United States or Pakistan ? Vote for the TOP Country of the Week !
In every part of Europe, as well as in North America, observers devoted themselves to the daily study of the chromosphere and prominences. Foremost among these were Lockyer in England, Zöllner at Leipzig, Spörer at Anclam, Young at Hanover, New Hampshire, Secchi and Respighi at Rome. There were many others, but these names stood out conspicuously.
It is now shown that the effect is not produced, as formerly supposed, by the layers of the atmosphere lying just above the region which Professor Lockyer long ago named the chromosphere, but by the gases of higher regions. Reasoning from analogy, it may be supposed that a corresponding layer of the atmosphere of other stars is the one which gives us the reverse spectrum of those stars.
What we now call the "chromosphere" is an envelope of glowing gases, by which the sun is completely covered, and from which the "prominences" are emanations, eruptive or flame-like. Now, continual indications of the presence of this fire-ocean had been detected during eclipses in the eighteenth and nineteenth centuries.
Another peculiarity of the chromosphere, denoting the remoteness of its character from that of a true atmosphere, is the irregularity of its distribution over the sun's surface.
Lockyer in England, by which the monochromatic bands of the prominences are caused to obtain the mastery, and to appear in broad daylight. By searching carefully and skilfully round the sun's rim, Mr. Lockyer has proved these prominences to be mere local juttings from a fiery envelope which entirely clasps the sun, and which he has called the Chromosphere.
The faculties which would enable us to obtain a deeper and truer view of all the manifestations of cosmic energy would at the same time reveal to us new forms of beauty, new possibilities of pleasure on every side: and to take a single instance the emotions to which the sight of Niagara now appeals might then be gratified by a contemplation of the fierce grandeur of some sun's chromosphere or the calmer glories of its corona. That satisfies, does it not?" she added, with a sigh.
At times of minimum it seems to accumulate and concentrate its activity at the poles; while maxima probably bring a more equable general distribution, with local depressions at the base of great prominences and above spots. A low-lying stratum of carbon-vapour was, in 1897, detected in the chromosphere by Professor Hale with a grating-spectroscope attached to the 40-inch Yerkes refractor.
The "chromosphere" was, for the most part, shallow and quiescent; its depth, above the spot zones, had sunk from about 6,000 to 2,000 miles; prominences were few and faint. Obviously, if a type of corona corresponding to a minimum of sun-spots existed, it should be seen then or never. It was seen; but while, in some respects, it agreed with anticipation, in others it completely set it at naught.
The eclipse-photographs of 1893 disclosed to Hartley's examination the presence there of gallium; and those taken by Evershed in 1898 were found by Jewell to be crowded with ultra-violet lines of the equally rare metal scandium. The general rule had been laid down by Sir Norman Lockyer that the metallic radiations from the chromosphere are those "enhanced" in the electric spark.
As to established facts, we learn from the spectroscopic researches that the continuous spectrum is derived from the photosphere or solar gaseous material compressed almost to liquid consistency; that the reversing layer surrounds it and gives rise to black lines in the spectrum; that the chromosphere surrounds this, is composed mainly of hydrogen, and is the cause of the red prominences in eclipses; and that the gaseous corona surrounds all of these, and extends to vast distances outside the sun's visible surface.
Word Of The Day