TO KNOW THE STARRY HEAVENS 
53 
have been made to connect temperature 
changes with sunspots. The tempera- 
tures are slightly higher at sunspot 
minimum and it is now the time of 
sunspot minimum. As the period of the 
sunspots is nearly the same as the pe- 
riod of Jupiter’s revolution about the 
sun, attempts have been made to asso- 
ciate the two. Saturn also and other 
planets have been suspected of having 
an influence. The subject is still under 
investigation. 
None of the brighter planets are now 
visible in the early evening. Uranus is 
in Aquarius but not visible to the naked 
eye. Venus is brilliant as a morning 
fourteen minutes longer than the night. 
This lengthening of the day at the ex- 
pense of the night comes from the fact 
that the sun is counted as rising when 
its upper edge first appears above the 
horizon and considered as setting when 
its upper edge disappears. The refrac- 
tion due to earth’s atmosphere raises 
the sun a distance about equal to its 
diameter so that we see it rise about 
two and a half minutes sooner than we 
otherwise should and set later by the 
same amount. The fact that we use the 
edge of the sun instead of the center 
makes another minute difference in the 
times of rising and setting. In high lati- 
Figure 2. Chart showing times of sunrise and sunset, length of day and night, 
etc., for latitude forty degrees. 
star. On September 13 it makes a close 
approach to the planet Neptune. At 
seven o’clock in the morning of that 
day the two planets are closest, five 
minutes apart. As Neptune is always 
invisible to the naked eye a telescope is 
necessary to see this planet. 
jfj :fc S(C 5jc 
The Equinox. 
On September 23, 9:20 eastern stand- 
ard time, the sun crosses the equator 
going southward and autumn com- 
mences. This time is called the au- 
tumnal equinox because the day and 
night are of equal length. Strictly 
speaking, however, this is not true. On 
this day the sun rises at 5:49 A. M. 
and sets at 5 156 P. M. The day is thus 
tudes these differences are greater. It 
will be noted that the sun does not rise 
and set at six o’clock even disregarding 
these effects. This arises from the fact 
that our time is based upon the mean 
sun, which is at this time about eight 
minutes behind the real sun. Moreover 
the times of sunset and sunrise are al- 
ways expressed in the mean time of 
the observer, whereas we ordinarily 
use standard time, which is the mean 
time at the place adopted as standard. 
As this may differ a half hour or more 
from the mean time at the place of the 
observer, or even more than an hour 
and a half if daylight saving time is 
used, the almanac times may differ 
greatly from the time of the event by 
the watch. 
