nbsp;&nbsp;α UMa || &nbsp; &nbsp; &nbsp; 1.8 || &nbsp; &nbsp;124

| [[Beta Ursae Majoris|&nbsp;&nbsp;Merak]] ||&nbsp;&nbsp;&nbsp;&nbsp;β UMa || &nbsp; &nbsp; &nbsp; 2.4 || &nbsp; &nbsp; &nbsp;79

| [[Gamma Ursae Majoris|&nbsp;&nbsp;Phecda]] || &nbsp;&nbsp;&nbsp;&nbsp;γ UMa || &nbsp; &nbsp; &nbsp; 2.4 || &nbsp; &nbsp; &nbsp;84

| [[Delta Ursae Majoris|&nbsp;&nbsp;Megrez]] || &nbsp;&nbsp;&nbsp;&nbsp;δ UMa || &nbsp; &nbsp; &nbsp; 3.3 || &nbsp; &nbsp; &nbsp;81

| [[Epsilon Ursae Majoris|&nbsp;&nbsp;Alioth]] || &nbsp;&nbsp;&nbsp;&nbsp;ε UMa || &nbsp; &nbsp; &nbsp; 1.8 || &nbsp; &nbsp; &nbsp;81

| [[Zeta Ursae Majoris|&nbsp;&nbsp;Mizar]] || &nbsp;&nbsp;&nbsp;&nbsp;ζ UMa || &nbsp; &nbsp; &nbsp; 2.1 || &nbsp; &nbsp; &nbsp;78

| [[Eta Ursae Majoris|&nbsp;&nbsp;Alkaid]] || &nbsp;&nbsp;&nbsp;&nbsp;η UMa || &nbsp; &nbsp; &nbsp; 1.9 || &nbsp; &nbsp; 101

In the same line of sight as [[wikipedia:Mizar (star)|Mizar]], but three light-years beyond it, is the star [[wikipedia:Zeta Ursae Majoris|Alcor]] (80 UMa). Together they are known as the [[Horse and Rider]].  At fourth magnitude, Alcor would normally be relatively easy to see with the unaided eye, but its proximity to Mizar renders it more difficult to resolve, and it has served as a traditional test of sight. Mizar itself has four components and thus enjoys the distinction of being part of an [[optical binary]] as well as being the first-discovered [[telescope|telescopic]] [[binary star|binary]] (1617) and the first-discovered  [[spectroscopic binary]] (1889).

Five of the stars of the Big Dipper are at the core of the [[Ursa Major Moving Group]]. The two at the ends, Dubhe and Alkaid, are not part of the swarm, and are moving in the opposite direction. Relative to the central five, they are moving down and to the right in the map. This will slowly change the Dipper's shape, with the bowl opening up and the handle becoming more bent. In 50,000 years the Dipper will no longer exist as we know it, but be re-formed into a new Dipper facing the opposite way. The stars Alkaid to Phecda will then constitute the bowl, while Phecda, Merak, and Dubhe will be the handle.