Our Astronomical Column

Abstract

Mars.—An interesting example of the somewhat unusual atmospheric conditions exhibited on Mars at this apparition is described by E. C. Slipher (Pub. Ast. Soc. Pacific, Aug. 1922). This was a large white equatorial spot situated at the south end of Mar-garitifer Sinus; it was about 800 miles long, 400 miles wide, and comparable with the polar caps in brilliancy, though slightly more yellowish. There was no trace of it on July 8; it was very brilliant on July 9; on July 10 it was larger but fainter, and crossed by two greyish streaks; on July 11 it had split into three separate portions, of which only one, to the right of Margaritifer Sinus, remained on July 12. On July 13 and 14 the region had resumed its normal appearance. Whitish patches are frequently seen near the limbs, but they generally disappear near the central meridian, indicating that they are morning or evening mists or hoar frosts. This great spot, on the other hand, persisted in full strength throughout the Martian day. The article is illustrated by drawings and photographs, the latter being on a small scale, but fully confirming the changes in the aspect of the spot, which was probably cloud or mist. Its appearance shows that conditions on the planet's surface are by no means so stagnant as some assert.