What's Happened to Martian Atmosphere? Page 2

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From a comparison of photographs of terrestrial landscape made in blue light through different air-paths, Dr. Slipher concludes that the opacity of the Martian atmosphere to blue light is far greater than that of our own and that it is probably surrounded by a very considerable atmosphere; one that may contain a great amount of finely divided matter that scatters and absorbs to a great extent the short wave-lengths of light (the blue and violet rays), or it may be that its atmosphere contains some unrecognized constituent which peculiarly modifies the incident light.

One wonders if the great meteorological change over a great portion of the Martian surface indicated by the observations made at the Lowell Observatory in May may not be connected with the great sunspot activity that has taken place this year. That there is a connection between the cycle of sunspot activity and certain atmospheric phenomena observable on the planets Mars, Jupiter, and Saturn has been suggested frequently. Is this possibly an instance of the effect of increased solar activity, of which the increase in the number and size of sunspots is one manifestation, upon the atmospheres of the planets? We have ample proof that sunspots have an effect on the earth's atmosphere, producing magnetic storms, auroral displays, and an excess of ultra-violet rays, The atmospheres of the other planets probably would not be immune to the effects of these changes in solar activity even though the composition of their atmospheres is different from that of the earth.

Jupiter's Great Red Spot undergoes great fluctuations and changes in color. The intensity and color of the many spots on the giant planet's surface are constantly undergoing changes, and there is reason to believe that many of these changes in the brightness and color of disturbed areas in the planet's atmosphere are affected by sunspots and the radiations that emanate from them. Similar changes in the atmosphere of Saturn have been noted, particularly in the color and brightness of certain areas. It may be worth while for those who have telescopes and are interested in observing the planets Jupiter and Saturn to keep an eye open for any atmospheric phenomena of an unusual nature that may occur, such as the appearance of remarkably bright or dark areas or changes in color or intensity of spots or belts.

Mars, Jupiter, and Saturn are all in the evening sky this month, Mars is in quadrature on September 10 and will be found due south on that date, in Ophiuchus, a few degrees east of Antares. It is now of zero magnitude, decidedly reddish in color, and slowly decreasing in brightness as its distance from the earth increases.

Jupiter is in Sagittarius, and though rather low in the southern sky in northern latitudes, it is well placed for observation in the evening.

Saturn is in Pisces and will be in opposition with the sun on September 25, when it will rise at sunset and remain visible all the night. It is yellowish in color and about equal to Altair in brightness at this time.

Venus and Mercury are both morning stars this month. This is the best time of the year to observe Mercury in the morning sky, at the time of greatest western elongation, which will occur on September 30. The planet should be easily observable for a week or so before and after that date. It will be about eighteen degrees above the southeastern horizon at sunrise. Venus is now slowly drawing in toward the sun and rises about three hours before it. During the month it passes from Cancer into Leo.

Autumn will begin on September 23 at 6:13 A.M., Eastern Time, when the sun will cross the equator going south carrying spring to lands below the equatorial line.

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