PLANETS IN MAY

Press, Volume C, Issue 29501, 1 May 1961, Page 7

PLANETS IN MAY

(By C. S. L. KEAY, Physict Dent. Umverstty of Gmt*.) The early morning sky this month will be traced by the appearance of the planet Ven® in all its splendour. No bright stars will be nearby to detract from its i brilliance. In fact when it reaches its greatest brilliance by the middle of May it will be bright enough to cast faint shadows, provided no other lights are present. Look for it in the northeast an hour or so before sunrise. At the same time another bright planet is visible high in the northern sky. It is Jupiter, the planet next in ortlllance to Venus. A little to the west of Jupiter lies =a turn, very much inferior in brilliance to Jupiter but Mill brighter than the surrounding stars. Jupiter and Saturn are now rising in time to be visible low in the east in the late evening. In. the early-evening sky this month the remaining two visible planets may be seen, lyow in the north* just after 'sunset appears the red plan® Mars, while Mercurv may perhaps be glimpsed * ow i n north-west The Word perhaps is necessary because this will not be a favourable month for sseujg the elusive planet Mertury. It will be helpful to refer to the times given below whenever the planets are. being observed, the times applying on May 2, 16, and 30 respectively: Mercury sets 5.28 pun., 5.51 p.m., 6.19 p.m.; Mara sets, 10.21 p.m, 10.4 p.m, 9.a0 pun.; Jupiter rises, 11.7 p.m, 10.15 pun, 9121 p.m.: Saturn rises, 1034 p.m.; 9.39 p.m.; 8.43 pun.; Venus rises, 5.4 am, 4.20 a m, 4.6 a.m. Radar Studies of Venus The Americans will soon conclude a two-month experiment using radar to unveil soma of the mysteries of Venus. Started in March, the experiment has been taking advantage of the close approach of Venus to the earth, which occurs every 19 months. Even so. the round trip for the radio signals is almost 60m miles, and takes about five minutes. To receive radio echoes from Venus is far from simple, and the latest advances in radio technique have proved essential. The experiment has several objectives, the most important being the accurate measurement of the astronomical unit of distance. The exact length of this unit, which is equal to the mean distance from the earth to the sun, has not yet been defined to within 10,000 miles. Needless to say, it is of vital importance in assessing the exact size of our corner of the universe. Other results which it is hoped the experiment will provide include the solution of the puzzle concerning the length of the day on Venus—in other words, the time v enus takes to spin on its axis. This has long been g mystery because of, more than anything else, the clouds Which perpetually s.ircud Venus Careful measurements of the strength of the received radar pulse will determine the reflectivity of the surface of Venus and therefore give some clues as to the nature of the surface.