11

Consider how far the pleiades are above the ecliptic, and how far the moon travels in a day. From this you can work the angle at which the moon must travel relative to the ecliptic, in order to cross the eliptic within a day. You can then compare this with the actual inclination of the moon's orbit to the ecliptic, and that will tell you if an eclipse is ...


10

There are few things here I think might be worth to state: The tilt of Earth is of no importance here. As the comment says what is of importance how much the Moon orbit is inclined to the ecliptic. Now, one can say that if both Sun-orbit and Moon-orbit have the same inclination to Earth equator (namely 23.5 deg) it means the Moon and Sun orbits have no ...


8

The precession of the moon's orbital plane does not align it with the ecliptic plane. The angle between those two planes is approximately 5.14° (it varies by ~±0.15°, mostly due to perturbation by the Sun). Precession causes the orientation of the lunar plane to vary, but the angle between the two planes stays (almost) the same. It's very similar to the ...


7

They made star maps. They mapped the posiitons of stars on the imaginary celestial sphere - whch they thought was an actual physical hollow sphere surrounding the Earth at some distance. Because the earth rotates, and they thought that the Earth stood still, they believed that the imaginary celestial sphere rotated around the Earth. They saw that stars ...


7

Edit: Getting the exact value winds up being simple, but it was only later in the day that the answer occurred to me. All we need to do is ask for the altitude and azimuth of the Ecliptic’s south pole! The ecliptic itself will be highest above our horizon in exactly that direction, at an altitude that is exactly 90° above its pole. Thus the answer is given ...


6

The planets do not orbit in the same plane as the Earth, they are inclined by a few degrees. This means that as they orbit the sun, they are sometimes above the plane of the Earth's orbit and sometimes below. And it takes one orbital period to go the full cycle from above, to below and back to the start. The reason that they appear further from the ecliptic ...


4

The angle MSP is the inclination of Mars relative to the ecliptic plane. This is 1.851 degrees The angle MEP is the Ecliptic latitude of Mars from Earth. This angle can be greater than 1.851 degrees. M S-----------------E--------------P S is the sun E is the Earth, M is Mars and SP is the plane of the ecliptic in this cross-...


3

Even from Earth, the Sun passes through non-zodiac constellations (if you use IAU constellation boundaries) It spends more time in Ophiuchus than in Scorpio, for instance. From Mercury, the Sun path would deviate from the Ecliptic (which is indeed defined by the plane of the Earth's orbit). The Sun would still pass through Ophiuchus, and it would also pass ...


1

I think I have it now. Basically I was thinking the other way around: the mode of thinking was: "What longitude component will arise from 3 arc min in altitude?" Indeed, if, for example, Jupiter will be observed 3 arc min higher than it really is, it will contribute to the longitude component no more than 3 arc minutes. The 3 minutes angular ...


1

As mentioned by James K in this answer, the inclination of the ecliptic plane to the invariable plane of the Solar System varies by ~3°, over a very long time scale. The invariable plane itself is very stable relative to the International Celestial Reference Frame (ICRF). The ICRF creates a quasi-inertial frame of reference centered at the barycenter of the ...


1

Have a look at https://www.pveducation.org, specifically section 2.4 on Terrestrial Solar Radiation. It describes the equations required and has some online calculators and interactive plots. If you wish to calculate in your own code, I'd recommend the pysolar Python package: https://pysolar.readthedocs.io/en/latest/. It has methods for taking the latitude, ...


1

What I think you're trying to do is workable, but approximate. You first find the Sun's geographical position (GP), the point on the Earth where the Sun is in zenith at the time of the observation. You start by finding the Sun's GP latitude (its declination). It's approximately 23 degrees times the sine of ((days since the vernal equinox)times 360/365). Then ...


1

Only since February 2018 there is a Wikipedia Page about the Great Year which is indeed a good read, but I think the German wiki version has a more concise summary, here an (approximate) translation with my highlighting: A great year or platonic year is the time during which the vernal equinox moves once through the zodiac. The designation of this cycle of ...


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