Page:Polar Exploration - Bruce - 1911.djvu/16

12 3. Though there is only one time there are different seasons, because these depend on the position of the earth in its orbit and on the inclination of the polar axis to the plane of the ecliptic.

4. The apparent path of the sun is an ascending spiral from the vernal equinox till the summer solstice, and a descending spiral from the summer solstice till the autumnal equinox. Thus it is possible to take meridian altitude of the sun during the whole summer six months at the North Pole, at any moment, or at every moment, no matter where the sun is in the spiral. Exactly the same thing may be said of the moon when she is north of the Equator.

5. The greatest possible altitude of the sun above the horizon is about 23½ degrees (actually at Greenwich mean time, 1911, June 22nd, 2$h$ p.m., 23° 27′ 9″.8). It reaches this altitude only at that date.

6. The constellations never set at the North Pole, their apparent paths (neglecting their own very tiny movements) being in circles, round the Pole; like the sun, they are always south of the North Pole.

7. When standing at the North Pole it is impossible to look in any other direction along the earth's surface but south. To the left or to the right, behind or in front of the person