Astronomical Occurrences In JANUARY 1829. Eternal Wisdom and eternal Love, Union ineffable, in bliss supreme, Extends around its intellectual beam. Whene'er the mental eye, with steady view, And ev'ry power expands with rapture new. Where the first motion wheels her mighty round, In self-enjoyment wrapt, and bliss profound. Marshals the seasons, and conducts the year: Not coldly distant nor oppressive near. In frost to slumber or to sink in fire, And stops awhile to tremble and admire. BOYD. Obliquity of the Ecliptic. This expression denotes the angle which the ecliptic makes with the equator, and which is subject to a small annual variation. The nature and magnitude of this in general has already been explained in our previous volumes: we shall, therefore, only insert in this place the measure of that obliquity for the usual epochs during the present year. January.. Ist, the true obliquity is 230 27' 33.1" ......... 23 27 33.6 ............. 23 27 32.7 October. Ist 23 27 33.4 December 31st ... 23 27 32.6 January.. Ist, the mean obliquity is 23 27 42:9 The equation of the Equinoctial Points at those respective times is January.. Ist + 3.8" 0:6 22 Ist ..... .... + 2.3 +0.7 SOLAR PHENOMENA. The Sun enters Aquarius at 44 m. past 5 in the morning of the 20th of this month; and he rises and sets, during every fifth day of the same period, as in the following Table. These times are computed for the meridian of the Royal Observatory, and a slight correction is therefore necessary for reducing them to any other place east or west of that meridian. This is done by converting the difference of longitude into time, at the rate of 15 degrees to an hour, and either adding the result to the above hour, or subtracting it from it, as the place is east or west of the first meridian. The time for any intermediate day may also be found by proportion, as already explained in our former volumes. 1 .... 59 3 57 51 7 .... 31 TABLE Of the Sun's Rising and Setting for every fifth Day. January 1st, Sun rises 5m, after 8, sets 55 m. after 3 6th 8 7 4 9 4 44 4 37 4 29 4 Equation of Time. The obliquity of the ecliptic and the unequal motion of the earth in its orbit create a difference between apparent and mean time,except on certain days in the year, when they both coincide. The former of these is that indicated by a good sun-dial; the latter by a well-regulated clock. The equation of time is an expression employed to denote the difference between them; and is to be employed when it is requisite to find the one from the other, which is done by either adding or subtracting the equation, as the case may require. The correction for any intermediate day must be found by proportion, according to the rule already given. Referring, therefore, to our former volumes for more particular information on the subject, particularly those for 1814, 1816, 1823, and 1824, we shall merely insert the value of the equation for noon of every fifth day. TABLE Thursday Jan. 1st, to the time by the dial add 3 57 11 43 12 56 m. 8. 6th...... 11th..... .16th...... 6 15 8 21 10 11 13 50 LUNAR PHENOMENA. Phases of the Moon. New Moon .... 5th day, at 52 m. after 3 in the afternoon First Quarter.. 12th........18. 7 in the morning Full Moon ....20th. .17 Last Quarter .. .28th, .21 5... 0... 10 ......... Moon's Passage over the Meridian. As the transit of the Moon affords the means of one of the simplest astronomical observations, we shall insert the times of a few of the most favourable for each month, for the sake of our young readers who may be disposed to exercise themselves in such pursuits. It may, therefore, be necessary to remind some of them, that the times specified are those answering to the first meridian of Great Britain; but these may readily be reduced to any other place, by means of the difference of longitude and the Moon's hourly motion. January 9th, at 36 m. after 3 in the afternoon 10th 29 Ilth 19 5 12th 6 13th 7 in the evening 14th 50 7 15th 40 8 9 5 6 30th 26 7 31st 21 8 PHENOMENA PLANETARUM. Phases of Venus. The phases of this beautiful planet are subject to change, like those of the Moon, which arises from her various positions and distances in reference to the Sun and the Earth. Like other astronomical pbenomena, they are susceptible of being correctly calculated, the method of doing which has already been explained in Time's Telescope for 1819. We shall, therefore, leave these computations for the exercise of such of our youthful readers as choose to perform them, and in sert the results for each month. Illuminated part = 9.90729 { 2.09271 January Ist Eclipses of Jupiter's Satellites. The most useful information on this subject having been inserted in our volume for 1818, we shall refer to it in preference to repeating it here, and merely state the times of such of these eclipses as will be visible at the Royal Observatory this month. As these are recorded in mean time answering to the first meridian, a slight correction in these respects will be requisite for other places, which may be easily made in the usual way. Immersions. Form of Saturn's Ring. The apparent form of this ring is subject to a slow change, the method of ascertaining which has been explained at page 52 of Time's Telescope for 1819. As this variation is only small, we shall merely insert the comparative magnitudes of the two axes for the first day of every third month. When the sign + is prefixed to the conjugate axis, it is the northern side of the ring that is visible; but when -- is employed, the south side of the ring only can be seen. 1.000 6th B .. Capricorn.. 6 in the morning Taurus Libra 9 in the morning Other Phenomena. Mercury will be in his superior conjunction at a quarter past 5 in the morning of the 14th; Saturn will be in opposition at 45 m. past 2 in the morning January 1st {Toansverse axis = 28 .. 1 We restrict the conjunctions in this place to stars of the first four magnitudes. |