Event Date: May 31st
Time: 1:06(.34) PM
Brief
We are only about three weeks from the June solstice: the summer one for our hemisphere, and winter for the southern hemisphere. The Sun has gained several degrees of northern declination since starting this blog at the 0º mark back on March 19th. For the first month, it moved a little more than 11º; for the second month, slightly over 8º. So far for the start of this final month before the solstice, it has moved about 2º. It is now only about 1 1/2º from its maximum declination, and will reach that more and more slowly as it comes closer. During the final week, there is barely any difference at all. Look at the ecliptic and celestial equator positioning in relation to each other. The light-yellow line left (east) of the meridian is where the 6h/90º marks meet, for r.a. and ecliptic longitude respectively.
Time: 1:06(.34) PM
Brief
We are only about three weeks from the June solstice: the summer one for our hemisphere, and winter for the southern hemisphere. The Sun has gained several degrees of northern declination since starting this blog at the 0º mark back on March 19th. For the first month, it moved a little more than 11º; for the second month, slightly over 8º. So far for the start of this final month before the solstice, it has moved about 2º. It is now only about 1 1/2º from its maximum declination, and will reach that more and more slowly as it comes closer. During the final week, there is barely any difference at all. Look at the ecliptic and celestial equator positioning in relation to each other. The light-yellow line left (east) of the meridian is where the 6h/90º marks meet, for r.a. and ecliptic longitude respectively.
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Looking to the far left, where the labels for the ecliptic and celestial equator are shown for clarity, we see that they are nearly parallel at this point. Using the celestial grid lines also, the ecliptic angles up (north) of the 10º one, labeled on the right side of the frame. It was at that marker where the Sun was in mid-late April, depending the exact date we are talking about. When the Sun reaches the solstice indicator, where the two grids align, it will be as far north in value as our Earth's axis tilt.
If we think ahead, this three-month northward movement of the Sun in declination will reverse: between the solstice and September equinox. By then, the Sun will retreat to the celestial equator. The three months after that, the declination numerical value rate increases the way it does during the spring, with the exception of the Sun heading south instead of north, on the dome. Finally, between the December solstice and March equinox, the numerical value changes the way it does between the June solstice and September equinox, by decreasing as the Sun moves back to the celestial equator northward. When that finally happens, if you remember my very first entry (accessed by the date-link in the brief), we reach the astronomical new year again!
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