The Birmingham age-herald., 1922-04-02
THE STARRY SKIES IN APRIL By PROFESSOR BARTON of University Pennsyvania

Ursa Major tthe big bear) now lies in it's best position nearly overhead. The constellation will be seen to con- slst of quite a few stars other. than the seven forming the familiar big dipper. by means of which the con stellation is usually Identified. There is a group of stars west of the gowl arranged roughly in the form of semi i-circle. ending in a pair of stars al A, at the southern end. Just south of. this pair, and nearly overhead. is the faint constellation Lynx. Farther east, at B. is another pair in Ursa Major. south of which lies the faint constellation Leo Minor. Sthl far ther east Is another pair in Ursa Major, at c. These three similar pairs mark three of the paws of the bear.
 The ancients recognized two kinds of stars, the fixed stars and the nov ing stars called by the Greeks plan ots. which in their language meant wanderers. To them It seemed that the fixed stars always remained In the same positions with respect to each other, or, in other words that a eonfiguration such as the big dipper would always remain a dipper of eN- actly the, same shape. Bruno about 500 seems to have been the first to question the correctness Of this view and to suggest that this might not be so Haley in 17fs was the first actually to prove that any of the so- called fixed stars move. Since then many have been found to- move. and astronomers feel sure that all arc moving. The motions of tho stars in the big dipper are particularly. inter esting In 1888 Proctor called atten- ton to the very peculiar fact that five of the seven stars forming the dip per moved slowly in parallel direc- tions at the samo rate. The other two moved in a direction nearly opposite, the motions of these two being quite similar. The facts indicated pretty conclusively that the five stars eon- stituted a system moving together through space under some common in- fluence. The stars are so far apart that no one would have suspected any relationship between them. The stars at the end of the handle and the northernmost star of the two on the farther side of the bowl do not be- long to the system.
 Figure shows what is occurring. The dots show the present positions of the seven stars a900). The ar, rows indicate the direction and amount of the stars motions in o0.Oo0 years. The lower figure shows the shape of what is now the big dipper after 50 900 years. the figure being that found by joining the points of the arrows in the upper figure. There Is then no longer a close resemb blanee to a dipper, but then by that time the shape of dlppers may also have undergone changes
 Other moving clusters have since been found until now there are about seven such groups known including the Hyades. and the Pleiades, none however. soem as remarkable as the Ursa Major group, " have not fin ished the story. "A still further as tonishing fact was pointed out by Hertzsprung ia 1909 when he an nounced that there were eight more stars moving In just the same direc- tion as the five of the big dipper and, therefore belonging to the system. Other stars have since been added. Bottlinger in 1914 including IT in the group with some others which may perhaps belong also. The star next to the end of the handle of the dip per (Mizarl is a double star and close beside it is the star Alcor. which belongs to tho system. as does faint star In the position marked D. nak- ing eight in all In Ursa Major The other nine are scattered at in Au- riga, at in Corona, at c in Serpens, faint ones at H in Bootes, at I in VirEo and at in. Eridanus on the western horizon, one in CyEnus not visible to the naked eye and not marked very close to the northern horizon and one In Cetus, below the southwestern horizon. Lastly, the most notable member of the system ls the brightest Of all the stars Si ring a K in Eaniz Ma t0r
 We thus find that all of these IT stars but one are above our horizon now. but scattered over the whole visible hemisphere Each of them is moving slowly away from. the point Lynx marked R. This shows that the stars are moving in parallel lines The motions appear to radiate from a point because of perspe pective for the same reason that meteors of