We have now subdued a parallactic light by causing it to shine through small apertures, but we have not taken from it its parallactic character; so that it can produce double shadows of bodies, although with diminished power.
For ourselves, we maintain that these again areparallactic double shadows, which appear edged with coloured borders and halos.
If A and B represent the positions of the spectators, M the moon, and C D an arc of the sky, then it is evident, that C D would be the parallactic arc.
The arc M N is called the parallactic arc, and the angle A C B, the parallactic angle.
The assured general fact as regards the direction of stellar movements was that they included a common parallactic element due to the sun's translation.
In the course of a year it is found that the difference in declination undergoes a periodic change, and from that change the parallactic ellipse can be computed.
If looked at edgeways it will be linear, if tilted a little it would be elliptic; but the ellipse would, even at that distance, be greater than the greatest parallactic ellipse of any star in the sky.
How shall we adequately describe the extreme minuteness of the parallactic ellipses in the case of even the nearest stars?
In the technical language of astronomers, we speak of this as the parallactic ellipse, and it is by measuring the major axis of this ellipse that we determine the distance of the star from the sun.
At a certain date, which can be readily computed, the star is at one end of the parallactic ellipse, and six months later the star is at the other end.
It will not, however, be necessary to take this into account, as the displacement thus arising in the lapse of a single year is far too minute to produce any inconvenient effect on the parallactic ellipse.
In a somewhat more popular manner, we would say that one thousand times the major axis of the very largest parallacticellipse would not be as great as the diameter of the full moon.
There is, however, a still graver and quite insuperable distinction between the parallactic path and the aberrational path.
We cannot, however, fail to notice that the parallactic ellipse belonging to B is much smaller than that of A.
This is partly due to its own motion, but it is also largely due to the parallactic displacement arising from the rotation of the earth, which may amount to so much as twenty seconds.
Brünnow sought to determine the parallactic ellipse by measuring the difference in declination between 61 Cygni and the comparison star.
Like nearly all its congeners, the star is situated in the full stream of the Milky Way, and we learn without surprise that micrometrical measures by Burnham and Barnard[1499] failed to elicit from it any sign of parallactic shifting.
The parallactic shift of the nearest of the stars as seen from opposite sides of the earth's orbit, is many times smaller.
The apparent motion of the stars due to this motion of the solar system is now called their parallactic motion, to distinguish it from the actual motion of the star itself.
The most obvious and direct method is to determine the parallacticmotion of the stars of known parallax.
Since every star has, presumably, a proper motion of its own, we can draw no conclusion from the apparent motion of any one star, owing to the impossibility of distinguishing its actual from its parallactic motion.
The periodic parallactic proper motion is caused by the motion of the earth around the sun, and gives the annual parallax (π).
From the parallacticmotion of the star it is possible to deduce its distance from the sun, or its parallax.
One of the pressing wants of astronomy at the present time is a parallactic survey of the heavens for the purpose of discovering all the stars whose parallax exceeds some definable limit, say 0"1.
Three of the twelve impressions were made at the epoch of maximum parallactic displacement, six at the minimum six months later, and three at the following maximum.
Ptolemy's parallactic rules, covered with brass, four cubits in the side.
Brass parallactic rules, which revolved in azimuth above a brass horizon, twelve feet in diameter.
If we ascertain the parallactic motion of a group of stars, then we can find their average distance.
By parallactic motion is meant the apparent displacement in consequence of the solar motion which is now known with great accuracy, and amounts to 19.
In researches upon the distribution of the more distant stars, the method of measuring parallaxes of individual stars fails completely, and the secular parallax, or parallactic motion of the stars is employed instead.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "parallactic" in a variety of sentences. We hope that you will now be able to make sentences using this word.
