صور الصفحة
PDF
النشر الإلكتروني
[graphic]
[ocr errors][ocr errors][subsumed][ocr errors][ocr errors][ocr errors][ocr errors][ocr errors][merged small][ocr errors][ocr errors][ocr errors][ocr errors][ocr errors][ocr errors][ocr errors][ocr errors][merged small][ocr errors][ocr errors][merged small][merged small]
[graphic][merged small]
[blocks in formation]

The Envelope. The envelope is that part of the comet which surrounds the nucleus only on that side which is next to the sun and opposite to the tail; in some instances it is united with the nucleus,-in general, however, it is situated at a greater or less distance from it; the envelope passes in two streams of light on opposite sides of the nucleus, and forms that singular and well known phenomenon called the tail. The matter which composes the envelope seems to consist of the matter of the nucleus itself, raised by the solar action; the envelope does not appear till the comet is near the sun, when it gradually rises from the nucleus, and sinks again as the comet retreats from the sun; in some comets several of these nebulous envelopes have been observed, arranged in strata, the interior being the brightest, and the exterior less brilliant and more diffuse.

Hast thou ne'er seen the comet's flaming flight?
The illustrious stranger passing, terror sheds

On gazing nations from his fiery train

Of length enormous; takes his ample round

Through depths of ether; coasts unnumbered worlds
Of more than solar glory; doubles wide

Heaven's mighty cape; and then revisits earth,

From the long travel of a thousand years.

« السابقةمتابعة »