ASTRONOMY. 
to us, or more remote, but to the degree of 
obliquity with which its rays strike any part 
of the earth. 
The Moon is, next to the sun, the most 
remarkable of the celestial objects. Its form 
is spherical like that of the earth round 
which it revolves, and by which it is carried 
round the sun. Its orbit is also elliptical, 
having the earth in one of the foci of the 
ellipsis. The moon always keeps the same 
side towards the earth, shewing only at one 
time a little more of one side, and at another 
time a little more of the other side. When 
the moon is viewed through a good teles- 
cope, its surface appears covered with 
ridges, mountains, pits, and cavities of great 
variety. Some parts ot its surface also 
reflect less light than the rest. , It has been 
conjectured that the part which reflects the 
least light is water, and the brightest part 
laud. The heights of the lunar mountains 
were formerly supposed to be much greater 
than those of our earth ; but Dr. Herschel 
lias demonstrated that very few are more 
than half a mile high,' and the highest little 
more than a mile. Several volcanos, or 
burning mountains, have been discovered in 
it. It has been doubted whether the moon 
has an atmosphere like ours, but the latest 
observations appear to prove that it has. 
The moon is seen by means of the light 
which comes to it from the sun being re- 
flected from it. Its changes or phases de- 
pend upon its situation relatively to the 
earth and the sun. When the moon is in 
opposition to the sun, the enlightened side 
is turned towards the earth, and it ap- 
peal’s full ; when the moon is in conjunc- 
tion with the sun, its dark side is turned 
towards us, and it is invisible. As it 
proceeds in its orbit, a small part ot the 
enlightened side is seen, and then we have 
a new moon ; and we continue to see more 
and more of the enlightened side, as the 
moon approaches to the state of opposition, 
or full moon. The waning or decreasing 
of the moon takes place in the same man- 
ner, but in a contrary order. The earth 
must perform the same office to the moon 
that the moon does to us ; and it will ap- 
pear to the inhabitants of the moon (if there 
be any), like a very magnificent moon, 
being to them about 13 times as big as 
the moon to us, and it will also have the 
same changes or phases. The moon’s mo- 
tion is subject to many irregularities, on 
account of the inclination of its orbit to 
the plane of the ecliptic, and the attraction 
of the sun and the other planets. 
The moon has scarcely any difference of 
seasons; her axis being almost perpendi- 
cular to the ecliptic. What is very singu- 
lar, one half of her has no darkness at all ; 
the earth constantly affording it a strong 
light in the sun’s absence; while the other 
half lias a fortnight’s darkness and a fort- 
night’s light by turns. Our earth, as we 
have already observed, is undoubtedly a 
moon to the moon ; waxing and waning 
regularly, but affording her 13 times as 
much light as she does us. When she 
changes to us, the earth appears full to her ; 
and when she is in her first quarter to us, 
the earth is in its third quarter to her ; and 
vice versa. But from one half of the moon 
the earth is never seen at all : from the 
middle of the other half, it is always seen 
over head ; turning round almost 31) times 
as quick as the moon does. From the cir- 
cle which limits our view of the moon, only 
one half of the earth’s side next her is seen ; 
the other half being hid below the horizon 
of all places on that circle. To her, the 
earth seems to be the biggest body in 
the universe. As the earth turns round 
its axis, the several continents, seas, and 
islands, appear to the moon’s inhabitants 
like so many spots of different forms and 
brightness, moving over its surface; but 
much fainter at sometimes than others, as 
our clouds cover them or leave them. By 
these spots the Lunarians can determine the 
time of the earth’s diurnal motion, just as 
we do the motion of the sun : and perhaps 
they measure their time by the motion of 
the earth’s spots; for they cannot have 
a truer dial. The moon’s axis is so nearly 
perpendicular to the ecliptic, that the sun 
never removes sensibly from her equator ; 
and the obliquity of her orbit, which is next 
to nothing as seen from the sun, cannot 
cause the sun to decline sensibly from her 
equator. Yet her inhabitants are not des- 
titute of means for ascertaining the length 
of their year, though their method and ours 
must differ. For we can know the length 
of our year by the return of our equinoxes ; 
but the Lunarians, having always equal day 
and night, must have recourse to another 
method; and we may suppose, they mea- 
sure their year by observing when either 
of the poles of our earth begins to be en- 
lightened, and the other to disappear, which 
is always at our equinoxes , they being con- 
veniently situated for observing great tracts 
of land about our earth’s poles, which are 
entirely, unknown to us. Hence we may 
conclude, that the year is of the same ah- 
