I am glad to be able to report that observing conditions generally have been very good with us since the beginning of last month, and that at least one other member besides myself has taken advantage of the good seeing to make drawings of Jupiter. I am unfortunately divorced from my observatory for some months, but have with me in the country an excellent 5-in. Cooke altazimuth as well as accurate time.
I have never hitherto prosecuted a careful and continuous
study of the giant planet's surface, and confess to great surprise at the vast
and rapid changes that become apparent. This especially struck me first in the
case of the N. equatorial belt, the northern and equatorial components of which
exhibited alternately dark masses and condensations, divided by white spots
after intervals of only five Jovian rotations. On March 13 and 14 there were
typical instances of this.
On March 26, 20h 40m, G.M.T., a faint wisp across the
equator, was conspicuous, and next night, March 28, 2h 20m G.M.T., was
invisible, while the equatorial region near the c.m. showed considerable
change. Definition excellent, 4 to 5 on both occasions, power 200. The N.
temperate area, however, has puzzled me most, for the three belts often seen
have varied much both in visibility and latitude, while with exquisite
definition on April 1, at 0h 20m G.M.T., the following portion seemed overlaid
with vapour of a sage green tint, and the belts (2) were only faintly visible
in their preceding parts,
The Red Spot has been well seen on several occasions of
almond shape, the f. end slightly more pointed than the p. Its tint seemed
uniform, and a very delicate brick red, like a faint stain. It is overlaid on
the S. side by the S. temperate belt, which is closely double through nearly
its whole extent, and f. from the centre of the Red Spot is much darkened and
sinuous. The great spot's preceding end was estimated on c.m. at 1h 15m G.M.T.,
April 1, and the following end on c.m. at 21h 52m 36s G.M.T. of same date. In
the transit of Satellite I. on February 22, observed at Waverley, near Sydney,
with my equatorial, the shadow must have been occulted by the satellite, which
is perhaps worthy of note.
WALTE R F. GALE .
www.theramblingastronomer.co.uk
No comments:
Post a Comment