Sun-spots Sentence Examples

Moestlin and his pupil Kepler - the latter applying it in 1607 to the observation of a transit of Mercury - also by Johann Fabricius, in 1611, for the first observations of sun-spots.

In 1611 Johann Fabricius published his observations of sun-spots and describes how he and his father fell back upon the old method of projecting the sun's image in a darkened room, finding that they could observe the spots just as well as with the telescope.

At first an apothecary, he turned his attention to astronomy, and in 1826 commenced his observations on sun-spots.

Among his happy conjectures may be mentioned that of the sun's axial rotation, postulated by him as the physical cause of the revolutions of the planets, and soon after confirmed by the discovery of sun-spots; the suggestion of a periodical variation in the obliquity of the ecliptic; and the explanation as a solar atmospheric effect of the radiance observed to surround the totally eclipsed sun.

The forms of these flocculi show that all sun-spots are vortical in nature, and are probably analogous to terrestrial cyclones or tornadoes.

The study of these vortices has led to the discovery of a magnetic field in sun-spots, apparently caused by electric convection in the vortices.

Photographs of the solar disk, taken with the H or K line, show extensive luminous clouds (flocculi) of calcium vapour, vastly greater in area than the sun-spots.

At most places the variation in the frequency has shown a general similarity to that of sun-spots.

This being inconvenient for comparison with sun-spots, use was made of his monthly values to obtain corresponding data for years commencing with January.

Taking the three years of greatest frequency at each maximum, and the three years of least frequency at each minimum, we get thirty years of many and thirty of few sun-spots.

The mean sun-spot frequency for the group of years of few sun-spots is almost exactly the same for the two subperiods, but the auroral frequency for the later group is nearly 40% in excess of that for the earlier, and even exceeds the auroral frequency in the years of many sun-spots in the earlier sub-period.

Wolfer's frequencies with data obtained by other observers for areas of sun-spots, and his figures show unquestionably that the unit in one or other set of data must have varied appreciably from time to time.

Greenland lies to the north of Fritz's curve of maximum auroral frequency, and the suggestion has been made that the zone of maximum frequency expands to the south as sun-spots increase, and contracts again as they diminish, the number of auroras at a given station increasing or diminishing as the zone of maximum frequency approaches to or recedes from it.

But his name is chiefly perpetuated through his investigation of the motions of sun-spots, by which he determined the elements of the sun's rotation and made the important discovery of a systematic drift of the photosphere, causing the rotation-periods of spots to lengthen with increase of solar latitude.

The last-named .volume contains Jevons's interesting speculations on the connexion between commercial crises and sun-spots.

These bands Julius calls dispersion bands, and then, assuming that a species of tubular structure prevails within a large part of the sun (such as the filaments of the corona suggest for that region), he applies the weakening of the light to explain, for instance, the broad dark H and K calcium lines, and the sun-spots, besides many remoter applications.

As regards sun-spots, however, Johann Fabricius of Osteel in Friesland can claim priority of publication, if not of actual detection.

Besides many papers communicated to the academy of sciences, of which he became a member in 1714, he published Memoires pour servir d l'histoire et au progres de l'astronomie (St Petersburg, 1738), in which he gave the first method for determining the heliocentric co-ordinates of sun-spots; Memoire sur les nouvelles decouvertes au nord de la mer du sud (Paris, 1752), &c.